[Merge] (DirectGLES, ShaderTranspiler): land GL43 wave4 with the interface-block rename inside the L2 boundary

fixed Asio include bug and added the ignored dir item .gradle

CMakeLists.txt

@@ -270,6 +270,7 @@ set(SOURCE_FILES
     MobileGL/MG_Util/ShaderTranspiler/ShaderCompiler.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpvcSession.cpp
     MobileGL/MG_Util/ShaderTranspiler/ShaderSourceProcessor.cpp
+    MobileGL/MG_Util/ShaderTranspiler/TranslationCache.cpp
     MobileGL/MG_Util/ShaderTranspiler/glslang/TMglGlslIoResolver.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/FlattenInterfaceStructPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/EliminateFloatEqualsZeroPass.cpp
@@ -279,8 +280,10 @@ set(SOURCE_FILES
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/DecoratePositionInvariantPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/DemoteFloat64Pass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/LowerDrawParametersPass.cpp
+    MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/LowerViewportIndexPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/PackDoubleVertexInputsPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/FlattenXfbInterfaceBlocksPass.cpp
+    MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/UniquifyIoBlockNamesPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/SplitArrayVertexInputsPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/RebaseInstanceIndexPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/ZeroBaseVertexPass.cpp
@@ -291,6 +294,7 @@ set(SOURCE_FILES
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/NormalizeRectCoordinatesPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/Lower1DArrayImagesPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/BakeImageFormatsPass.cpp
+    MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/ClampMultisampleFetchPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/PrivateToEntryLocalPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/StripUniformLocationsPass.cpp
     MobileGL/MG_Util/ShaderTranspiler/SpirvPasses/StripUboMemberRelaxedPrecisionPass.cpp
@@ -386,6 +390,7 @@ set(SOURCE_FILES
     MobileGL/MG_State/GLState/TextureState/TextureState.cpp
     MobileGL/MG_State/GLState/ProgramState/ProgramObject.cpp
     MobileGL/MG_State/GLState/ProgramState/ProgramLinkTask.cpp
+    MobileGL/MG_State/GLState/ProgramState/ProgramTranslationCache.cpp
     MobileGL/MG_State/GLState/ProgramState/ProgramSpirvTask.cpp
     MobileGL/MG_State/GLState/ProgramState/ShaderCompileTask.cpp
     MobileGL/MG_State/GLState/ProgramState/ShaderObject.cpp

MobileGL/Config.h

@@ -203,6 +203,15 @@ namespace MobileGL::MG_Config {
         // immediately stay serial by their own construction). Off by default; never
         // advertise it.
         QuirkOverride AsyncOptimisticShaderStatus = QuirkOverride::Auto;
+        // MOBILEGL_SHADER_CACHE: the three-level, in-memory shader translation memo
+        // (MG_Util/ShaderTranspiler/TranslationCache.h). The levels follow the GL
+        // entry points - L1c memoizes one glCompileShader's PARSE VERDICT, L1 a
+        // linked program's whole front end, L2 DirectGLES's emitted ESSL. Auto is
+        // ON; ForceOff turns ALL THREE off and makes every translation run from
+        // scratch. The escape hatch exists because a wrong cache hit is a silently
+        // miscompiled shader: if a device ever renders differently with the cache
+        // on, one run with this falsy says so.
+        QuirkOverride ShaderTranslationCache = QuirkOverride::Auto;
     };
     extern FeaturesTable Features;
 } // namespace MobileGL::MG_Config

MobileGL/ConfigLoader.cpp

@@ -194,6 +194,7 @@ namespace MobileGL::MG_ConfigLoader {
         features.AsyncShaderCompileThreads = QueryEnvUint32("MOBILEGL_ASYNC_SHADER_COMPILE_THREADS", 0, 0, 64);
         features.AsyncOptimisticShaderStatus =
             QueryEnvQuirkOverride("MOBILEGL_ASYNC_OPTIMISTIC_SHADER_STATUS");
+        features.ShaderTranslationCache = QueryEnvQuirkOverride("MOBILEGL_SHADER_CACHE");
     }
 
     inline void InitBackendType() {

MobileGL/Init.cpp

@@ -18,6 +18,8 @@
 #include <MG_Impl/GLImpl/Query/GL_Query.h>
 #include <MG_Util/Async/ShaderCompilePool.h>
 #include <MG_Util/ShaderTranspiler/ShaderCompiler.h>
+#include <MG_State/GLState/ProgramState/ProgramTranslationCache.h>
+#include <MG_Util/ShaderTranspiler/TranslationCache.h>
 
 #include <atomic>
 #include <mutex>
@@ -72,6 +74,14 @@ namespace MobileGL {
             // built-in symbol tables the prewarm latch stands for, so leaving it set would
             // make the next Initialize() skip a prewarm it genuinely needs.
             MG_Util::ShaderTranspiler::ShaderCompiler::ResetPrewarmLatch();
+            // The two-level translation memo. Nothing in it references a glslang object -
+            // both levels hold plain bytes - so this is RSS hygiene rather than a lifetime
+            // requirement, and it is safe either side of FinalizeProcess. Stats first: an
+            // fordebug build gets one line per level saying how the run went.
+            MG_Util::ShaderTranspiler::LogShaderTranslationCacheStats();
+            MG_Util::ShaderTranspiler::ClearShaderTranslationCaches();
+            MG_State::GLState::LogProgramTranslationCacheStats();
+            MG_State::GLState::ClearProgramTranslationCache();
             MG_Backend::gBackendFunctionsTable = {};
             g_isInitialized = false;
             if (logLifecycle) {

MobileGL/MG_Backend/BackendObject.h

@@ -14,6 +14,7 @@ namespace MobileGL {
     namespace MG_State::GLState {
         class FramebufferObject;
         class ITextureObject;
+        class RenderbufferObject;
     }
 
     enum class BackendType {
@@ -24,6 +25,19 @@ namespace MobileGL {
     };
 
     namespace MG_Backend {
+        // One endpoint of a glCopyImageSubData. GL 4.6 core 18.3.2 accepts GL_RENDERBUFFER
+        // alongside the ten whole-image texture targets, and a renderbuffer name lives in a
+        // namespace of its own - so an endpoint is a sum type, not an ITextureObject. At most
+        // one of the two pointers is set; neither is set when the name named nothing, which is
+        // the INVALID_VALUE the frontend validator reports.
+        struct CopyImageEndpoint {
+            SharedPtr<MG_State::GLState::ITextureObject> Texture;
+            SharedPtr<MG_State::GLState::RenderbufferObject> Renderbuffer;
+
+            Bool IsRenderbuffer() const { return Renderbuffer != nullptr; }
+            Bool Exists() const { return Texture != nullptr || Renderbuffer != nullptr; }
+        };
+
         enum class FormatCapability : Uint64 {
             Creatable = 1ull << 0,
 
@@ -160,9 +174,9 @@ namespace MobileGL {
                                    GLsizei height, GLint border);
             void (*CopyTexSubImage2D)(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y,
                                       GLsizei width, GLsizei height);
-            void (*CopyImageSubData)(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+            void (*CopyImageSubData)(const CopyImageEndpoint& src,
                                      GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                                     const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                                     const CopyImageEndpoint& dst,
                                      GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                                      GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth);
             void (*GenerateMipmap)(GLenum target);
@@ -236,6 +250,14 @@ namespace MobileGL {
             // (optional; null = frontend falls back to CPU accounting).
             BackendQueryHandle (*BeginXfbPrimitivesQuery)(Bool generated);
             void (*EndXfbPrimitivesQuery)(BackendQueryHandle query);
+            // Whether GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN should be answered from the
+            // frontend's own accounting wherever that accounting is exact - a capture with no
+            // geometry stage - instead of from the query above. Set by DirectGLES, whose result
+            // is whatever the ES driver's PRIMITIVES_WRITTEN counter says: Adreno reports twice
+            // the written count for a vertex-only capture that follows a large render pass,
+            // where the desktop-exact answer is the one the frontend already computed. Defaults
+            // to false, so a backend that never sets it keeps using its GPU result.
+            Bool PrefersCpuXfbPrimitiveAccounting = false;
             // Transform feedback capture spans, for backends whose own GL/ES driver
             // performs the capture (DirectGLES). Both optional; null means the backend
             // drives capture from its draw recording instead (DirectVulkan). End is
@@ -318,6 +340,22 @@ namespace MobileGL {
             Int MaxVertexAttribs = 16;
             Int MaxComputeShaderStorageBlocks = 8;
             Int MaxCombinedShaderStorageBlocks = 32;
+            // Per-stage GL_MAX_*_SHADER_STORAGE_BLOCKS. Zero is a legal answer for the four
+            // non-compute, non-fragment stages and these defaults are the spec minimums, not
+            // placeholders: GL 4.6 table 23.64 and ES 3.2 table 21.44 both set the minimum for
+            // vertex, tessellation control, tessellation evaluation and geometry at 0, and only
+            // fragment (8 in GL, 4 in ES) and compute are guaranteed to have any. Every real ARM
+            // GLES driver takes that allowance - a Mali-G925 reports 0 for all four - so a
+            // backend that cannot honour a graphics-stage storage block MUST report 0 here
+            // rather than a hopeful number. Advertising a non-zero count the driver will refuse
+            // does not make the block work; it only moves the failure from an honest
+            // "unsupported" at query time to a backend link error the frontend never surfaces,
+            // after which every draw with that program silently renders nothing.
+            Int MaxVertexShaderStorageBlocks = 0;
+            Int MaxTessControlShaderStorageBlocks = 0;
+            Int MaxTessEvaluationShaderStorageBlocks = 0;
+            Int MaxGeometryShaderStorageBlocks = 0;
+            Int MaxFragmentShaderStorageBlocks = 8;
             Int MaxComputeUniformBlocks = 12;
             Int MaxComputeWorkGroupInvocations = 128;
             Int MaxShaderStorageBufferBindings = 8;
@@ -334,8 +372,32 @@ namespace MobileGL {
             Int MaxComputeImageUniforms = 8;
             Int MaxDrawBuffers = 8;
             Int MaxColorAttachments = 8;
+            // GL_MAX_CLIP_DISTANCES. Zero is a legal answer here, not a placeholder, and a
+            // backend that cannot host a clip distance MUST report it: advertising eight the
+            // backend will refuse does not make gl_ClipDistance work, it only moves the failure
+            // from an honest "unsupported" at query time to a backend shader-compile error the
+            // frontend never surfaces, after which every draw with that program silently renders
+            // nothing. DirectGLES fills it from GL_EXT_clip_cull_distance, DirectVulkan from the
+            // shaderClipDistance device feature. The DEFAULT stays at the GL 4.3 core minimum
+            // because it describes the no-backend case (standalone shader compiles, unit tests),
+            // where there is no device to be honest about and BuildTBuiltInResource still has to
+            // hand glslang a workable gl_MaxClipDistances.
             Int MaxClipDistances = 8;
             Int MaxViewports = 16;
+            // GL_LAYER_PROVOKING_VERTEX / GL_VIEWPORT_INDEX_PROVOKING_VERTEX: which vertex of a
+            // primitive supplies gl_Layer and gl_ViewportIndex. GL 4.6 table 23.65 makes
+            // GL_UNDEFINED_VERTEX a legal answer for both, and it is the honest default - naming
+            // a convention is a statement about behaviour, so a backend that does not pin one
+            // must not claim it does. DirectGLES fills the layer one from the ES 3.2 query and
+            // the viewport one from GL_OES_viewport_array, and leaves UNDEFINED where the
+            // capability is absent: without the viewport array extension only viewport 0 is ever
+            // rasterized, so no convention selects anything. DirectVulkan keeps UNDEFINED for
+            // both - which vertex provokes is decided per pipeline by
+            // VulkanRenderer::SelectProvokingVertexMode out of VK_EXT_provoking_vertex,
+            // provokingVertexModePerPipeline and the topology, so no single convention is true
+            // of the backend.
+            GLenum LayerProvokingVertex = GL_UNDEFINED_VERTEX;
+            GLenum ViewportIndexProvokingVertex = GL_UNDEFINED_VERTEX;
             Int MaxViewportWidth = 16384;
             Int MaxViewportHeight = 16384;
             Float ViewportBoundsRangeMin = 0.0f;

MobileGL/MG_Backend/DirectGLES/BackendObject_DirectGLES.cpp

@@ -8,6 +8,7 @@
 
 #include "BackendObject_DirectGLES.h"
 #include "MG_Backend/BackendObject.h"
+#include "MG_Backend/BackendObjects.h"
 #include <MG_Backend/DirectGLES/DirectGLES.h>
 #include <MG_Backend/DirectGLES/Managers.h>
 #include <MG_Backend/DirectGLES/Utils.h>
@@ -212,7 +213,10 @@ namespace MobileGL::MG_Backend::DirectGLES {
             if (options & PixelFormatNormalizeOptionBit::NoThreeChannelRenderTarget) {
                 reasons.push_back("no colour-renderable three-channel format on OpenGL ES");
             }
-            if (options & PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget) {
+            // A format is either 8- or 16-bit signed normalized, so at most one of the two ever
+            // survives GetApplicablePixelFormatNormalizeOptions and the reason is not duplicated.
+            if ((options & PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget) ||
+                (options & PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget)) {
                 reasons.push_back("EXT_render_snorm not supported");
             }
 
@@ -406,9 +410,12 @@ namespace MobileGL::MG_Backend::DirectGLES {
             return complete;
         }
 
+        // `samples` only reaches the multisample targets; every other target ignores it. The
+        // descending sample walk (ProbeTextureSampleCounts) reuses this whole routine rather than
+        // repeating the gen/bind/completeness/delete dance.
         Bool ProbeTexture(const MG_External::GLESFunctionsTable& gl, TextureTarget target, GLenum internalFormat,
                           GLenum imageFormat, GLenum imageType, TextureInternalFormat logicalFormat,
-                          Bool* outRenderable) {
+                          Bool* outRenderable, Int samples = 1) {
             if (!IsGLESProbeTextureTarget(target) || !gl.glGenTextures || !gl.glBindTexture || !gl.glDeleteTextures) {
                 return false;
             }
@@ -428,10 +435,11 @@ namespace MobileGL::MG_Backend::DirectGLES {
 
             const Bool isMultisample = IsGLESProbeMultisampleTarget(target);
             if (isMultisample) {
+                const auto probeSamples = static_cast<GLsizei>(std::max(samples, 1));
                 if (target == TextureTarget::Texture2DMultisample && gl.glTexStorage2DMultisample) {
-                    gl.glTexStorage2DMultisample(glTarget, 1, internalFormat, 1, 1, GL_TRUE);
+                    gl.glTexStorage2DMultisample(glTarget, probeSamples, internalFormat, 1, 1, GL_TRUE);
                 } else if (target == TextureTarget::Texture2DMultisampleArray && gl.glTexStorage3DMultisample) {
-                    gl.glTexStorage3DMultisample(glTarget, 1, internalFormat, 1, 1, 1, GL_TRUE);
+                    gl.glTexStorage3DMultisample(glTarget, probeSamples, internalFormat, 1, 1, 1, GL_TRUE);
                 } else {
                     gl.glBindTexture(glTarget, static_cast<GLuint>(previousBinding));
                     gl.glDeleteTextures(1, &texture);
@@ -527,6 +535,29 @@ namespace MobileGL::MG_Backend::DirectGLES {
             return sampleCounts;
         }
 
+        // The multisample TEXTURE twin of ProbeRenderbufferSampleCounts. It used to be a
+        // hardcoded {1}, which made glGetInternalformativ(GL_SAMPLES) claim a one-sample maximum
+        // for every format on the multisample targets even where glTexImage2DMultisample happily
+        // accepts four - GL 4.6 core 8.8 makes that query the definition of the maximum, so the
+        // two answers cannot both be right. Completeness is required at every count, exactly as
+        // the renderbuffer walk requires it; the caller only reaches here once the one-sample
+        // probe has already succeeded, so 1 terminates the list without being re-probed.
+        Vector<Int> ProbeTextureSampleCounts(const MG_External::GLESFunctionsTable& gl, TextureTarget target,
+                                             GLenum internalFormat, GLenum imageFormat, GLenum imageType,
+                                             TextureInternalFormat logicalFormat, Int maxSamples) {
+            Vector<Int> sampleCounts;
+            for (Int samples = std::max(maxSamples, 1); samples > 1; samples >>= 1) {
+                Bool renderable = false;
+                const Bool created = ProbeTexture(gl, target, internalFormat, imageFormat, imageType, logicalFormat,
+                                                  &renderable, samples);
+                if (created && renderable) {
+                    sampleCounts.push_back(samples);
+                }
+            }
+            sampleCounts.push_back(1);
+            return sampleCounts;
+        }
+
         void PopulateFormatCapabilitiesImpl(const MG_External::GLESFunctionsTable& gl,
                                             const MG_External::GLESCapabilities& capabilities,
                                             FormatCapabilityCache& cache) {
@@ -627,7 +658,11 @@ namespace MobileGL::MG_Backend::DirectGLES {
                             AddFullFormatCaps(cache, targetIndex, formatIndex,
                                               BuildTextureCapsFromProbe(logicalFormat, target, nativeRenderable));
                             if (IsGLESProbeMultisampleTarget(target)) {
-                                cache.SampleCounts[targetIndex][formatIndex] = {1};
+                                const Int maxSamples =
+                                    GetGLESFormatMaxSamples(capabilities, logicalFormat, nativeInfo.ImageFormat);
+                                cache.SampleCounts[targetIndex][formatIndex] = ProbeTextureSampleCounts(
+                                    gl, probeTarget, nativeInfo.InternalFormat, nativeInfo.ImageFormat,
+                                    nativeInfo.ImageType, logicalFormat, maxSamples);
                             }
                         }
                         shouldProbeFallback = !nativeCreated || !nativeRenderable;
@@ -645,7 +680,11 @@ namespace MobileGL::MG_Backend::DirectGLES {
                                 LogGLESFormatCaveat(logicalFormat, targetIndex, fallbackInfo);
                             }
                             if (IsGLESProbeMultisampleTarget(target)) {
-                                cache.SampleCounts[targetIndex][formatIndex] = {1};
+                                const Int maxSamples =
+                                    GetGLESFormatMaxSamples(capabilities, logicalFormat, fallbackInfo.ImageFormat);
+                                cache.SampleCounts[targetIndex][formatIndex] = ProbeTextureSampleCounts(
+                                    gl, probeTarget, fallbackInfo.InternalFormat, fallbackInfo.ImageFormat,
+                                    fallbackInfo.ImageType, logicalFormat, maxSamples);
                             }
                         }
                     }
@@ -747,6 +786,29 @@ namespace MobileGL::MG_Backend::DirectGLES {
         PopulateFormatCapabilitiesImpl(gl, capabilities, cache);
     }
 
+    Int ClampSamplesToBackendSupport(SizeT targetIndex, TextureInternalFormat logicalFormat, GLenum imageFormat,
+                                     Int samples) {
+        if (samples <= 1) {
+            return samples;
+        }
+
+        Int maxSamples = 0;
+        const SizeT formatIndex = static_cast<SizeT>(logicalFormat);
+        if (pActiveBackendObject && targetIndex < kFormatCapabilityTargetCount &&
+            formatIndex < kFormatCapabilityFormatCount) {
+            // Descending, so the head is the largest count this device actually allocated.
+            const Vector<Int>& probedCounts =
+                pActiveBackendObject->GetFormatCapabilities().SampleCounts[targetIndex][formatIndex];
+            if (!probedCounts.empty()) {
+                maxSamples = probedCounts.front();
+            }
+        }
+        if (maxSamples <= 0) {
+            maxSamples = GetGLESFormatMaxSamples(g_GLESCapabilities, logicalFormat, imageFormat);
+        }
+        return std::min(samples, std::max(maxSamples, 1));
+    }
+
     BackendObject_DirectGLES::~BackendObject_DirectGLES() {
         DestroyEGLContext();
     }
@@ -1107,6 +1169,12 @@ namespace MobileGL::MG_Backend::DirectGLES {
             // geometry shader's amplification.
             funcsTable.GL.BeginXfbPrimitivesQuery = BeginXfbPrimitivesQuery;
             funcsTable.GL.EndXfbPrimitivesQuery = EndXfbPrimitivesQuery;
+            // ...but where it CAN see the whole capture - no geometry stage - the frontend's
+            // own count is the desktop-exact one and the ES driver's is only as good as the
+            // vendor made it (Adreno doubles PRIMITIVES_WRITTEN for a vertex-only capture that
+            // follows a large render pass). The query above stays installed: it is still what
+            // answers an amplifying span, and PRIMITIVES_GENERATED always.
+            funcsTable.GL.PrefersCpuXfbPrimitiveAccounting = true;
             funcsTable.GL.IsQueryResultAvailable = IsQueryResultAvailable;
             funcsTable.GL.GetQueryResult64 = GetQueryResult64;
             funcsTable.GL.DeleteBackendQuery = DeleteBackendQuery;
@@ -1186,9 +1254,31 @@ namespace MobileGL::MG_Backend::DirectGLES {
                      static_cast<Int>(MG_State::GLState::VertexArrayObject::MAX_VERTEX_ATTRIBS));
         m_dynamicParameters.MaxComputeShaderStorageBlocks = m_GLESCapabilities.MaxComputeShaderStorageBlocks;
         m_dynamicParameters.MaxCombinedShaderStorageBlocks = m_GLESCapabilities.MaxCombinedShaderStorageBlocks;
+        // Per-stage storage-block counts, forwarded from the host driver rather than invented.
+        // A stage the driver cannot serve reports 0, which is a legal answer everywhere these
+        // limits appear (GL 4.6 table 23.64, ES 3.2 table 21.44 - the minimum is 0 for every
+        // graphics stage except fragment) and is the only answer that lets an application take
+        // its own fallback instead of building a program the driver will refuse to link. The
+        // stage limit cannot exceed the combined limit or the number of binding points there
+        // are to bind buffers to, so clamp to both.
+        const auto clampStageStorageBlocks = [this](Int stageLimit) {
+            return std::min({std::max(stageLimit, 0), std::max(m_dynamicParameters.MaxCombinedShaderStorageBlocks, 0),
+                             std::max(m_dynamicParameters.MaxShaderStorageBufferBindings, 0)});
+        };
+        m_dynamicParameters.MaxShaderStorageBufferBindings = m_GLESCapabilities.MaxShaderStorageBufferBindings;
+        m_dynamicParameters.MaxVertexShaderStorageBlocks =
+            clampStageStorageBlocks(m_GLESCapabilities.MaxVertexShaderStorageBlocks);
+        m_dynamicParameters.MaxTessControlShaderStorageBlocks =
+            clampStageStorageBlocks(m_GLESCapabilities.MaxTessControlShaderStorageBlocks);
+        m_dynamicParameters.MaxTessEvaluationShaderStorageBlocks =
+            clampStageStorageBlocks(m_GLESCapabilities.MaxTessEvaluationShaderStorageBlocks);
+        m_dynamicParameters.MaxGeometryShaderStorageBlocks =
+            clampStageStorageBlocks(m_GLESCapabilities.MaxGeometryShaderStorageBlocks);
+        m_dynamicParameters.MaxFragmentShaderStorageBlocks =
+            clampStageStorageBlocks(m_GLESCapabilities.MaxFragmentShaderStorageBlocks);
         m_dynamicParameters.MaxComputeUniformBlocks = m_GLESCapabilities.MaxComputeUniformBlocks;
         m_dynamicParameters.MaxComputeWorkGroupInvocations = m_GLESCapabilities.MaxComputeWorkGroupInvocations;
-        m_dynamicParameters.MaxShaderStorageBufferBindings = m_GLESCapabilities.MaxShaderStorageBufferBindings;
+        // (MaxShaderStorageBufferBindings is assigned above, before the per-stage clamp reads it.)
         // This is the number glGetIntegerv(GL_MAX_TEXTURE_BUFFER_SIZE) hands the application, and
         // on a host without buffer textures it is knowingly a floor MobileGL cannot honour rather
         // than a driver answer (m_GLESCapabilities.MaxTextureBufferSizeIsDriverReported says
@@ -1249,6 +1339,13 @@ namespace MobileGL::MG_Backend::DirectGLES {
         m_dynamicParameters.MaxColorAttachments = m_GLESCapabilities.MaxColorAttachments;
         m_dynamicParameters.MaxClipDistances = m_GLESCapabilities.MaxClipDistances;
         m_dynamicParameters.MaxViewports = m_GLESCapabilities.MaxViewports;
+        // Whatever the driver said about which vertex supplies gl_Layer, and GL_UNDEFINED_VERTEX
+        // for gl_ViewportIndex on every driver without GL_OES_viewport_array - which is both test
+        // devices. That is not a shortfall being hidden: without the extension only viewport 0 is
+        // ever rasterized, so no vertex "selects" a viewport index and naming a convention would
+        // describe behaviour this backend does not implement.
+        m_dynamicParameters.LayerProvokingVertex = m_GLESCapabilities.LayerProvokingVertex;
+        m_dynamicParameters.ViewportIndexProvokingVertex = m_GLESCapabilities.ViewportIndexProvokingVertex;
         m_dynamicParameters.MaxViewportWidth = m_GLESCapabilities.MaxViewportWidth;
         m_dynamicParameters.MaxViewportHeight = m_GLESCapabilities.MaxViewportHeight;
         m_dynamicParameters.ViewportBoundsRangeMin = m_GLESCapabilities.ViewportBoundsRangeMin;

MobileGL/MG_Backend/DirectGLES/BackendObject_DirectGLES.h

@@ -18,6 +18,16 @@ namespace MobileGL::MG_Backend::DirectGLES {
                                     const MG_External::GLESCapabilities& capabilities,
                                     FormatCapabilityCache& cache);
 
+    // Clamps a requested sample count down to what the ES driver can really deliver for this
+    // format on this format-capability target: the probed per-format list when there is one, the
+    // driver's per-class GL_MAX_*_SAMPLES otherwise. The frontend deliberately validates against
+    // the count MobileGL advertises instead (GL_Getter's GetAdvertisedMaxSamples), which on a
+    // driver reporting GL_MAX_INTEGER_SAMPLES 1 is higher than the driver accepts, so every ES
+    // allocation call has to come through here. The shadow state keeps the requested count, so
+    // GL_TEXTURE_SAMPLES and framebuffer completeness still answer what the application asked for.
+    Int ClampSamplesToBackendSupport(SizeT targetIndex, TextureInternalFormat logicalFormat, GLenum imageFormat,
+                                     Int samples);
+
     class BackendObject_DirectGLES : public BackendObject {
     public:
         ~BackendObject_DirectGLES() override;

MobileGL/MG_Backend/DirectGLES/DirectGLES.cpp

@@ -300,10 +300,32 @@ namespace MobileGL::MG_Backend::DirectGLES {
             Clear();
         }
 #else
-        void ErrorLopper::Loop(const std::function<void(GLenum)>& func) {}
-        void ErrorLopper::Clear() {}
-        ErrorLopper::ErrorLopper() = default;
-        ErrorLopper::~ErrorLopper() = default;
+        // Error HYGIENE is not a debugging feature: every site that brackets a risky ES call with
+        // Clear()/Loop() relied on these to empty the driver's queue, and compiling them to
+        // nothing left whatever the driver raised sitting there for an unrelated later
+        // `glGetError() == GL_NO_ERROR` probe to read as its own failure. The callback stays
+        // unused because MGLOG_D is compiled out at this level, but the queue still gets drained.
+        // Bounded like DrainESErrors: a driver that never returns GL_NO_ERROR (a lost context is
+        // the usual way) must not spin here.
+        constexpr Int kMaxDrainedESErrors = 32;
+
+        void ErrorLopper::Loop(const std::function<void(GLenum)>& func) {
+            static_cast<void>(func);
+            for (Int i = 0; i < kMaxDrainedESErrors && g_GLESFuncs.glGetError() != GL_NO_ERROR; ++i) {
+            }
+        }
+
+        void ErrorLopper::Clear() {
+            for (Int i = 0; i < kMaxDrainedESErrors && g_GLESFuncs.glGetError() != GL_NO_ERROR; ++i) {
+            }
+        }
+
+        ErrorLopper::ErrorLopper() {
+            Clear();
+        }
+        ErrorLopper::~ErrorLopper() {
+            Clear();
+        }
 #endif
 
 #if MOBILEGL_LOG_ACTIVE_LEVEL <= MOBILEGL_LOG_LEVEL_DEBUG
@@ -373,6 +395,50 @@ namespace MobileGL::MG_Backend::DirectGLES {
             }
         }
 
+        void SyncAtomicCounterBuffers(const Vector<Int>& glBindings, Int esslBindingTop) {
+#ifdef TRACY_ENABLE
+            ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
+#endif
+            const SizeT pointCount = MG_State::pGLContext->GetBufferBindingPointCount(BufferTarget::AtomicCounter);
+            for (const Int glBinding : glBindings) {
+                if (glBinding < 0 || static_cast<SizeT>(glBinding) >= pointCount) continue;
+                const Int esslBinding = esslBindingTop - glBinding;
+                // Already diagnosed once when the block was transpiled; nothing was bound to it
+                // there either, so there is nothing to unbind here.
+                if (esslBinding < 0) continue;
+                auto& point = MG_State::pGLContext->GetBufferBindingPoint(BufferTarget::AtomicCounter,
+                                                                          static_cast<Uint>(glBinding));
+                auto& obj = point.GetBoundObject();
+                if (!obj) {
+                    BindBufferBaseCached(GL_SHADER_STORAGE_BUFFER, static_cast<Uint>(esslBinding), 0);
+                    continue;
+                }
+
+                auto* backendResource = EnsureBufferResource(obj);
+                if (!backendResource || backendResource->id == 0) {
+                    MGLOG_E_ONCE("No backend buffer found for atomic counter binding point %d.", glBinding);
+                    continue;
+                }
+
+                const auto& range = point.GetRange();
+                if (range.start == 0 && range.end >= obj->GetSize()) {
+                    BindBufferBaseCached(GL_SHADER_STORAGE_BUFFER, static_cast<Uint>(esslBinding),
+                                         backendResource->id);
+                } else {
+                    const auto start = std::min(range.start, obj->GetSize());
+                    const auto end = std::min(range.end, obj->GetSize());
+                    BindBufferRangeCached(GL_SHADER_STORAGE_BUFFER, static_cast<Uint>(esslBinding),
+                                          backendResource->id, static_cast<GLintptr>(start),
+                                          static_cast<GLsizeiptr>(end - start));
+                }
+                // The whole point of a counter is that the shader INCREMENTS it, and every
+                // conformance case reads the result back with glMapBufferRange or
+                // glGetBufferSubData - which serve the frontend's CPU shadow until the buffer is
+                // flagged (BufferObject::SyncGpuWrites), exactly as for a storage buffer.
+                obj->MarkGpuWritten();
+            }
+        }
+
         void SyncBoundBuffer(BufferTarget target, GLenum glTarget) {
 #ifdef TRACY_ENABLE
             ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
@@ -1319,6 +1385,16 @@ namespace MobileGL::MG_Backend::DirectGLES {
         // is stored as an ES 2D array (MapToBackendTextureTarget), and so is layerable; asking
         // the state target instead answered "no" for it and pinned every 1D-array image binding
         // to layer 0, whatever the application passed.
+        //
+        // `layer` travels with the answer, because GL 4.6 core 8.26 (and ES 3.2 8.22, word for
+        // word) makes them one rule: "If the texture identified by texture does not have
+        // multiple layers or faces, the entire texture level is bound, regardless of the values
+        // of layered and layer." REGARDLESS means ignored - not clamped, and not an error - so
+        // the driver must not be handed a layer index the texture has no room for. Adreno takes
+        // such a request literally and leaves the image unit reading zero, which is what failed
+        // KHR-GL42.bind_image_texture.single_layer's layer:1 rows on GL_TEXTURE_2D and on the
+        // GL_TEXTURE_1D that is stored as one. Normalizing here and not in the frontend shadow
+        // is deliberate: GL_IMAGE_BINDING_LAYER must keep echoing what the application passed.
         static Bool SupportsLayeredImageBinding(TextureTarget target) {
             const TextureTarget backendTarget = TextureImpl::MapToBackendTextureTarget(target);
             return backendTarget == TextureTarget::Texture3D || backendTarget == TextureTarget::TextureCubeMap ||
@@ -1362,22 +1438,33 @@ namespace MobileGL::MG_Backend::DirectGLES {
             }
         }
 
+        // Highest image unit that has ever been given a texture, plus one. Maintained by the
+        // single funnel below, so it is a sound "no draw in this context can be reading an image"
+        // test: nothing reaches an image unit without going through SyncImageTextureBinding.
+        // Almost every program (every Minecraft draw) leaves it at zero, which is what keeps the
+        // draw-path staleness check below at one integer test.
+        static Uint g_imageUnitHighWaterMark = 0;
+
         void SyncImageTextureBinding(Uint unit) {
 #ifdef TRACY_ENABLE
             ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
             auto& imageBinding = MG_State::pGLContext->GetImageTextureBinding(static_cast<Int>(unit));
             TrackWritableImageBufferUnit(unit, IsWritableImageBufferTexture(imageBinding));
+            if (imageBinding.Texture && unit + 1 > g_imageUnitHighWaterMark) {
+                g_imageUnitHighWaterMark = unit + 1;
+            }
             if (!imageBinding.Texture) {
                 g_GLESFuncs.glBindImageTexture(unit, 0, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA8);
                 return;
             }
 
             auto& backendTexture = SyncTextureObjectToBackend(imageBinding.Texture, true);
-            const GLboolean layered =
-                SupportsLayeredImageBinding(imageBinding.Texture->GetTarget()) ? imageBinding.Layered : GL_FALSE;
+            const Bool layerable = SupportsLayeredImageBinding(imageBinding.Texture->GetTarget());
+            const GLboolean layered = layerable ? imageBinding.Layered : GL_FALSE;
+            const GLint layer = layerable ? imageBinding.Layer : 0;
             g_GLESFuncs.glBindImageTexture(unit, backendTexture->GetBackendTextureId(), imageBinding.Level,
-                                           layered, imageBinding.Layer, imageBinding.Access, imageBinding.Format);
+                                           layered, layer, imageBinding.Access, imageBinding.Format);
         }
 
         // A buffer texture bound to a WRITABLE image unit is a buffer the shader is about to
@@ -1420,6 +1507,40 @@ namespace MobileGL::MG_Backend::DirectGLES {
                 SyncImageTextureBinding(unit);
             }
         }
+
+        // What the draw path last swept the image units against. A draw never swept them at all:
+        // an image unit was established once, eagerly, by glBindImageTexture and never revisited.
+        // That is stale the moment the texture behind it is re-specified with a new size or
+        // format, because ES 3.1 only allows IMMUTABLE storage on an image unit
+        // (SyncTextureObjectToBackend's imageBindableStorageRequired), immutable storage cannot be
+        // redefined, and so the re-spec MINTS A NEW ES TEXTURE NAME - leaving the unit pointing at
+        // the deleted one and imageSize() reporting the old dimensions
+        // (KHR-GL43.shader_image_size.advanced-changeSize).
+        static Uint64 g_imageSweepContextId = 0;
+        static Uint64 g_imageSweepSamplingGeneration = 0;
+        static Uint g_imageSweepBackendContextGeneration = 0;
+        static Bool g_imageSweepValid = false;
+
+        // The sweep is a glBindImageTexture per unit, so it must not run per draw: the gate is the
+        // frontend's sampling-resolution generation, which TextureObjectBase::BumpShapeVersion
+        // moves on exactly the shape and format changes that can force the re-mint. Deliberately
+        // NOT the backend-side re-mint counter (g_attachmentBackendIdGeneration's sibling would be
+        // the obvious choice): a texture that is bound ONLY to an image unit is re-minted inside
+        // this very sweep, so a backend-side trigger would be bumped after the gate had already
+        // declined to run it.
+        void SyncImageTextureBindingsForDraw(const DrawTextureSyncKeys& keys) {
+            if (g_imageUnitHighWaterMark == 0) return;
+            if (g_imageSweepValid && g_imageSweepContextId == keys.contextId &&
+                g_imageSweepSamplingGeneration == keys.samplingGeneration &&
+                g_imageSweepBackendContextGeneration == g_backendContextGeneration) {
+                return;
+            }
+            SyncImageTextureBindings();
+            g_imageSweepContextId = keys.contextId;
+            g_imageSweepSamplingGeneration = keys.samplingGeneration;
+            g_imageSweepBackendContextGeneration = g_backendContextGeneration;
+            g_imageSweepValid = true;
+        }
     } // namespace TextureImpl
 
     namespace FramebufferImpl {
@@ -2363,6 +2484,11 @@ namespace MobileGL::MG_Backend::DirectGLES {
                                           syncBit & DrawSyncBit::IndirectBuffer);
         VertexArrayImpl::SyncCurrentVAO(currentVAO, vaoTwin);
         TextureImpl::SyncNeccessaryTextures(textureKeys);
+        // A draw reads and writes through its image units too, so the unit bindings have to be
+        // as current as the sampled ones. Gated (see the sweep): a program with no image binding
+        // pays one integer test, and one with images re-issues them only when a texture shape
+        // moved under them.
+        TextureImpl::SyncImageTextureBindingsForDraw(textureKeys);
         // A draw writes through its image units too - the conformance case that found this
         // stores into a buffer texture from the FRAGMENT stage, not from a dispatch.
         TextureImpl::MarkWritableImageBufferTexturesGpuWritten();
@@ -2882,6 +3008,16 @@ namespace MobileGL::MG_Backend::DirectGLES {
                     }
                 }
 
+                // Atomic counter buffers. Bound here rather than beside the storage-buffer sync
+                // in SyncNeccessaryBuffers because the reserved slot the transpiled ESSL reads
+                // them at is PROGRAM state: it is `top - GL binding` for the counter blocks THIS
+                // program declares, and no other program's blocks live there. Both the draw and
+                // the dispatch path reach this, which is what a compute-shader counter needs.
+                if (!backendProgram.GetAtomicCounterBindings().empty()) {
+                    BufferImpl::SyncAtomicCounterBuffers(backendProgram.GetAtomicCounterBindings(),
+                                                         backendProgram.GetAtomicCounterEsslBindingTop());
+                }
+
                 {
 #ifdef TRACY_ENABLE
                     ZoneScopedNC("BindSamplerUnit", TRACY_ZONECOLOR_BACKEND);
@@ -3845,11 +3981,28 @@ namespace MobileGL::MG_Backend::DirectGLES {
                                       sizeof(DrawArraysIndirectCommand), "DrawArraysIndirect");
     }
 
-    static void DrainBlitErrors() {
-        while (g_GLESFuncs.glGetError() != GL_NO_ERROR) {
+    // Empties the ES driver's error queue, BOUNDED. A driver that never answers GL_NO_ERROR - a
+    // lost context is the usual way, and GL_CONTEXT_LOST is allowed to keep coming back - would
+    // otherwise spin an unbounded drain forever inside whichever GL entry point happened to be
+    // cleaning up, which is how a GPU reset reads as an unkillable process whose log simply
+    // stops. A healthy context cannot queue anywhere near the cap, so reaching it IS the
+    // diagnostic. Every drain in this backend goes through here so the bound cannot drift apart
+    // between them.
+    static constexpr Int kMaxDrainedGLErrors = 32;
+
+    static void DrainDriverErrors(const char* site) {
+        Int drained = 0;
+        while (drained < kMaxDrainedGLErrors && g_GLESFuncs.glGetError() != GL_NO_ERROR) {
+            ++drained;
+        }
+        if (drained == kMaxDrainedGLErrors) {
+            MGLOG_E_ONCE("%s: the ES driver still reported errors after %d drains - the context is most likely lost",
+                         site, kMaxDrainedGLErrors);
         }
     }
 
+    static void DrainBlitErrors() { DrainDriverErrors("BlitFramebuffer"); }
+
     // Sized internal format of the currently bound READ framebuffer's read colour
     // attachment, 0 when it cannot be determined.
     static GLenum QueryReadColorAttachmentInternalFormat() {
@@ -4624,16 +4777,46 @@ namespace MobileGL::MG_Backend::DirectGLES {
             }
             return;
         }
-        if (readSamples <= 0 || drawSamples > 0 || (mask & GL_COLOR_BUFFER_BIT) == 0) {
-            return;
-        }
-        if (ResolveThenBlit(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, filter) &&
-            (mask & ~static_cast<GLbitfield>(GL_COLOR_BUFFER_BIT)) != 0) {
-            DrainBlitErrors();
-            g_GLESFuncs.glBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1,
-                                          mask & ~static_cast<GLbitfield>(GL_COLOR_BUFFER_BIT), filter);
+        // The combined call raised an error, so by GL 4.6 2.3.1 it wrote nothing at all: BOTH
+        // aspect groups still owe their copy, and each has to be retried on its own. Re-issuing
+        // the depth/stencil half only as a rider on a SUCCESSFUL colour resolve dropped it
+        // silently whenever the colour half could not be emulated - and on a framebuffer whose
+        // only attachment is depth it never can, because the colour emulation has no attachment
+        // to take a format from (KHR-GL33.framebuffer_blit's depth config test blits
+        // COLOR|DEPTH|STENCIL across depth-only framebuffers and kept reading the clear value).
+        const GLbitfield colourBit = mask & static_cast<GLbitfield>(GL_COLOR_BUFFER_BIT);
+        const GLbitfield dsBits = mask & static_cast<GLbitfield>(GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+        // The colour group's one emulation is the multisample resolve that also converts format,
+        // which is the shape this names. It used to double as an early-out for the whole
+        // function, which is what cost a depth-only mask its single-aspect retry.
+        const Bool multisampleResolve = readSamples > 0 && drawSamples <= 0;
+        if (colourBit != 0) {
             DrainBlitErrors();
+            g_GLESFuncs.glBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, colourBit, filter);
+            if (g_GLESFuncs.glGetError() != GL_NO_ERROR) {
+                const Bool emulated =
+                    multisampleResolve &&
+                    ResolveThenBlit(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, filter);
+                if (!emulated) {
+                    MGLOG_E_ONCE("BlitFramebuffer: the colour aspect was dropped - the driver rejected it on its "
+                                 "own and no emulation applies");
+                }
+            }
         }
+        if (dsBits != 0) {
+            DrainBlitErrors();
+            g_GLESFuncs.glBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, dsBits, filter);
+            if (g_GLESFuncs.glGetError() != GL_NO_ERROR) {
+                // Nothing to fall back on yet: ResolveThenBlit is colour-only and the replicate
+                // pass runs in the opposite direction, so a driver that declines a multisample
+                // depth/stencil resolve leaves the destination holding its clear value. The log
+                // is the whole diagnostic - the frontend performs no validation of its own, so
+                // this never reaches the application as a GL error.
+                MGLOG_E_ONCE("BlitFramebuffer: the depth/stencil aspect was dropped - the driver rejected it on "
+                             "its own and no emulation applies");
+            }
+        }
+        DrainBlitErrors();
     }
 
     void BlitFramebuffer(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1, GLint dstX0, GLint dstY0, GLint dstX1,
@@ -4990,9 +5173,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
         return false;
     }
 
-    static void ClearGLErrors() {
-        while (g_GLESFuncs.glGetError() != GL_NO_ERROR) {}
-    }
+    static void ClearGLErrors() { DrainDriverErrors("DirectGLES"); }
 
     // Binds a guaranteed-complete 1x1 scratch framebuffer at both targets for the
     // scope (GenerateMipmap must respecify texture storage while no incomplete
@@ -5605,15 +5786,27 @@ namespace MobileGL::MG_Backend::DirectGLES {
         g_GLESFuncs.glDispatchComputeIndirect(indirect);
     }
 
+    // An atomic counter is a shader storage block by the time it reaches the ES driver (glslang
+    // lowers every atomic_uint onto one), so an application that asks only for the counter
+    // barrier is asking about memory the driver knows as storage-buffer memory. Ordering one
+    // does not oblige a driver to order the other, so the counter bit implies the storage bit
+    // here - which is what the lowering costs and the only place it can be paid.
+    static GLbitfield LowerAtomicCounterBarrierBits(GLbitfield barriers) {
+        if ((barriers & GL_ATOMIC_COUNTER_BARRIER_BIT) != 0) {
+            barriers |= GL_SHADER_STORAGE_BARRIER_BIT;
+        }
+        return barriers;
+    }
+
     void MemoryBarrier(GLbitfield barriers) {
-        g_GLESFuncs.glMemoryBarrier(barriers);
+        g_GLESFuncs.glMemoryBarrier(LowerAtomicCounterBarrierBits(barriers));
         if (g_GLESCapabilities.IsAngleRenderer) {
             g_GLESFuncs.glFlush();
         }
     }
 
     void MemoryBarrierByRegion(GLbitfield barriers) {
-        g_GLESFuncs.glMemoryBarrierByRegion(barriers);
+        g_GLESFuncs.glMemoryBarrierByRegion(LowerAtomicCounterBarrierBits(barriers));
     }
 
     // One endpoint of a glCopyImageSubData, expressed the way the ES driver stores it.
@@ -5630,27 +5823,87 @@ namespace MobileGL::MG_Backend::DirectGLES {
     // The 1D-array case is not just a rename: GL addresses its layers with y/height while the
     // ES 2D array that backs it addresses them with z/depth, so the two axes swap with the
     // target.
+    //
+    // GL_RENDERBUFFER is the exception that must NOT be translated: ES 3.2 core (and
+    // GL_EXT_copy_image) take it as a srcTarget/dstTarget verbatim, while
+    // ConvertGLEnumToTextureTarget answers Unknown for it and the translation below would hand
+    // the driver GL_UNKNOWN_MGL.
     struct GLESCopyImageEndpoint {
         GLenum target = GL_TEXTURE_2D;
+        // Exactly one of the two is set. The backend object is kept rather than its id, because
+        // the id is only stable until the OTHER endpoint syncs (a sync can re-mint a texture),
+        // so it is read at the point of use.
+        SharedPtr<TextureImpl::BackendTextureObject> texture;
+        SharedPtr<RenderbufferImpl::BackendRenderbufferObject> renderbuffer;
         GLint x = 0;
         GLint y = 0;
         GLint z = 0;
+
+        Bool IsRenderbuffer() const { return renderbuffer != nullptr; }
+        GLuint Name() const {
+            if (renderbuffer) return renderbuffer->GetBackendRenderbufferId();
+            return texture ? texture->GetBackendTextureId() : 0u;
+        }
     };
 
-    static GLESCopyImageEndpoint MakeGLESCopyImageEndpoint(GLenum appTarget, GLint x, GLint y, GLint z) {
-        const TextureTarget stateTarget = MG_Util::ConvertGLEnumToTextureTarget(appTarget);
-        GLESCopyImageEndpoint endpoint{};
-        endpoint.target = TextureImpl::ConvertTextureTargetToBackendGLEnum(stateTarget);
-        if (stateTarget == TextureTarget::Texture1DArray) {
-            endpoint.x = x;
-            endpoint.y = 0;
-            endpoint.z = y;
-            return endpoint;
+    // The renderbuffer twin of TextureImpl::SyncTextureObjectToBackend: the same
+    // find-or-create-then-sync the framebuffer attachment walk does (see SyncAttachmentObject),
+    // reachable from a path that has a renderbuffer but no framebuffer.
+    static SharedPtr<RenderbufferImpl::BackendRenderbufferObject> SyncRenderbufferObjectToBackend(
+        const SharedPtr<MG_State::GLState::RenderbufferObject>& renderbufferObject) {
+        if (!renderbufferObject) return nullptr;
+        SharedPtr<RenderbufferImpl::BackendRenderbufferObject> backendRenderbufferObject;
+        if (auto* slot = RenderbufferImpl::g_backendRenderbufferObjects.Find(renderbufferObject.get())) {
+            backendRenderbufferObject = *slot;
+        } else {
+            auto& newSlot = RenderbufferImpl::g_backendRenderbufferObjects.GetOrCreate(renderbufferObject);
+            if (!newSlot) {
+                newSlot = MakeShared<RenderbufferImpl::BackendRenderbufferObject>();
+            }
+            backendRenderbufferObject = newSlot;
         }
-        endpoint.x = x;
-        endpoint.y = y;
-        endpoint.z = z;
-        return endpoint;
+        backendRenderbufferObject->SyncToBackend(renderbufferObject);
+        return backendRenderbufferObject;
+    }
+
+    static Bool MakeGLESCopyImageEndpoint(const CopyImageEndpoint& endpoint, GLenum appTarget, GLint x, GLint y,
+                                          GLint z, GLESCopyImageEndpoint& out) {
+        if (endpoint.IsRenderbuffer()) {
+            out.renderbuffer = SyncRenderbufferObjectToBackend(endpoint.Renderbuffer);
+            if (!out.renderbuffer) return false;
+            out.target = GL_RENDERBUFFER;
+            out.x = x;
+            out.y = y;
+            out.z = z;
+            return true;
+        }
+        // BY VALUE, not by reference. SyncTextureObjectToBackend hands back a reference to a
+        // slot inside the backend texture registry, and the second call mutates that very map:
+        // GetOrCreate indexes it (an insert relocates entries - by rehashing, and also by
+        // robin-hood displacement well under the load factor), and Find drops any
+        // entry whose state object has expired - which, with the map open-addressed and erasing
+        // by shifting the probe cluster backwards, relocates entries other than the erased one.
+        // Either way a reference taken by the first call is stale by the time the second returns,
+        // and it is read four more times below. Copying the SharedPtr costs two refcount bumps on
+        // a path that is already doing a texture copy.
+        // An endpoint that named nothing is the frontend validator's INVALID_VALUE and never
+        // reaches here - but the assertion that says so is compiled out of a release build, and
+        // SyncTextureObjectToBackend would register a null state object.
+        if (!endpoint.Texture) return false;
+        out.texture = TextureImpl::SyncTextureObjectToBackend(endpoint.Texture);
+        if (!out.texture) return false;
+        const TextureTarget stateTarget = MG_Util::ConvertGLEnumToTextureTarget(appTarget);
+        out.target = TextureImpl::ConvertTextureTargetToBackendGLEnum(stateTarget);
+        if (stateTarget == TextureTarget::Texture1DArray) {
+            out.x = x;
+            out.y = 0;
+            out.z = y;
+            return true;
+        }
+        out.x = x;
+        out.y = y;
+        out.z = z;
+        return true;
     }
 
     // The region extent swaps the same two axes for a 1D array, and does so for whichever side
@@ -5666,85 +5919,172 @@ namespace MobileGL::MG_Backend::DirectGLES {
         std::swap(height, depth);
     }
 
-    void CopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+    static TextureInternalFormat GetCopyImageEndpointFormat(const CopyImageEndpoint& endpoint) {
+        if (endpoint.IsRenderbuffer()) return endpoint.Renderbuffer->GetInternalFormat();
+        return endpoint.Texture ? endpoint.Texture->GetFormat() : TextureInternalFormat::Unknown;
+    }
+
+    // Whether this endpoint's CPU shadow can be addressed texel-exactly by the mirror below: one
+    // upload target (so not a cube map, whose six chains the z axis selects between) and layers on
+    // the z axis (GL_TEXTURE_1D_ARRAY carries them on y).
+    static Bool CanMirrorCopyImageShadow(const SharedPtr<MG_State::GLState::ITextureObject>& texture) {
+        if (!texture) return false;
+        if (texture->GetTarget() == TextureTarget::Texture1DArray) return false;
+        return texture->GetUploadTargets().size() == 1;
+    }
+
+    // glCopyImageSubData is defined as a raw texel-block move, so for a destination whose CPU
+    // shadow has to stay authoritative - a packed format with redundant encodings, where a GPU
+    // readback can only answer with RE-ENCODED words (see the verbatim branch in GetTexImage) -
+    // the same move is replayed on the shadow. Nothing is marked dirty: the driver copy already
+    // put these texels on the GPU, and flagging the level would only schedule a redundant upload
+    // back over them.
+    //
+    // Declined, leaving the shadow exactly as it was, for every shape whose bytes this cannot
+    // address exactly - a renderbuffer (no shadow at all), a cube or 1D-array endpoint, a level
+    // whose shadow is missing or not a plain texel grid, a region outside either level, or a
+    // self-copy within one level, where the row copies could overlap.
+    static void MirrorCopyImageIntoDestinationShadow(const CopyImageEndpoint& srcEndpoint, GLint srcLevel, GLint srcX,
+                                                     GLint srcY, GLint srcZ, const CopyImageEndpoint& dstEndpoint,
+                                                     GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
+                                                     GLsizei width, GLsizei height, GLsizei depth) {
+        if (!CanMirrorCopyImageShadow(srcEndpoint.Texture) || !CanMirrorCopyImageShadow(dstEndpoint.Texture)) return;
+        if (srcEndpoint.Texture == dstEndpoint.Texture && srcLevel == dstLevel) return;
+        if (width <= 0 || height <= 0 || depth <= 0) return;
+        if (srcLevel < 0 || dstLevel < 0 || srcX < 0 || srcY < 0 || srcZ < 0 || dstX < 0 || dstY < 0 || dstZ < 0) {
+            return;
+        }
+        auto* srcMipmap = MG_State::GLState::AsMipmapTexture(srcEndpoint.Texture.get());
+        auto* dstMipmap = MG_State::GLState::AsMipmapTexture(dstEndpoint.Texture.get());
+        if (!srcMipmap || !dstMipmap) return;
+
+        const auto srcUploadTarget = srcEndpoint.Texture->GetUploadTargets()[0];
+        const auto dstUploadTarget = dstEndpoint.Texture->GetUploadTargets()[0];
+        const IntVec3 srcSize = srcMipmap->GetMipmapTexelSize(srcUploadTarget, static_cast<Uint>(srcLevel));
+        const IntVec3 dstSize = dstMipmap->GetMipmapTexelSize(dstUploadTarget, static_cast<Uint>(dstLevel));
+        const SizeT srcSlices = static_cast<SizeT>(std::max(srcSize.z(), 1));
+        const SizeT dstSlices = static_cast<SizeT>(std::max(dstSize.z(), 1));
+        if (srcSize.x() <= 0 || srcSize.y() <= 0 || dstSize.x() <= 0 || dstSize.y() <= 0) return;
+        const SizeT srcTexels = static_cast<SizeT>(srcSize.x()) * static_cast<SizeT>(srcSize.y()) * srcSlices;
+        const SizeT dstTexels = static_cast<SizeT>(dstSize.x()) * static_cast<SizeT>(dstSize.y()) * dstSlices;
+        const SizeT srcBytes = srcMipmap->GetMipmapByteSize(srcUploadTarget, static_cast<Uint>(srcLevel));
+        const SizeT dstBytes = dstMipmap->GetMipmapByteSize(dstUploadTarget, static_cast<Uint>(dstLevel));
+        // A shadow that is not exactly texels x texelSize bytes is one this cannot index (a
+        // compressed blob, or a level whose allocation disagrees with its recorded extent).
+        const SizeT texelBytes = srcTexels == 0 ? 0 : srcBytes / srcTexels;
+        if (texelBytes == 0 || srcBytes != srcTexels * texelBytes || dstTexels == 0 ||
+            dstBytes != dstTexels * texelBytes) {
+            return;
+        }
+        if (static_cast<SizeT>(srcX) + width > static_cast<SizeT>(srcSize.x()) ||
+            static_cast<SizeT>(srcY) + height > static_cast<SizeT>(srcSize.y()) ||
+            static_cast<SizeT>(srcZ) + depth > srcSlices ||
+            static_cast<SizeT>(dstX) + width > static_cast<SizeT>(dstSize.x()) ||
+            static_cast<SizeT>(dstY) + height > static_cast<SizeT>(dstSize.y()) ||
+            static_cast<SizeT>(dstZ) + depth > dstSlices) {
+            return;
+        }
+
+        const auto* srcBase = static_cast<const Uint8*>(
+            srcMipmap->MapMipmapData(srcUploadTarget, static_cast<Uint>(srcLevel)));
+        auto* dstBase = static_cast<Uint8*>(dstMipmap->MapMipmapData(dstUploadTarget, static_cast<Uint>(dstLevel)));
+        if (!srcBase || !dstBase) return;
+
+        const SizeT rowBytes = static_cast<SizeT>(width) * texelBytes;
+        for (GLsizei slice = 0; slice < depth; ++slice) {
+            for (GLsizei row = 0; row < height; ++row) {
+                const SizeT srcOffset = ((static_cast<SizeT>(srcZ + slice) * static_cast<SizeT>(srcSize.y()) +
+                                          static_cast<SizeT>(srcY + row)) *
+                                             static_cast<SizeT>(srcSize.x()) +
+                                         static_cast<SizeT>(srcX)) *
+                                        texelBytes;
+                const SizeT dstOffset = ((static_cast<SizeT>(dstZ + slice) * static_cast<SizeT>(dstSize.y()) +
+                                          static_cast<SizeT>(dstY + row)) *
+                                             static_cast<SizeT>(dstSize.x()) +
+                                         static_cast<SizeT>(dstX)) *
+                                        texelBytes;
+                Memcpy(dstBase + dstOffset, srcBase + srcOffset, rowBytes);
+            }
+        }
+        MGLOG_D("CopyImageSubData: mirrored %dx%dx%d texels into the destination's CPU shadow", width, height,
+                depth);
+    }
+
+    void CopyImageSubData(const CopyImageEndpoint& srcEndpoint,
                           GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                          const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                          const CopyImageEndpoint& dstEndpoint,
                           GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                           GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
-        // BY VALUE, not by reference. SyncTextureObjectToBackend hands back a reference to a
-        // slot inside the backend texture registry, and the second call mutates that very map:
-        // GetOrCreate indexes it (an insert relocates entries - by rehashing, and also by
-        // robin-hood displacement well under the load factor), and Find drops any
-        // entry whose state object has expired - which, with the map open-addressed and erasing
-        // by shifting the probe cluster backwards, relocates entries other than the erased one.
-        // Either way a reference taken by the first call is stale by the time the second returns,
-        // and it is read four more times below. Copying the SharedPtr costs two refcount bumps on
-        // a path that is already doing a texture copy.
-        const SharedPtr<TextureImpl::BackendTextureObject> srcBackendTexture =
-            TextureImpl::SyncTextureObjectToBackend(srcTexture);
-        const SharedPtr<TextureImpl::BackendTextureObject> dstBackendTexture =
-            TextureImpl::SyncTextureObjectToBackend(dstTexture);
+        GLESCopyImageEndpoint src{};
+        GLESCopyImageEndpoint dst{};
         // The DirectVulkan half of this entry point died exactly here, on a texture whose sync
         // produced nothing - and it died in a release build, where the MOBILEGL_ASSERT that was
-        // supposed to catch it expands to nothing. The four GetBackendTextureId() calls below
-        // are the same dereference. The frontend validator is what keeps this unreachable and
-        // what reports the error the application is owed; declining is only how a future gap up
-        // there stops being a crash. See the level guard in VulkanRenderer::CopyImageSubData.
-        if (!srcBackendTexture || !dstBackendTexture) {
-            MGLOG_E_ONCE("%s: source or destination texture failed to sync; declining the copy", __func__);
+        // supposed to catch it expands to nothing. The four Name() calls below are the same
+        // dereference. The frontend validator is what keeps this unreachable and what reports
+        // the error the application is owed; declining is only how a future gap up there stops
+        // being a crash. See the level guard in VulkanRenderer::CopyImageSubData.
+        if (!MakeGLESCopyImageEndpoint(srcEndpoint, srcTarget, srcX, srcY, srcZ, src) ||
+            !MakeGLESCopyImageEndpoint(dstEndpoint, dstTarget, dstX, dstY, dstZ, dst)) {
+            MGLOG_E_ONCE("%s: source or destination image failed to sync; declining the copy", __func__);
             return;
         }
 
-        const GLESCopyImageEndpoint src = MakeGLESCopyImageEndpoint(srcTarget, srcX, srcY, srcZ);
-        const GLESCopyImageEndpoint dst = MakeGLESCopyImageEndpoint(dstTarget, dstX, dstY, dstZ);
         GLsizei copyHeight = srcHeight;
         GLsizei copyDepth = srcDepth;
         ApplyGLESCopyImageExtent(srcTarget, dstTarget, copyHeight, copyDepth);
 
-        const Bool srcIsDepth = MG_Util::IsDepthFormatInternalFormat(srcTexture->GetFormat());
-        const Bool dstIsDepth = MG_Util::IsDepthFormatInternalFormat(dstTexture->GetFormat());
-        const Bool srcStencil = MG_Util::IsStencilFormatInternalFormat(srcTexture->GetFormat());
-        const Bool dstStencil = MG_Util::IsStencilFormatInternalFormat(dstTexture->GetFormat());
-        if (srcIsDepth || dstIsDepth || srcStencil || dstStencil) {
+        const TextureInternalFormat srcFormat = GetCopyImageEndpointFormat(srcEndpoint);
+        const TextureInternalFormat dstFormat = GetCopyImageEndpointFormat(dstEndpoint);
+        // Both emulation fallbacks below are written against TEXTURE ids and texture targets, so
+        // an endpoint that is a renderbuffer takes the native ES copy - which accepts
+        // GL_RENDERBUFFER on both sides - and reports rather than mis-dispatches if the driver
+        // turns it down.
+        const Bool anyRenderbuffer = src.IsRenderbuffer() || dst.IsRenderbuffer();
+
+        const Bool srcIsDepth = MG_Util::IsDepthFormatInternalFormat(srcFormat);
+        const Bool dstIsDepth = MG_Util::IsDepthFormatInternalFormat(dstFormat);
+        const Bool srcStencil = MG_Util::IsStencilFormatInternalFormat(srcFormat);
+        const Bool dstStencil = MG_Util::IsStencilFormatInternalFormat(dstFormat);
+        if (!anyRenderbuffer && (srcIsDepth || dstIsDepth || srcStencil || dstStencil)) {
             MOBILEGL_ASSERT(srcIsDepth && dstIsDepth && !srcStencil && !dstStencil,
                             "DirectGLES CopyImageSubData only supports depth-only image copies.");
             MOBILEGL_ASSERT(src.target == GL_TEXTURE_2D && dst.target == GL_TEXTURE_2D,
                             "DirectGLES depth CopyImageSubData only supports GL_TEXTURE_2D.");
             MOBILEGL_ASSERT(src.z == 0 && dst.z == 0 && copyDepth == 1,
                             "DirectGLES depth CopyImageSubData only supports single-layer copies.");
-            BlitDepthTexture2D(srcBackendTexture->GetBackendTextureId(), srcLevel, src.x, src.y, srcWidth, copyHeight,
-                               dstBackendTexture->GetBackendTextureId(), dstLevel, dst.x, dst.y, srcWidth, copyHeight);
+            BlitDepthTexture2D(src.Name(), srcLevel, src.x, src.y, srcWidth, copyHeight,
+                               dst.Name(), dstLevel, dst.x, dst.y, srcWidth, copyHeight);
             return;
         }
 
-        if (srcTexture->GetFormat() == TextureInternalFormat::R32F ||
-            dstTexture->GetFormat() == TextureInternalFormat::R32F) {
+        if (!anyRenderbuffer &&
+            (srcFormat == TextureInternalFormat::R32F || dstFormat == TextureInternalFormat::R32F)) {
             // The single glGetError below decides the fallback dispatch, and
             // ErrorLopper::Clear is compiled out at the default log level - drain
             // with the always-live helper so a stale flag cannot misroute a
             // succeeded native copy into the 2D-only fallback.
             ClearGLErrors();
-            g_GLESFuncs.glCopyImageSubData(srcBackendTexture->GetBackendTextureId(), src.target, srcLevel, src.x, src.y, src.z,
-                                           dstBackendTexture->GetBackendTextureId(), dst.target, dstLevel, dst.x, dst.y, dst.z,
+            g_GLESFuncs.glCopyImageSubData(src.Name(), src.target, srcLevel, src.x, src.y, src.z,
+                                           dst.Name(), dst.target, dstLevel, dst.x, dst.y, dst.z,
                                            srcWidth, copyHeight, copyDepth);
             const GLenum copyImageError = g_GLESFuncs.glGetError();
             if (copyImageError == GL_NO_ERROR) {
                 return;
             }
-            MOBILEGL_ASSERT(IsColorOnlyFormat(srcTexture->GetFormat()) && IsColorOnlyFormat(dstTexture->GetFormat()),
+            MOBILEGL_ASSERT(IsColorOnlyFormat(srcFormat) && IsColorOnlyFormat(dstFormat),
                             "DirectGLES CopyImageSubData only supports color-only or depth-only copies.");
             MOBILEGL_ASSERT(src.target == GL_TEXTURE_2D && dst.target == GL_TEXTURE_2D,
                             "DirectGLES color CopyImageSubData only supports GL_TEXTURE_2D.");
             MOBILEGL_ASSERT(src.z == 0 && dst.z == 0 && copyDepth == 1,
                             "DirectGLES color CopyImageSubData only supports single-layer copies.");
-            CopyR32FTexture2D(srcBackendTexture->GetBackendTextureId(), srcLevel, src.x, src.y, srcWidth, copyHeight,
-                              dstBackendTexture->GetBackendTextureId(), dst.target, dstLevel, dst.x, dst.y);
+            CopyR32FTexture2D(src.Name(), srcLevel, src.x, src.y, srcWidth, copyHeight,
+                              dst.Name(), dst.target, dstLevel, dst.x, dst.y);
             return;
         }
 
         ClearGLErrors();
-        g_GLESFuncs.glCopyImageSubData(srcBackendTexture->GetBackendTextureId(), src.target, srcLevel, src.x, src.y, src.z,
-                                       dstBackendTexture->GetBackendTextureId(), dst.target, dstLevel, dst.x, dst.y, dst.z,
+        g_GLESFuncs.glCopyImageSubData(src.Name(), src.target, srcLevel, src.x, src.y, src.z,
+                                       dst.Name(), dst.target, dstLevel, dst.x, dst.y, dst.z,
                                        srcWidth, copyHeight, copyDepth);
         // Every error condition glCopyImageSubData has was already ruled out by the frontend
         // validator, so a driver error here is an internal invariant violation, not something
@@ -5760,6 +6100,14 @@ namespace MobileGL::MG_Backend::DirectGLES {
                          MG_Util::ConvertGLEnumToString(dst.target).c_str(),
                          MG_Util::ConvertGLEnumToString(dstTarget).c_str());
             MOBILEGL_ASSERT(false, "glCopyImageSubData failed after frontend validation accepted the request.");
+            return;
+        }
+        // The copy landed on the GPU. For a destination whose readback cannot be bit-exact the
+        // CPU shadow is what glGetTexImage answers from, so it has to follow the same move -
+        // otherwise it hands back whatever the level held before this copy.
+        if (MG_Util::PixelStoreProcessor::HasRedundantPackedEncoding(dstFormat)) {
+            MirrorCopyImageIntoDestinationShadow(srcEndpoint, srcLevel, srcX, srcY, srcZ, dstEndpoint, dstLevel,
+                                                 dstX, dstY, dstZ, srcWidth, srcHeight, srcDepth);
         }
     }
 
@@ -7050,10 +7398,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
         data = std::move(expanded);
     }
 
-    static void DrainESErrors() {
-        for (Int i = 0; i < 32 && g_GLESFuncs.glGetError() != GL_NO_ERROR; ++i) {
-        }
-    }
+    static void DrainESErrors() { DrainDriverErrors("ReadPixels"); }
 
     static GLenum QueryReadAttachmentComponentType() {
         GLint framebufferId = 0;
@@ -7339,6 +7684,149 @@ namespace MobileGL::MG_Backend::DirectGLES {
         return true;
     }
 
+    // ---- Bit-exact readback of a 32-bit packed colour level ---------------------------------------
+    //
+    // glGetTexImage of a packed format read with its OWN client type owes the application the words
+    // the image HOLDS, and neither of the two routes above can promise that once anything other than
+    // a glTexImage has written the level:
+    //
+    //   * the colour-attachment route reads GL_RGBA/GL_FLOAT and re-encodes, which canonicalizes an
+    //     RGB9_E5 shared exponent (0xf8fc0000 -> 0xe7e00000, same value, different bits) and
+    //     collapses an R11F_G11F_B10F NaN to the canonical payload 1
+    //     (MG_Util::EncodeFloatToUnsignedSmallFloat) - and a copy-image from RGB9_E5 lands exactly
+    //     such a NaN in the 10-bit blue field every time, because the source's shared-exponent
+    //     field is all ones;
+    //   * the CPU shadow only ever holds what was UPLOADED, so for a level glCopyImageSubData wrote
+    //     it answers with the PRE-COPY contents. MirrorCopyImageIntoDestinationShadow patches that
+    //     up for the shapes it can address texel-exactly and declines for the rest - a renderbuffer
+    //     source (which has no shadow to mirror from at all), a cube or 1D-array endpoint, a
+    //     self-copy - and the decline is silent, so the stale words are served as truth.
+    //
+    // glCopyImageSubData is a raw texel-block move and EXT_copy_image puts every 32-bit colour
+    // format in one compatibility class, so copying the level into a scratch GL_R32UI image and
+    // reading THAT back as unsigned integers hands over the stored words themselves, whoever wrote
+    // them. This is what lets the shadow stop being the authority for these formats: it is tried
+    // first, and every step reports rather than guesses, so a driver that turns any of it down
+    // simply leaves the old shadow/attachment fallbacks to run.
+    static GLuint g_packedWordScratchTextureId = 0;
+    static GLsizei g_packedWordScratchWidth = 0;
+    static GLsizei g_packedWordScratchHeight = 0;
+
+    // Grow-only, so a readback sweep over a mip chain allocates once. Zero when the driver refused
+    // the storage, which is a decline and not an error.
+    static GLuint EnsurePackedWordScratchTexture(GLsizei width, GLsizei height) {
+        if (g_packedWordScratchTextureId != 0 && g_packedWordScratchWidth >= width &&
+            g_packedWordScratchHeight >= height) {
+            return g_packedWordScratchTextureId;
+        }
+        const GLsizei newWidth = std::max(width, g_packedWordScratchWidth);
+        const GLsizei newHeight = std::max(height, g_packedWordScratchHeight);
+        if (g_packedWordScratchTextureId != 0) {
+            // A scratch FBO may still name the old id, and the driver is free to hand the same
+            // number back for the replacement - which would false-skip the re-attach.
+            ScratchFBOImpl::NoteTextureIdDeleted(g_packedWordScratchTextureId);
+            g_GLESFuncs.glDeleteTextures(1, &g_packedWordScratchTextureId);
+            g_packedWordScratchTextureId = 0;
+            g_packedWordScratchWidth = 0;
+            g_packedWordScratchHeight = 0;
+        }
+        GLuint texture = 0;
+        g_GLESFuncs.glGenTextures(1, &texture);
+        if (texture == 0) return 0;
+
+        ClearGLErrors();
+        TextureImpl::ActivateTextureUnit(TextureImpl::TempTextureUnit);
+        g_GLESFuncs.glBindTexture(GL_TEXTURE_2D, texture);
+        // Immutable single-level storage: glCopyImageSubData wants a complete image, and
+        // glTexStorage clamps TEXTURE_MAX_LEVEL, which is what makes a one-level texture complete
+        // under the default mipmapping filter.
+        g_GLESFuncs.glTexStorage2D(GL_TEXTURE_2D, 1, GL_R32UI, newWidth, newHeight);
+        const GLenum storageError = g_GLESFuncs.glGetError();
+        // Re-bind whatever the binding cache says lives on the temp unit, so the cache stays
+        // truthful without a driver query (same discipline as CopyR32FTexture2D).
+        auto* cachedBound = TextureImpl::g_boundTexturesCache[TextureImpl::TempTextureUnit]
+                                                            [static_cast<SizeT>(TextureTarget::Texture2D)];
+        g_GLESFuncs.glBindTexture(GL_TEXTURE_2D, cachedBound ? cachedBound->GetBackendTextureId() : 0);
+        if (storageError != GL_NO_ERROR) {
+            g_GLESFuncs.glDeleteTextures(1, &texture);
+            MGLOG_D("GetTexImage: no %dx%d GL_R32UI scratch image (%s); the verbatim word readback is unavailable",
+                    newWidth, newHeight, MG_Util::ConvertGLEnumToString(storageError).c_str());
+            return 0;
+        }
+        g_packedWordScratchTextureId = texture;
+        g_packedWordScratchWidth = newWidth;
+        g_packedWordScratchHeight = newHeight;
+        return texture;
+    }
+
+    static void ReleasePackedWordScratchTexture() {
+        // The ES context (and the name with it) is gone; deleting here would target a recycled
+        // name in the successor context.
+        g_packedWordScratchTextureId = 0;
+        g_packedWordScratchWidth = 0;
+        g_packedWordScratchHeight = 0;
+    }
+
+    // One slice of `backendTarget`'s level, as width*height stored 32-bit words in `outWords`.
+    static Bool ReadPackedLevelWordsViaScratch(GLuint texture, GLenum backendTarget, GLint level, GLint slice,
+                                               GLsizei width, GLsizei height, Uint32* outWords) {
+        if (texture == 0 || outWords == nullptr || width <= 0 || height <= 0 || level < 0 || slice < 0) return false;
+        if (!g_GLESFuncs.glCopyImageSubData) return false;
+
+        // Horizontal bands, so neither the scratch image nor the staging buffer scales with the
+        // level. The scratch is grow-only on purpose - a sweep down a mip chain must not
+        // reallocate per level - which without a band cap would leave a 4096x4096 readback's
+        // 64 MiB image parked for the rest of the process. The cap is 1 MiB of GL_R32UI, with
+        // 4 MiB of staging behind it because the read lands four words per texel.
+        constexpr SizeT kMaxScratchTexels = SizeT{1} << 18;
+        const GLsizei bandRows = std::max<GLsizei>(
+            1, static_cast<GLsizei>(std::min<SizeT>(kMaxScratchTexels / static_cast<SizeT>(width),
+                                                    static_cast<SizeT>(height))));
+        const GLuint scratch = EnsurePackedWordScratchTexture(width, bandRows);
+        if (scratch == 0) return false;
+
+        ScopedFramebufferBinding readBinding(/*saveRead=*/true, /*saveDraw=*/false);
+        auto& scratchFB = ScratchFBOImpl::BlitReadFramebuffer();
+        FramebufferImpl::BindFramebufferId(GL_READ_FRAMEBUFFER, ScratchFBOImpl::EnsureId(scratchFB));
+        ScratchFBOImpl::EnsureColorAttachment2D(scratchFB, GL_READ_FRAMEBUFFER, scratch, GL_TEXTURE_2D, 0);
+        ScratchFBOImpl::EnsureReadBuffer(scratchFB, GL_COLOR_ATTACHMENT0);
+        if (g_GLESFuncs.glCheckFramebufferStatus(GL_READ_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) {
+            MGLOG_D("GetTexImage: the GL_R32UI scratch attachment is incomplete; falling back");
+            return false;
+        }
+
+        // GL_RGBA_INTEGER/GL_UNSIGNED_INT is the one combination ES guarantees for an integer
+        // colour buffer, so the read lands four words per texel and the red one is compacted out
+        // here. The PACK scope is the tight default rather than the application's, so a row comes
+        // back packed at exactly `width * 4` words. One glGetError covers the whole loop: it
+        // accumulates, and a failure anywhere means the caller falls back rather than trusting a
+        // partial result.
+        const SizeT wordsPerRow = static_cast<SizeT>(width) * 4;
+        Vector<Uint32> staging(static_cast<SizeT>(bandRows) * wordsPerRow);
+        ScopedPixelPackBuffer packBuffer(0);
+        ScopedPackState packState(PixelStoreImpl::PackState{4, 0, 0, 0});
+        ClearGLErrors();
+        for (GLsizei y = 0; y < height; y += bandRows) {
+            const GLsizei rows = std::min(bandRows, height - y);
+            g_GLESFuncs.glCopyImageSubData(texture, backendTarget, level, 0, y, slice, scratch, GL_TEXTURE_2D, 0, 0,
+                                           0, 0, width, rows, 1);
+            g_GLESFuncs.glReadPixels(0, 0, width, rows, GL_RGBA_INTEGER, GL_UNSIGNED_INT, staging.data());
+            for (GLsizei row = 0; row < rows; ++row) {
+                const Uint32* srcRow = staging.data() + static_cast<SizeT>(row) * wordsPerRow;
+                Uint32* dstRow = outWords + static_cast<SizeT>(y + row) * static_cast<SizeT>(width);
+                for (GLsizei x = 0; x < width; ++x) dstRow[x] = srcRow[static_cast<SizeT>(x) * 4];
+            }
+        }
+        const GLenum error = g_GLESFuncs.glGetError();
+        if (error != GL_NO_ERROR) {
+            MGLOG_D("GetTexImage: the GL_R32UI word readback of %s was refused (%s); falling back",
+                    MG_Util::ConvertGLEnumToString(backendTarget).c_str(),
+                    MG_Util::ConvertGLEnumToString(error).c_str());
+            return false;
+        }
+        return true;
+    }
+
     static Bool IsLegacyNativeReadPixelsFormat(GLenum format) {
         return format == GL_RGBA || format == GL_RGBA_INTEGER || format == GL_RED || format == GL_RED_INTEGER ||
                format == GL_DEPTH_COMPONENT || format == GL_STENCIL_INDEX || format == GL_DEPTH_STENCIL;
@@ -7612,9 +8100,14 @@ namespace MobileGL::MG_Backend::DirectGLES {
                 tempFB, GL_READ_FRAMEBUFFER, backendTexId,
                 backendAttachTarget == GL_UNKNOWN_MGL ? target : backendAttachTarget, level,
                 /*withStencil=*/format == GL_DEPTH_STENCIL);
-        } else if (backendAttachTarget == GL_TEXTURE_3D || backendAttachTarget == GL_TEXTURE_2D_ARRAY) {
-            // ES cannot attach 3D/array textures through glFramebufferTexture2D; read layer 0. Reads
-            // of deeper slices are served from the CPU shadow instead (see the shadow-first branch).
+        } else if (backendAttachTarget == GL_TEXTURE_3D || backendAttachTarget == GL_TEXTURE_2D_ARRAY ||
+                   backendAttachTarget == GL_TEXTURE_CUBE_MAP_ARRAY) {
+            // ES cannot attach 3D/array textures through glFramebufferTexture2D; layer 0 here, and
+            // the deeper slices one at a time in the per-layer loop below. A CUBE MAP ARRAY is in
+            // this list for the same reason its layer-faces are addressed as array layers:
+            // glFramebufferTexture2D has no target token for it, so the 2D attach it used to take
+            // left the scratch FBO incomplete and every read fell through to the (stale) CPU
+            // shadow - which is exactly the all-zero result the conformance suite saw.
             ScratchFBOImpl::EnsureColorAttachmentLayer(tempFB, GL_READ_FRAMEBUFFER, backendTexId, level, 0);
         } else {
             ScratchFBOImpl::EnsureColorAttachment2D(
@@ -7667,6 +8160,18 @@ namespace MobileGL::MG_Backend::DirectGLES {
 
         auto size = textureMipmapObject->GetMipmapTexelSize(MG_Util::ConvertGLEnumToTextureUploadTarget(target), level);
 
+        // GL_TEXTURE_1D_ARRAY keeps its LAYERS in the state-side height (that is what
+        // glTexImage2D(GL_TEXTURE_1D_ARRAY, w, layers) means), while the ES texture behind it is a
+        // 2D array of height 1 with the layers in depth - GetBackendUploadSize performs exactly
+        // that swap on the way in. Everything below addresses the ES image, so the same swap has
+        // to happen here: without it the readback asked layer 0 for a `layers`-row rectangle it
+        // does not have, and every layer but the first came back undefined (all zeroes on Adreno,
+        // KHR-GL4x.shader_image_load_store.basic-allTargets-*).
+        const Bool oneDimensionalArray = textureObject->GetTarget() == TextureTarget::Texture1DArray;
+        if (oneDimensionalArray) {
+            size = TextureImpl::GetBackendUploadSize(TextureTarget::Texture1DArray, size);
+        }
+
         MGLOG_D("GetTexImage: mip level %d size = %dx%d", level, size.x(), size.y());
 
         // Prefer the client-format conversion for every convertible combination: the "native" ES pairs
@@ -7680,12 +8185,75 @@ namespace MobileGL::MG_Backend::DirectGLES {
                 TextureImpl::BackendTextureFormatAddsAlpha(textureObject->GetFormat(), textureObject->GetTarget());
             // GL_PACK_IMAGE_HEIGHT/GL_PACK_SKIP_IMAGES only apply to 3D/array image
             // readbacks (cube-map arrays address as arrays); 2D targets must ignore
-            // them (GL 3.3 section 6.1.4).
-            const Bool applyPackImageParams = backendAttachTarget == GL_TEXTURE_3D ||
-                                              backendAttachTarget == GL_TEXTURE_2D_ARRAY ||
-                                              backendAttachTarget == GL_TEXTURE_CUBE_MAP_ARRAY;
+            // them (GL 3.3 section 6.1.4). A 1D ARRAY is one of those 2D targets: GL hands it back
+            // as a single two-dimensional image whose ROWS are the layers, so the layer stride is
+            // one packed row and the image parameters do not enter into it - even though the ES
+            // texture underneath is an array and is read one layer at a time.
+            const Bool applyPackImageParams = !oneDimensionalArray &&
+                                              (backendAttachTarget == GL_TEXTURE_3D ||
+                                               backendAttachTarget == GL_TEXTURE_2D_ARRAY ||
+                                               backendAttachTarget == GL_TEXTURE_CUBE_MAP_ARRAY);
             const GLsizei sliceCount = std::max(size.z(), 1);
             const Bool multiSlice = size.z() > 1;
+            // glGetTexImage answers with the STORED texels, and for a packed format whose encoding
+            // is not unique the GPU route below cannot: it reads GL_RGBA/GL_FLOAT and re-encodes,
+            // which canonicalizes an RGB9_E5 shared exponent (0xf8fc0000 -> 0xe7e00000 - the same
+            // value 8064, different words), and the conformance suite compares the words
+            // ("CopyImageSubData modified contents of source image"). The scratch FBO does NOT
+            // decide this for us: Adreno reports an RGB9_E5 colour attachment complete, so the
+            // shadow branch further down was unreachable. Every other format still prefers the
+            // GPU, so a rendered-into texture is unaffected.
+            const Bool rawPackedWordRead = MG_Util::PixelStoreProcessor::IsRawPackedPixelTransfer(
+                textureObject->GetFormat(), MG_Util::ConvertGLEnumToTextureInputFormat(format),
+                MG_Util::ConvertGLEnumToTexturePixelDataType(type));
+            // ...and the GPU CAN answer with the stored words after all, for any 32-bit packed
+            // format and whoever wrote the level, by going through a scratch GL_R32UI image (see
+            // ReadPackedLevelWordsViaScratch). Preferred over both routes below because it is the
+            // only one that is right for a level glCopyImageSubData wrote: the shadow may never
+            // have seen that write, and re-encoding the attachment cannot reproduce an RGB9_E5
+            // shared exponent or an R11F_G11F_B10F NaN payload. A multisample image is excluded
+            // because copy-image requires matching sample counts.
+            if (rawPackedWordRead && textureObject->GetSamples() == 0) {
+                // Copy-image addresses a cube map as ONE image with the face on z, where
+                // glGetTexImage names the face in its target.
+                const auto readUploadTarget = MG_Util::ConvertGLEnumToTextureUploadTarget(target);
+                const GLint copyBaseSlice =
+                    (readUploadTarget >= TextureUploadTarget::CubeMapPositiveX &&
+                     readUploadTarget <= TextureUploadTarget::CubeMapNegativeZ)
+                        ? static_cast<GLint>(readUploadTarget) -
+                              static_cast<GLint>(TextureUploadTarget::CubeMapPositiveX)
+                        : 0;
+                const GLenum copyTarget =
+                    TextureImpl::ConvertTextureTargetToBackendGLEnum(textureObject->GetTarget());
+                const SizeT sliceWords = static_cast<SizeT>(size.x()) * static_cast<SizeT>(size.y());
+                Vector<Uint32> words(sliceWords * static_cast<SizeT>(sliceCount));
+                Bool allSlicesRead = true;
+                for (GLsizei slice = 0; slice < sliceCount && allSlicesRead; ++slice) {
+                    allSlicesRead = ReadPackedLevelWordsViaScratch(backendTexId, copyTarget, level,
+                                                                   copyBaseSlice + slice, size.x(), size.y(),
+                                                                   words.data() + sliceWords * static_cast<SizeT>(slice));
+                }
+                if (allSlicesRead &&
+                    ReadbackImpl::StorePackedWordsToClient(reinterpret_cast<const Uint8*>(words.data()), size.x(),
+                                                           size.y(), sliceCount, type, pixels,
+                                                           applyPackImageParams)) {
+                    MGLOG_D("GetTexImage: finished %d slice(s) via the bit-exact GL_R32UI word readback", sliceCount);
+                    return;
+                }
+            }
+            // The last resort for the one format the attachment route can never answer for: the
+            // shadow is only right while nothing but a glTexImage has written the level, which is
+            // why CopyImageSubData mirrors itself into it where it can.
+            const Bool verbatimPackedShadowRead =
+                MG_Util::PixelStoreProcessor::HasRedundantPackedEncoding(textureObject->GetFormat()) &&
+                rawPackedWordRead;
+            if (verbatimPackedShadowRead &&
+                GetTexImageViaShadowConversion(textureMipmapObject,
+                                               MG_Util::ConvertGLEnumToTextureUploadTarget(target), level, size.x(),
+                                               size.y(), sliceCount, format, type, pixels, applyPackImageParams)) {
+                MGLOG_D("GetTexImage: finished via shadow conversion (verbatim packed words)");
+                return;
+            }
             // A multi-slice read used to go to the CPU shadow outright, on the grounds that the
             // scratch FBO can only expose one layer at a time. But the shadow only holds what was
             // uploaded, so every slice that was rendered to came back stale - which is exactly what
@@ -7693,7 +8261,8 @@ namespace MobileGL::MG_Backend::DirectGLES {
             // Attach the layers one at a time instead and read each off the GPU, keeping the shadow
             // for the formats the FBO cannot represent at all.
             if (multiSlice && tempFBOComplete &&
-                (backendAttachTarget == GL_TEXTURE_3D || backendAttachTarget == GL_TEXTURE_2D_ARRAY)) {
+                (backendAttachTarget == GL_TEXTURE_3D || backendAttachTarget == GL_TEXTURE_2D_ARRAY ||
+                 backendAttachTarget == GL_TEXTURE_CUBE_MAP_ARRAY)) {
                 // Each slice is packed as its own 2D image, so the per-slice call must not apply
                 // GL_PACK_SKIP_IMAGES / GL_PACK_IMAGE_HEIGHT itself - this walks the destination
                 // over them, using the same layout StoreWideRowsToClient computes.
@@ -8871,6 +9440,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
         XfbImpl::OnBackendContextDestroyed();
         MultiDrawImpl::OnBackendContextDestroyed();
         ScratchFBOImpl::OnBackendContextDestroyed();
+        ReleasePackedWordScratchTexture();
         FramebufferImpl::InvalidateFramebufferBindingCache();
         VertexArrayImpl::InvalidateVAOBindingCache();
         PixelStoreImpl::InvalidatePackStateCache();

MobileGL/MG_Backend/DirectGLES/DirectGLES.h

@@ -76,9 +76,9 @@ namespace MobileGL::MG_Backend::DirectGLES {
                         GLsizei height, GLint border);
     void CopyTexSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width,
                            GLsizei height);
-    void CopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+    void CopyImageSubData(const CopyImageEndpoint& src,
                           GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                          const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                          const CopyImageEndpoint& dst,
                           GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                           GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth);
     void GenerateMipmap(GLenum target);

MobileGL/MG_Backend/DirectGLES/Managers.h

@@ -21,6 +21,16 @@ namespace MobileGL::MG_Backend::DirectGLES {
     String EmulateBaseInstanceInVertexShader(String source, GLenum shaderType);
     String PromoteDrawParameterGlobalsToUniforms(String source, GLenum shaderType);
 
+    // Whether a vertex shader may declare a storage block at all, given what the host driver
+    // reports for GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS. Pure, and separated from the capability
+    // global purely so the decision can be tested without one.
+    //
+    // The indirect half of the gl_BaseInstance lowering in PromoteDrawParameterGlobalsToUniforms
+    // is the only thing that needs this, and it needs exactly one block. A driver reporting 0 is
+    // conformant - the minimum is 0 in GL 4.6 table 23.64 and ES 3.2 table 21.44 - and ARM's
+    // GLES driver does report 0, so this is a live path, not a defensive one.
+    Bool VertexStageStorageBlockUsable(Int maxVertexShaderStorageBlocks);
+
     // True once the process has entered exit(): past that point the EGL library and
     // the driver may already be unloaded, so a backend twin's destructor must not
     // call into g_GLESFuncs (the observed crash is a jump through an unmapped driver
@@ -129,7 +139,28 @@ namespace MobileGL::MG_Backend::DirectGLES {
             // Twin creation is the moment a driver-owned id starts needing a guarded
             // destructor; cold path, so the once-guard costs nothing per draw.
             EnsureProcessTeardownSentinel();
+            // Sweep BEFORE the entry reference below exists: the map is open-addressed and an
+            // erase relocates the rest of the probe cluster, so collecting once that reference
+            // is taken would invalidate it. The sweep is therefore owed from an earlier call
+            // rather than triggered by this one.
+            if (m_creationTick >= kCreationGCInterval) {
+                m_creationTick = 0;
+                CollectGarbage();
+            }
+            const SizeT entryCountBeforeInsert = m_entries.size();
             auto& entry = m_entries[stateObj.get()];
+            if (m_entries.size() != entryCountBeforeInsert) {
+                // A key the registry has never held. Nothing tells the backend that a texture or
+                // renderbuffer was DELETED - the twin, and the driver storage it owns, lives
+                // until a collection - and CollectGarbageIfNeeded is ticked only from the
+                // per-draw sync paths, which a CTS-shaped workload runs about ten times per
+                // case. 1024 of those ticks then span ~100 cases, so ~100 cases' worth of dead
+                // (and, for this suite, gigabyte-sized) objects stay allocated at once. Object
+                // CHURN rather than draw count is what makes the sweep urgent, so a twin the
+                // registry has never seen ticks it too - and it does so on the path that is
+                // about to allocate, which is exactly when the memory is needed.
+                ++m_creationTick;
+            }
             if (entry.stateRef.expired()) {
                 // The previous owner of this address is gone and the allocator handed it
                 // to a new object: its twin describes ids the new state object never made.
@@ -203,8 +234,12 @@ namespace MobileGL::MG_Backend::DirectGLES {
 
     private:
         static constexpr Uint32 kGCInterval = 1024;
+        // Creations are far rarer than draws, so this counts in a much smaller unit than
+        // kGCInterval does.
+        static constexpr Uint32 kCreationGCInterval = 64;
         BackendMap m_entries;
         Uint32 m_gcTick = 0;
+        Uint32 m_creationTick = 0;
         Bool m_isCollecting = false;
     };
 
@@ -361,6 +396,13 @@ namespace MobileGL::MG_Backend::DirectGLES {
         void BindBufferBaseCached(GLenum glTarget, Uint index, Uint id);
         void BindBufferRangeCached(GLenum glTarget, Uint index, Uint id, GLintptr offset, GLsizeiptr size);
         void InvalidateIndexedBufferBindingCache();
+        // Re-issues the GL_ATOMIC_COUNTER_BUFFER binding points a program's shaders declare as
+        // GL_SHADER_STORAGE_BUFFER bindings at the reserved slots the transpiled ESSL was built
+        // against (BackendProgramObjectImpl::GetAtomicCounterBindings /
+        // GetAtomicCounterEsslBindingTop). ES has no counter-buffer target at all, so without
+        // this the shader reads a storage block nobody ever bound a buffer to and the buffer the
+        // application bound never reaches the driver.
+        void SyncAtomicCounterBuffers(const Vector<Int>& glBindings, Int esslBindingTop);
         // Buffer-storage pool maintenance. TrimBufferPool evicts over-budget entries
         // (called once per frame from Present); ClearBufferPool drops all pooled ids
         // without glDeleteBuffers (called when the ES context is going away).
@@ -1051,6 +1093,9 @@ namespace MobileGL::MG_Backend::DirectGLES {
     }
 
     namespace PrgramImpl {
+        // Defined further down, next to CollectImageFormatBakeInputs; only referenced here.
+        struct ImageFormatBakeInputs;
+
         class BackendProgramObjectImpl {
         public:
             // Per-link cache of a sampler-style uniform's backend location: built once in
@@ -1136,6 +1181,13 @@ namespace MobileGL::MG_Backend::DirectGLES {
             // qualifier, so the overrides are baked into the source). A mismatch means the
             // program is stale exactly like the clamp masks above.
             Uint64 GetShaderStorageBlockBindingSignature() const { return m_shaderStorageBlockBindingSignature; }
+            // GL atomic-counter binding points the transpiled stages declare (sorted, unique),
+            // and the top of the reserved shader-storage range their counter blocks were
+            // transpiled against - the slot for GL binding N is `top - N`. Empty for every
+            // program that uses no atomic counter, which is what keeps the per-draw cost of the
+            // counter sync at one empty-vector test.
+            const Vector<Int>& GetAtomicCounterBindings() const { return m_atomicCounterGlBindings; }
+            Int GetAtomicCounterEsslBindingTop() const { return m_atomicCounterEsslBindingTop; }
 
             Bool HasGlobalUboBlock() const { return m_globalUboBackendBlockIndex >= 0; }
             const Vector<Int>& GetUniformBlockBackendIndices() const { return m_uniformBlockBackendIndices; }
@@ -1184,6 +1236,23 @@ namespace MobileGL::MG_Backend::DirectGLES {
         private:
             void CacheResourceLocations(const SharedPtr<MG_State::GLState::ProgramObject>& stateProgramObject);
 
+            // One stage's SPIR-V through the DirectGLES pass chain and SPIRV-Cross, producing
+            // the raw emitted ESSL and the interface blocks this stage's XFB flattening
+            // rewrote. This is the segment the L2 shader-translation memo keys on, so every
+            // input it reads must appear in EsslTranslationKeyInputs - see the definition's
+            // header comment in Managers.cpp and MG_Util/ShaderTranspiler/TranslationCache.h.
+            // False means SPIRV-Cross refused the module; `outError` then carries its message.
+            Bool TranspileSpirvToEssl(const Vector<unsigned int>& spirvCode, GLenum glShaderType,
+                                      const std::set<String>& xfbCaptureBlockNames,
+                                      const ImageFormatBakeInputs& imageFormatBake,
+                                      const UnorderedMap<String, Int>& storageBlockBindingOverrides,
+                                      const std::map<String, String>& inputBlockRenames,
+                                      const std::map<String, String>& outputBlockRenames,
+                                      Int atomicCounterEsslBindingTop, Bool enableSpirvValidation,
+                                      String& outSource,
+                                      std::set<String>& outFlattenedXfbBlockNames,
+                                      Vector<Int>& outAtomicCounterGlBindings, String& outError) const;
+
             Uint m_backendProgramId = 0;
             // GL name of the frontend program this was last synced from; diagnostics only, so
             // an unusable backend program can be traced back to the glCreateProgram id the app
@@ -1202,6 +1271,8 @@ namespace MobileGL::MG_Backend::DirectGLES {
             Uint m_fragColorBroadcastCount = 1;
             // 0 is the signature of an empty override set, i.e. what almost every program has.
             Uint64 m_shaderStorageBlockBindingSignature = 0;
+            Vector<Int> m_atomicCounterGlBindings;
+            Int m_atomicCounterEsslBindingTop = -1;
             Bool m_isInitialized = false;
             Bool m_backendProgramUsable = false;
 

MobileGL/MG_Backend/DirectGLES/Utils.cpp

@@ -171,6 +171,12 @@ namespace MobileGL::MG_Backend::DirectGLES {
             if (!capabilities.SupportsRenderSnorm || !capabilities.SupportsNorm16Texture) {
                 options |= PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget;
             }
+            // 8-bit signed-normalized storage is core ES, so only the rendering half is in
+            // question here; the 16-bit bit above additionally needs EXT_texture_norm16 for the
+            // encoding to exist at all.
+            if (!capabilities.SupportsRenderSnorm) {
+                options |= PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget;
+            }
             return options;
         }
 
@@ -569,6 +575,43 @@ namespace MobileGL::MG_Backend::DirectGLES {
             return glslCode;
         }
 
+        String RequestViewportArrayExtension(String glslCode, Bool needed) {
+#ifdef TRACY_ENABLE
+            ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
+#endif
+            // gl_ViewportIndex is desktop GL 4.1 core and is in ESSL only under
+            // GL_OES_viewport_array. SPIRV-Cross prints the identifier as-is and requests no
+            // extension for it - three lines away from the BuiltInLayer case, which DOES ask for
+            // one on ES - so an untouched decompile reaches the driver naming a builtin its core
+            // language has never heard of. The stage then fails to compile, the program is marked
+            // unusable and every draw made with it renders nothing while raising no GL error.
+            //
+            // Same `needed` contract as RequestExtendedImageFormats, and the same hard rule:
+            // `#extension` on a name the driver does not advertise is itself a compile error
+            // (ARM's compiler is strict about it), so this must never be emitted speculatively.
+            // A driver without the extension does not come through here at all - its module took
+            // the LowerViewportIndexPass fallback and the emitted source no longer names the
+            // builtin.
+            static constexpr const char* kDirective = "#extension GL_OES_viewport_array : require\n";
+            static constexpr const char* kExtName = "GL_OES_viewport_array";
+            if (!needed || glslCode.find(kExtName) != String::npos) {
+                return glslCode;
+            }
+            // Right after the #version line, for the reason spelled out above: it is the only
+            // position that must stay first, and ForceSupporterOutput's scan for the LAST
+            // #extension directive still finds whichever one that ends up being.
+            const SizeT versionPos = glslCode.find("#version");
+            if (versionPos == String::npos) {
+                return kDirective + glslCode;
+            }
+            const SizeT lineEnd = glslCode.find('\n', versionPos);
+            if (lineEnd == String::npos) {
+                return glslCode + "\n" + kDirective;
+            }
+            glslCode.insert(lineEnd + 1, kDirective);
+            return glslCode;
+        }
+
         String BakeImageFormatQualifiers(String glslCode,
                                          const UnorderedMap<String, String>& esslFormatByUniformName) {
 #ifdef TRACY_ENABLE
@@ -785,9 +828,19 @@ namespace MobileGL::MG_Backend::DirectGLES {
             // A rebuilt declaration. Keeps SPIRV-Cross's own word order (`uniform readonly
             // highp image2D`) so the image-rebinding regex in Managers.cpp still matches what
             // comes out of here, whichever order the two passes end up running in.
+            //
+            // `forceCoherent` is for the SPLIT pair only. GLSL guarantees that a write through
+            // one image variable is visible to a read through a DIFFERENT one only when both are
+            // declared coherent, and the split turns a same-variable read-after-write - which
+            // desktop GLSL orders by construction, so the source almost never says `coherent` -
+            // into exactly that cross-variable shape. Without it the driver may serve the load
+            // from a cache that never saw the store through the writeonly half.
             String BuildImageDeclaration(const ImageUniformDecl& decl, const char* memoryQualifier,
-                                         const String& variableName) {
+                                         const String& variableName, Bool forceCoherent = false) {
                 String out = "layout(" + decl.layout + ") uniform ";
+                if (forceCoherent && !ContainsIdentifier(decl.qualifiers, "coherent")) {
+                    out += "coherent ";
+                }
                 out += memoryQualifier;
                 out += ' ';
                 if (!decl.qualifiers.empty()) {
@@ -971,9 +1024,15 @@ namespace MobileGL::MG_Backend::DirectGLES {
                     decl.writeName = MakeImageWriteAliasName(decl.name, glslCode, takenAliases);
                     takenAliases.push_back(decl.writeName);
                     decl.split = true;
+                    // Both halves carry `coherent`; see BuildImageDeclaration. The
+                    // single-declaration cases below stay as they were - nothing aliases them, so
+                    // there is no visibility to restore and no reason to pay for the cache
+                    // behaviour.
                     edits.push_back({decl.declStart, decl.declLength,
-                                     BuildImageDeclaration(decl, "readonly", decl.name) + "\n" +
-                                         BuildImageDeclaration(decl, "writeonly", decl.writeName)});
+                                     BuildImageDeclaration(decl, "readonly", decl.name, /*forceCoherent=*/true) +
+                                         "\n" +
+                                         BuildImageDeclaration(decl, "writeonly", decl.writeName,
+                                                               /*forceCoherent=*/true)});
                 } else if (decl.stored) {
                     edits.push_back({decl.declStart, decl.declLength,
                                      BuildImageDeclaration(decl, "writeonly", decl.name)});

MobileGL/MG_Backend/DirectGLES/Utils.h

@@ -154,6 +154,16 @@ namespace MobileGL::MG_Backend::DirectGLES {
         // extension - requesting an unadvertised extension is itself a compile error, so this is
         // never emitted speculatively. A no-op when not needed or already present.
         String RequestExtendedImageFormats(String glslCode, Bool needed);
+        // Adds `#extension GL_OES_viewport_array : require` when the emitted ESSL names
+        // gl_ViewportIndex. SPIRV-Cross prints that identifier and asks for nothing (unlike
+        // gl_Layer, which it backs with GL_NV_viewport_array2 on ES) and ESSL has no core
+        // spelling for it at any version, so the request has to be made here or the stage does
+        // not compile - which loses the whole program, not just the multi-viewport routing.
+        // `needed` is the caller's answer for the same reason as above: only it knows whether the
+        // driver advertises the extension, and requesting an unadvertised one is itself a compile
+        // error, so this is never emitted speculatively. A no-op when not needed or already
+        // present.
+        String RequestViewportArrayExtension(String glslCode, Bool needed);
         // Writes a format layout qualifier into the image declarations named in
         // `esslFormatByUniformName` that still have none. The completion half of the image-format
         // bake, and ONLY that: the SPIR-V pass (BakeImageFormatsPass) is what normally puts the
@@ -186,11 +196,18 @@ namespace MobileGL::MG_Backend::DirectGLES {
         //  * loaded only            -> add `readonly`
         //  * stored only            -> add `writeonly`
         //  * both                   -> emit TWO declarations on the same binding and of the
-        //                              same type, `readonly <name>` and `writeonly
-        //                              <IMAGE_WRITE_ALIAS_PREFIX><name>`, and point every
-        //                              imageStore at the second one. Several image variables
-        //                              may share an image unit as long as they have the same
-        //                              type and format, which is exactly what the pair is.
+        //                              same type, `coherent readonly <name>` and `coherent
+        //                              writeonly <IMAGE_WRITE_ALIAS_PREFIX><name>`, and point
+        //                              every imageStore at the second one. Several image
+        //                              variables may share an image unit as long as they have
+        //                              the same type and format, which is exactly what the pair
+        //                              is.
+        //
+        // The `coherent` on both halves of the pair is load-bearing, not decoration: GLSL only
+        // guarantees a write through one image variable is visible to a read through a DIFFERENT
+        // one when both are coherent, and the split is what makes a same-variable
+        // read-after-write cross-variable. The single-declaration repairs above do not get it -
+        // nothing aliases them.
         //
         // Budget note: the split DOUBLES the image-uniform count of the stage it fires in, so
         // a driver advertising a tight GL_MAX_{FRAGMENT,VERTEX,...}_IMAGE_UNIFORMS can turn a

MobileGL/MG_Backend/DirectVulkan/BackendObject_DirectVulkan.cpp

@@ -847,6 +847,38 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         m_dynamicParameters.MaxShaderStorageBufferBindings =
             clampLimit("GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS", m_vulkanCaps.MaxShaderStorageBufferBindings,
                        kMaxAdvertisedBufferBlocks);
+        // Per-stage GL_MAX_*_SHADER_STORAGE_BLOCKS. Vulkan has one descriptor limit for every
+        // stage (maxPerStageDescriptorStorageBuffers, which is what MaxComputeShaderStorageBlocks
+        // carries), so the stage limits differ only by whether the stage can have blocks at all.
+        //
+        // Deliberately NOT gated on vertexPipelineStoresAndAtomics, unlike the per-stage image
+        // uniforms below. That gate reads as the obvious one and is wrong here in practice: a
+        // Mali-G925-Immortalis reports vertexPipelineStoresAndAtomics=false (supported AND
+        // enabled) and yet runs all 433 KHR-GL43.constant_expressions.*_tess_* cases correctly
+        // through this backend - those write their result through a storage block declared in a
+        // tessellation stage. Gating would report 0 and turn 433 passing cases into
+        // "unsupported", removing function that demonstrably works.
+        //
+        // The asymmetry with DirectGLES is real and is the point. There, 0 prevents a program
+        // the driver refuses outright at link time; the honest limit converts a silent
+        // wrong-render into a capability an application can route around. Here there is no such
+        // failure to prevent, so the limit stays at what the device can address. If a Vulkan
+        // device is ever found that genuinely rejects such a pipeline, the gate belongs at
+        // pipeline creation where the rejection is observable, not on a feature bit this driver
+        // reports inaccurately.
+        {
+            const Int maxPerStageStorageBlocks =
+                std::min(std::max(m_dynamicParameters.MaxComputeShaderStorageBlocks, 0),
+                         std::min(std::max(m_dynamicParameters.MaxCombinedShaderStorageBlocks, 0),
+                                  std::max(m_dynamicParameters.MaxShaderStorageBufferBindings, 0)));
+            m_dynamicParameters.MaxVertexShaderStorageBlocks = maxPerStageStorageBlocks;
+            m_dynamicParameters.MaxTessControlShaderStorageBlocks = maxPerStageStorageBlocks;
+            m_dynamicParameters.MaxTessEvaluationShaderStorageBlocks = maxPerStageStorageBlocks;
+            // The one hard capability in the set: no geometry stage means no blocks in it.
+            m_dynamicParameters.MaxGeometryShaderStorageBlocks =
+                m_vulkanCaps.SupportsGeometryShader ? maxPerStageStorageBlocks : 0;
+            m_dynamicParameters.MaxFragmentShaderStorageBlocks = maxPerStageStorageBlocks;
+        }
         m_dynamicParameters.MaxTextureBufferSize = clampLimit(
             "GL_MAX_TEXTURE_BUFFER_SIZE", m_vulkanCaps.MaxTextureBufferSize, kMaxAdvertisedTextureBufferSize);
         m_dynamicParameters.TextureBufferOffsetAlignment = m_vulkanCaps.TextureBufferOffsetAlignment;
@@ -873,8 +905,22 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         const Int maxSupportedDrawBuffers = static_cast<Int>(MG_State::GLState::FramebufferObject::MAX_DRAW_BUFFERS);
         m_dynamicParameters.MaxDrawBuffers = std::min(m_vulkanCaps.MaxDrawBuffers, maxSupportedDrawBuffers);
         m_dynamicParameters.MaxColorAttachments = std::min(m_vulkanCaps.MaxColorAttachments, maxSupportedDrawBuffers);
-        m_dynamicParameters.MaxClipDistances = m_vulkanCaps.MaxClipDistances;
+        // Same shape as the image-uniform limits three lines above: maxClipDistances is reported
+        // by every device, but declaring ClipDistance in a module needs the shaderClipDistance
+        // FEATURE, which VulkanRenderer enables exactly where the physical device has it. Without
+        // it the limit describes a capacity no shader may use, so report none.
+        m_dynamicParameters.MaxClipDistances =
+            m_vulkanCaps.SupportsShaderClipDistance ? std::max(m_vulkanCaps.MaxClipDistances, 0) : 0;
         m_dynamicParameters.MaxViewports = m_vulkanCaps.MaxViewports;
+        // Assigned explicitly rather than left to the struct's defaults, like every other
+        // parameter here, so a second fill cannot inherit a stale value. GL_UNDEFINED_VERTEX is
+        // the truthful answer for DirectVulkan and a legal one (GL 4.6 table 23.65): which vertex
+        // provokes is chosen per pipeline by VulkanRenderer::SelectProvokingVertexMode out of
+        // VK_EXT_provoking_vertex, provokingVertexModePerPipeline and the topology, so there is no
+        // one convention to name. Vulkan's own default is FIRST, which is the opposite of the
+        // GL_LAST_VERTEX_CONVENTION this used to claim unconditionally.
+        m_dynamicParameters.LayerProvokingVertex = GL_UNDEFINED_VERTEX;
+        m_dynamicParameters.ViewportIndexProvokingVertex = GL_UNDEFINED_VERTEX;
         m_dynamicParameters.MaxViewportWidth = m_vulkanCaps.MaxViewportWidth;
         m_dynamicParameters.MaxViewportHeight = m_vulkanCaps.MaxViewportHeight;
         m_dynamicParameters.ViewportBoundsRangeMin = m_vulkanCaps.ViewportBoundsRangeMin;

MobileGL/MG_Backend/DirectVulkan/DirectVulkan.cpp

@@ -632,15 +632,15 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         MOBILEGL_ASSERT(MG_State::pGLContext, "DirectVulkan::CopyTexSubImage2D called with null GL context");
         pVulkanRenderer->CopyTexSubImage2D(target, level, xoffset, yoffset, x, y, width, height);
     }
-    void CopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+    void CopyImageSubData(const CopyImageEndpoint& src,
                           GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                          const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                          const CopyImageEndpoint& dst,
                           GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                           GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
         MOBILEGL_ASSERT(pVulkanRenderer, "DirectVulkan::CopyImageSubData called with null VulkanRenderer");
         MOBILEGL_ASSERT(MG_State::pGLContext, "DirectVulkan::CopyImageSubData called with null GL context");
-        pVulkanRenderer->CopyImageSubData(srcTexture, srcTarget, srcLevel, srcX, srcY, srcZ,
-                                          dstTexture, dstTarget, dstLevel, dstX, dstY, dstZ,
+        pVulkanRenderer->CopyImageSubData(src, srcTarget, srcLevel, srcX, srcY, srcZ,
+                                          dst, dstTarget, dstLevel, dstX, dstY, dstZ,
                                           srcWidth, srcHeight, srcDepth);
     }
     void GenerateMipmap(GLenum target) {

MobileGL/MG_Backend/DirectVulkan/DirectVulkan.h

@@ -82,9 +82,9 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                         GLsizei height, GLint border);
     void CopyTexSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint x, GLint y, GLsizei width,
                            GLsizei height);
-    void CopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+    void CopyImageSubData(const CopyImageEndpoint& src,
                           GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                          const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                          const CopyImageEndpoint& dst,
                           GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                           GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth);
     void GenerateMipmap(GLenum target);

MobileGL/MG_Backend/DirectVulkan/Renderer/VertexInputStateFactory.cpp

@@ -8,6 +8,7 @@
 
 #include "VertexInputStateFactory.h"
 #include "MG_Util/Converters/MGToStr/DataTypeConverter.h"
+#include <MG_Backend/BackendObjects.h>
 #include <utility>
 
 namespace MobileGL::MG_Backend::DirectVulkan {
@@ -330,6 +331,20 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             // for every R64 float format, so a native 64-bit vertex fetch is simply unavailable there
             // while shaderFloat64 is not. Both halves key off nothing but the attribute being long,
             // so they always agree without extra plumbing.
+            //
+            // ... as long as the shader half still runs. It does not when the backend has declared
+            // no 64-bit vertex attribute support: DemoteFloat64Pass has already narrowed every
+            // `dvec` input to a `vec` by then, so PackDoubleVertexInputsPass finds nothing to pack
+            // and a UINT-formatted attribute would be fed to a float input - garbage with no
+            // diagnostic anywhere. Declining here drops the array instead (the caller skips
+            // UNDEFINED attributes and reports them through unsupportedAttribMask), which is what
+            // DirectGLES does for the same state. The frontend RECORDS the format either way, so
+            // this gate is the only thing standing between a legal glVertexAttribLFormat and a
+            // mismatched pipeline.
+            if (MG_Backend::pActiveBackendObject == nullptr ||
+                !MG_Backend::pActiveBackendObject->GetDynamicParameters().SupportsFloat64VertexAttributes) {
+                return VK_FORMAT_UNDEFINED;
+            }
             if (!isLong || isInteger || normalized) return VK_FORMAT_UNDEFINED;
             switch (size) {
             case 1: return VK_FORMAT_R32G32_UINT;

MobileGL/MG_Backend/DirectVulkan/Renderer/VkTextureManager.cpp

@@ -1494,6 +1494,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         const auto* mipTexture = MG_State::GLState::AsMipmapTexture(&texture);
         const Uint32 mipLevelCount = mipTexture != nullptr ? mipTexture->GetMipmapLevelCount() : 0u;
         return resource.syncedContentVersion != texture.GetContentVersion() ||
+               resource.syncedShapeVersion != texture.GetShapeVersion() ||
                resource.syncedTextureParamsVersion != texture.GetTextureParamsVersion() ||
                resource.syncedMipLevelCount != mipLevelCount;
     }
@@ -1593,11 +1594,16 @@ namespace MobileGL::MG_Backend::DirectVulkan {
     Bool VkTextureManager::SyncTexture(MG_State::GLState::ITextureObject &texture,
                                        TextureResource &outResource) {
         // Cross-draw fast path: if the resource is already built and neither the texture's
-        // pixel content (bumped in MarkStorageDirty) nor its params changed since the last
-        // sync, there is nothing to re-check or re-upload - skip CheckMipmapCompleteness,
-        // SyncTextureResource, SyncTextureViews and the per-level dirty scan. Layout is
-        // maintained separately by the transition path, so the resource still reflects truth.
+        // pixel content (bumped in MarkStorageDirty), its SHAPE (bumped in BumpShapeVersion)
+        // nor its params changed since the last sync, there is nothing to re-check or
+        // re-upload - skip CheckMipmapCompleteness, SyncTextureResource, SyncTextureViews and
+        // the per-level dirty scan. Layout is maintained separately by the transition path, so
+        // the resource still reflects truth. The shape version is NOT redundant with the
+        // content one: glTexImage2D(..., nullptr) re-specifies a level's size or format
+        // without dirtying a texel, which is exactly how a re-specified image-unit texture used
+        // to keep reporting its old imageSize().
         const Uint64 syncingContentVersion = texture.GetContentVersion();
+        const Uint64 syncingShapeVersion = texture.GetShapeVersion();
         const auto* syncingMipTexture = MG_State::GLState::AsMipmapTexture(&texture);
         const Uint32 syncingMipLevelCount =
             syncingMipTexture != nullptr ? syncingMipTexture->GetMipmapLevelCount() : 0u;
@@ -1609,6 +1615,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             m_storageImageTextures.find(MakeTextureIdentity(&texture)) != m_storageImageTextures.end();
         if (outResource.image != VK_NULL_HANDLE && !storageUpgradePending &&
             outResource.syncedContentVersion == syncingContentVersion &&
+            outResource.syncedShapeVersion == syncingShapeVersion &&
             outResource.syncedTextureParamsVersion == texture.GetTextureParamsVersion() &&
             outResource.syncedMipLevelCount == syncingMipLevelCount) {
             return true;
@@ -1629,6 +1636,12 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             return false;
         }
 
+        // From here down the size is VULKAN geometry, not GL's: a 1D array's layer count moves
+        // out of the height it occupies GL-side and into z, which is the slot
+        // TryResolveTextureShapeInfo reads arrayLayers from and the only one that leaves
+        // extent.height at the 1 a VK_IMAGE_TYPE_1D image is required to have.
+        texelSize = ToVulkanLevelExtent(texture.GetTarget(), texelSize);
+
         if (!SyncTextureResource(texture, uploadTarget, texelSize, byteSize, mipLevelCount, outResource)) {
             MGLOG_D("%s: SyncTextureResource failed", __func__);
             return false;
@@ -1660,6 +1673,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         if (!hasDirtyMipLevel) {
             outResource.syncedContentVersion = syncingContentVersion;
             outResource.syncedMipLevelCount = syncingMipLevelCount;
+            outResource.syncedShapeVersion = syncingShapeVersion;
             return true;
         }
 
@@ -1669,6 +1683,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         }
         outResource.syncedContentVersion = syncingContentVersion;
         outResource.syncedMipLevelCount = syncingMipLevelCount;
+        outResource.syncedShapeVersion = syncingShapeVersion;
         return true;
     }
 
@@ -1848,6 +1863,19 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                         }
                     }
                 }
+                if (rounded == 0 && (supported & VK_SAMPLE_COUNT_1_BIT) != 0) {
+                    // Nothing at two samples or above. Reachable because the frontend validates
+                    // multisample allocations against the count MobileGL ADVERTISES (GL requires
+                    // GL_MAX_SAMPLES >= 4) rather than against the device's per-format support, so
+                    // a format this device cannot multisample at all now gets here instead of
+                    // being refused up front. Keeping the unsupported count would hand
+                    // vkCreateImage an invalid VkImageCreateInfo; one sample is at least a legal
+                    // image, and the samples-08726 hazard above is the lesser of the two.
+                    MGLOG_W_ONCE("Multisample texture format %d supports no count above one on this device; "
+                                 "backing it with a single sample",
+                                 static_cast<Int>(format));
+                    rounded = static_cast<Uint32>(VK_SAMPLE_COUNT_1_BIT);
+                }
                 if (rounded != 0) {
                     resolvedSampleCount = static_cast<VkSampleCountFlagBits>(rounded);
                 }
@@ -2523,7 +2551,13 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                 uploadItem.target = target;
                 uploadItem.level = level;
                 uploadItem.baseArrayLayer = ResolveUploadArrayLayer(target);
-                uploadItem.texelSize = texelSize;
+                // Vulkan geometry, like the image this stages into (see SyncTexture): a 1D
+                // array's layers move from y to z, where the copy loop's depthSelectsArrayLayer
+                // branch turns them into layerCount. The shadow needs no repacking to follow -
+                // one layer of a 1D array IS one row of `width` texels, so the tight-packed
+                // per-layer copy the swapped size describes reads the same bytes in the same
+                // order as the row-major level it replaces.
+                uploadItem.texelSize = ToVulkanLevelExtent(mipmapTexture.GetTarget(), texelSize);
                 uploadItem.source = source;
                 uploadItem.offset = stagingSize;
                 uploadItem.uploadByteSize = byteSize;
@@ -2561,6 +2595,23 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                             }
                             uploadItem.uploadByteSize = rectTexels * uploadItem.texelBytes;
                         }
+                        // The boxes came out of the shadow in GL coordinates, where a 1D
+                        // array's layer is the y. They have to follow texelSize across to z or
+                        // they would address rows of an image that now has exactly one, and
+                        // the staging walk would read the wrong bytes for them. Every byte
+                        // count computed above is a product of the three extents, so moving
+                        // the axes leaves all of them alone - and an OFFSET lands on a zero y,
+                        // not on the extent's one, which is why this is spelled out rather than
+                        // handed to ToVulkanLevelExtent.
+                        if (mipmapTexture.GetTarget() == TextureTarget::Texture1DArray) {
+                            uploadItem.regionLo = {uploadItem.regionLo.x(), 0, uploadItem.regionLo.y()};
+                            uploadItem.regionSize = {uploadItem.regionSize.x(), 1,
+                                                     uploadItem.regionSize.y()};
+                            for (auto& rect : uploadItem.rects) {
+                                rect.lo = {rect.lo.x(), 0, rect.lo.y()};
+                                rect.hi = {rect.hi.x(), 1, rect.hi.y()};
+                            }
+                        }
                     }
                 }
                 if (formatInfo.expandRgbToRgba) {

MobileGL/MG_Backend/DirectVulkan/Renderer/VkTextureManager.h

@@ -22,6 +22,25 @@ class ITextureObject;
 namespace MobileGL::MG_Backend::DirectVulkan {
 enum class SamplerNumericDomain : Uint8;
 
+// A GL 1D-ARRAY level keeps its LAYER COUNT in the state-side HEIGHT: that is what
+// glTexImage2D(GL_TEXTURE_1D_ARRAY, width, layers) means, and the frontend records the level
+// as {width, layers, 1} (see GL_Texture.cpp's AllocateStorage and the completeness walk in
+// TextureObject.cpp, which shrinks only x down the chain). Vulkan packs it the other way: a
+// 1D array is a VK_IMAGE_TYPE_1D image whose extent.height MUST be 1 and whose layers live in
+// arrayLayers - i.e. in the slot this backend reads out of z. So every place that turns a GL
+// level size into Vulkan image geometry has to move the count across first, and every GL-space
+// sub-box that rides along with it has to move its y the same way. DirectGLES performs the
+// identical remap onto the ES 2D array it maps 1D arrays to (GetBackendUploadSize).
+//
+// Applied to nothing else: a 2D array, a cube array and a 3D texture all already carry their
+// depth/layer count in z, which is where the Vulkan side expects it.
+inline IntVec3 ToVulkanLevelExtent(TextureTarget stateTarget, const IntVec3& glTexelSize) {
+    if (stateTarget == TextureTarget::Texture1DArray) {
+        return {glTexelSize.x(), 1, glTexelSize.y()};
+    }
+    return glTexelSize;
+}
+
 class VkTextureManager {
 public:
     // Monotonic epoch bumped whenever a texture VkImage is (re)created. The render-pass
@@ -206,6 +225,12 @@ public:
         // as defense-in-depth: any path that grows the level set (which resizes the sampled view)
         // busts the skip even if it failed to bump the content version.
         Uint32 syncedMipLevelCount = 0;
+        // Snapshot of ITextureObject::GetShapeVersion() at the last successful sync. The content
+        // version alone does NOT cover a re-specification: glTexImage2D(..., nullptr) on an
+        // already-defined level changes its size or format and dirties no texel, so it moves the
+        // shape version and nothing else. Without this in the early-out key the image, its views
+        // and therefore imageSize() all keep answering with the texture's PREVIOUS shape.
+        Uint64 syncedShapeVersion = 0;
 
         TextureResource() = default;
         TextureResource(const TextureResource&) = delete;
@@ -237,6 +262,7 @@ public:
             std::swap(this->lastRecordingGeneration, that.lastRecordingGeneration);
             std::swap(this->syncedContentVersion, that.syncedContentVersion);
             std::swap(this->syncedMipLevelCount, that.syncedMipLevelCount);
+            std::swap(this->syncedShapeVersion, that.syncedShapeVersion);
         }
 
         void Reset() {
@@ -300,6 +326,7 @@ public:
             syncedTextureParamsVersion = 0;
             syncedContentVersion = 0;
             syncedMipLevelCount = 0;
+            syncedShapeVersion = 0;
         }
 
         ~TextureResource() {

MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRenderer.cpp

@@ -8869,7 +8869,7 @@ void main() {
         // A mixed 2D-array <-> 3D pair is legal because maintenance1 - core since Vulkan 1.1 -
         // relaxed the old "layerCounts must match" rule into "the 3D side's extent.depth must
         // equal the array side's layerCount".
-        struct CopyImageEndpoint {
+        struct CopyImageSliceMapping {
             // True for a VK_IMAGE_TYPE_3D image, i.e. slices ride the z axis, not the layer axis.
             Bool slicesAreDepth = false;
             // The GL z offset, kept in whichever field this endpoint's image type reads it from.
@@ -8883,13 +8883,35 @@ void main() {
             Int32 OffsetZ() const { return slicesAreDepth ? static_cast<Int32>(baseSlice) : 0; }
         };
 
-        Bool TryResolveCopyImageEndpoint(TextureTarget target,
-                                         const VkTextureManager::TextureResource& resource, Uint32 mipLevel,
-                                         GLint glZ, GLsizei glDepth, CopyImageEndpoint& outEndpoint) {
+        // The Vulkan image one glCopyImageSubData endpoint names, after the two object kinds GL
+        // 4.6 core 18.3.2 allows have been collapsed onto the fields this copy reads. A
+        // renderbuffer is a single-level, single-layer 2D image, so its shape answers are
+        // constants rather than a mip walk. `trackedLayout` points AT the owning resource's own
+        // layout field - both resource maps are node-based, so the pointer survives the further
+        // lookups the clear materialization below makes.
+        struct CopyImageVkImage {
+            Bool isRenderbuffer = false;
+            VkImage image = VK_NULL_HANDLE;
+            VkImageLayout* trackedLayout = nullptr;
+            VkImageAspectFlags aspect = VK_IMAGE_ASPECT_NONE;
+            Uint32 mipLevels = 1;
+            VkExtent2D extent = {0, 0};
+            Uint32 depth = 1;
+            Uint32 arrayLayers = 1;
+        };
+
+        Bool TryResolveCopyImageSliceMapping(TextureTarget target, const CopyImageVkImage& image, Uint32 mipLevel,
+                                             GLint glZ, GLsizei glDepth, CopyImageSliceMapping& outMapping) {
             if (glZ < 0 || glDepth <= 0) {
                 return false;
             }
             const Uint32 baseSlice = static_cast<Uint32>(glZ);
+            if (image.isRenderbuffer) {
+                // A renderbuffer holds one 2D image and nothing else; GL still requires the
+                // z/depth pair and it can only name that one slice.
+                outMapping = {};
+                return baseSlice == 0 && glDepth == 1;
+            }
             switch (target) {
             case TextureTarget::Texture1D:
             case TextureTarget::Texture2D:
@@ -8897,12 +8919,12 @@ void main() {
             case TextureTarget::Texture2DMultisample:
                 // Not layered at all: GL still requires the z/depth pair, and it can only name the
                 // one slice these targets have.
-                outEndpoint = {};
+                outMapping = {};
                 return baseSlice == 0 && glDepth == 1;
             case TextureTarget::Texture3D:
-                outEndpoint.slicesAreDepth = true;
-                outEndpoint.baseSlice = baseSlice;
-                outEndpoint.availableSlices = std::max(1u, resource.depth >> mipLevel);
+                outMapping.slicesAreDepth = true;
+                outMapping.baseSlice = baseSlice;
+                outMapping.availableSlices = std::max(1u, image.depth >> mipLevel);
                 return true;
             case TextureTarget::Texture2DArray:
             case TextureTarget::Texture2DMultisampleArray:
@@ -8911,9 +8933,9 @@ void main() {
                 // A cube map is an array of six faces here (see TryResolveTextureShapeInfo), and GL
                 // numbers its faces on the same z axis an array texture numbers its layers, so both
                 // arrive as a plain layer range.
-                outEndpoint.slicesAreDepth = false;
-                outEndpoint.baseSlice = baseSlice;
-                outEndpoint.availableSlices = resource.arrayLayers;
+                outMapping.slicesAreDepth = false;
+                outMapping.baseSlice = baseSlice;
+                outMapping.availableSlices = image.arrayLayers;
                 return true;
             default:
                 // GL_TEXTURE_1D_ARRAY carries its layers on the Y axis (srcY/srcHeight), which
@@ -8923,15 +8945,20 @@ void main() {
                 return false;
             }
         }
+
+        Uint CopyImageEndpointName(const CopyImageEndpoint& endpoint) {
+            if (endpoint.IsRenderbuffer()) return endpoint.Renderbuffer->GetExternalIndex();
+            return endpoint.Texture ? endpoint.Texture->GetExternalIndex() : 0u;
+        }
     } // namespace
 
-    void VulkanRenderer::CopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+    void VulkanRenderer::CopyImageSubData(const CopyImageEndpoint& srcEndpoint,
                                           GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                                          const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                                          const CopyImageEndpoint& dstEndpoint,
                                           GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                                           GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
-        MOBILEGL_ASSERT(srcTexture != nullptr && dstTexture != nullptr,
-                        "CopyImageSubData requires valid source and destination textures.");
+        MOBILEGL_ASSERT(srcEndpoint.Exists() && dstEndpoint.Exists(),
+                        "CopyImageSubData requires valid source and destination images.");
         // The frontend already declines a zero or negative extent, so anything else here is a
         // caller MobileGL wrote - but it still reaches vkCmdCopyImage in a release build, and a
         // zero extent.depth is as invalid as a zero width.
@@ -8948,9 +8975,9 @@ void main() {
         // and an overlap check). Refused outright, and refused for real rather than through an
         // assertion the release build drops: recording the pair anyway is a validation error and,
         // on a tiler, a copy whose source has already been overwritten.
-        if (srcTexture.get() == dstTexture.get()) {
-            MGLOG_E_ONCE("%s: in-place copy on textureId=%d is not supported; declining the copy", __func__,
-                         srcTexture->GetExternalIndex());
+        if (srcEndpoint.Texture == dstEndpoint.Texture && srcEndpoint.Renderbuffer == dstEndpoint.Renderbuffer) {
+            MGLOG_E_ONCE("%s: in-place copy on objectId=%u is not supported; declining the copy", __func__,
+                         CopyImageEndpointName(srcEndpoint));
             return;
         }
 
@@ -8963,8 +8990,42 @@ void main() {
             VkRenderPassManager::EndRenderPass(frame.commandBuffer);
         }
 
-        auto* srcResource = m_textureManager->SyncTextureAndGetDescriptor(*srcTexture);
-        auto* dstResource = m_textureManager->SyncTextureAndGetDescriptor(*dstTexture);
+        // One resolver for both object kinds. The texture arm is the same
+        // SyncTextureAndGetDescriptor the copy always used; the renderbuffer arm goes through the
+        // render-pass manager, which is where a renderbuffer's VkImage lives.
+        const auto resolveImage = [this](const CopyImageEndpoint& endpoint, CopyImageVkImage& out) {
+            if (endpoint.IsRenderbuffer()) {
+                auto* resource = m_renderPassManager->GetOrCreateRenderbufferResource(endpoint.Renderbuffer);
+                if (resource == nullptr) return false;
+                out.isRenderbuffer = true;
+                out.image = resource->image;
+                out.trackedLayout = &resource->layout;
+                out.aspect = resource->aspect;
+                out.mipLevels = 1;
+                out.extent = resource->extent;
+                out.depth = 1;
+                out.arrayLayers = 1;
+                return out.image != VK_NULL_HANDLE;
+            }
+            // An endpoint that named nothing is the frontend validator's INVALID_VALUE and never
+            // reaches here - but the assertion that says so is compiled out of a release build.
+            if (endpoint.Texture == nullptr) return false;
+            auto* resource = m_textureManager->SyncTextureAndGetDescriptor(*endpoint.Texture);
+            if (resource == nullptr) return false;
+            out.isRenderbuffer = false;
+            out.image = resource->image;
+            out.trackedLayout = &resource->layout;
+            out.aspect = resource->aspect;
+            out.mipLevels = resource->mipLevels;
+            out.extent = resource->extent;
+            out.depth = resource->depth;
+            out.arrayLayers = resource->arrayLayers;
+            return true;
+        };
+        CopyImageVkImage srcImage{};
+        CopyImageVkImage dstImage{};
+        const Bool srcResolved = resolveImage(srcEndpoint, srcImage);
+        const Bool dstResolved = resolveImage(dstEndpoint, dstImage);
         // Real checks, not MOBILEGL_ASSERT: the assertions this replaces compile to nothing in
         // a release build, which is where both observed failures happened - a null resource
         // dereferenced right below (lavapipe) and a mip level the VkImage does not have handed
@@ -8980,29 +9041,29 @@ void main() {
         // The frontend validator (ValidateTextureLevelExists) is what produces the
         // GL_INVALID_VALUE the application is actually owed. This guard exists so the next gap
         // up there declines a copy instead of taking the process down.
-        if (srcResource == nullptr || dstResource == nullptr) {
-            MGLOG_E_ONCE("%s: source or destination texture failed to sync; declining the copy", __func__);
+        if (!srcResolved || !dstResolved) {
+            MGLOG_E_ONCE("%s: source or destination image failed to sync; declining the copy", __func__);
             return;
         }
-        if (srcLevel < 0 || dstLevel < 0 || static_cast<Uint32>(srcLevel) >= srcResource->mipLevels ||
-            static_cast<Uint32>(dstLevel) >= dstResource->mipLevels) {
+        if (srcLevel < 0 || dstLevel < 0 || static_cast<Uint32>(srcLevel) >= srcImage.mipLevels ||
+            static_cast<Uint32>(dstLevel) >= dstImage.mipLevels) {
             MGLOG_E_ONCE("%s: mip level out of range (src %d of %u, dst %d of %u); declining the copy", __func__,
-                         srcLevel, srcResource->mipLevels, dstLevel, dstResource->mipLevels);
+                         srcLevel, srcImage.mipLevels, dstLevel, dstImage.mipLevels);
             return;
         }
         const VkImageAspectFlags copyAspectMask =
-            srcResource->aspect & dstResource->aspect &
+            srcImage.aspect & dstImage.aspect &
             (VK_IMAGE_ASPECT_COLOR_BIT | VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT);
         MOBILEGL_ASSERT(copyAspectMask != 0 &&
-                        (srcResource->aspect & copyAspectMask) == srcResource->aspect &&
-                        (dstResource->aspect & copyAspectMask) == dstResource->aspect,
+                        (srcImage.aspect & copyAspectMask) == srcImage.aspect &&
+                        (dstImage.aspect & copyAspectMask) == dstImage.aspect,
                         "CopyImageSubData source and destination aspects are incompatible.");
         const Uint32 srcMipLevel = static_cast<Uint32>(srcLevel);
         const Uint32 dstMipLevel = static_cast<Uint32>(dstLevel);
-        const Uint32 srcMipWidth = std::max(1u, srcResource->extent.width >> srcMipLevel);
-        const Uint32 srcMipHeight = std::max(1u, srcResource->extent.height >> srcMipLevel);
-        const Uint32 dstMipWidth = std::max(1u, dstResource->extent.width >> dstMipLevel);
-        const Uint32 dstMipHeight = std::max(1u, dstResource->extent.height >> dstMipLevel);
+        const Uint32 srcMipWidth = std::max(1u, srcImage.extent.width >> srcMipLevel);
+        const Uint32 srcMipHeight = std::max(1u, srcImage.extent.height >> srcMipLevel);
+        const Uint32 dstMipWidth = std::max(1u, dstImage.extent.width >> dstMipLevel);
+        const Uint32 dstMipHeight = std::max(1u, dstImage.extent.height >> dstMipLevel);
         // Promoted for the same reason as the level range above, and it is the same bug class:
         // a VkImageCopy whose region runs past the image is an out-of-bounds promise to the
         // driver, and the frontend does not check the region at all (there is a CTS sibling,
@@ -9025,10 +9086,10 @@ void main() {
         // here: every target whose slices this function can address on one of the two Vulkan axes.
         // A refusal has to be a real decline, not an assertion - the assertion compiled to nothing
         // in a release build and the unsupported shape reached vkCmdCopyImage anyway.
-        CopyImageEndpoint srcEndpoint;
-        CopyImageEndpoint dstEndpoint;
-        if (!TryResolveCopyImageEndpoint(srcTextureTarget, *srcResource, srcMipLevel, srcZ, srcDepth, srcEndpoint) ||
-            !TryResolveCopyImageEndpoint(dstTextureTarget, *dstResource, dstMipLevel, dstZ, srcDepth, dstEndpoint)) {
+        CopyImageSliceMapping srcSlices;
+        CopyImageSliceMapping dstSlices;
+        if (!TryResolveCopyImageSliceMapping(srcTextureTarget, srcImage, srcMipLevel, srcZ, srcDepth, srcSlices) ||
+            !TryResolveCopyImageSliceMapping(dstTextureTarget, dstImage, dstMipLevel, dstZ, srcDepth, dstSlices)) {
             MGLOG_E_ONCE("%s: unsupported target pair src=%s dst=%s (srcZ=%d dstZ=%d depth=%d); declining the copy",
                          __func__, MG_Util::ConvertTextureTargetToString(srcTextureTarget).c_str(),
                          MG_Util::ConvertTextureTargetToString(dstTextureTarget).c_str(), srcZ, dstZ, srcDepth);
@@ -9039,40 +9100,53 @@ void main() {
         // shrinks) and a 3D texture by the selected level's depth (which every level halves), so
         // both come from the endpoint that resolved them.
         const Uint32 copySliceCount = static_cast<Uint32>(srcDepth);
-        if (srcEndpoint.baseSlice + copySliceCount > srcEndpoint.availableSlices ||
-            dstEndpoint.baseSlice + copySliceCount > dstEndpoint.availableSlices) {
+        if (srcSlices.baseSlice + copySliceCount > srcSlices.availableSlices ||
+            dstSlices.baseSlice + copySliceCount > dstSlices.availableSlices) {
             MGLOG_E_ONCE("%s: slice range outside image bounds (srcZ=%d of %u, dstZ=%d of %u, depth=%d); "
                          "declining the copy",
-                         __func__, srcZ, srcEndpoint.availableSlices, dstZ, dstEndpoint.availableSlices, srcDepth);
+                         __func__, srcZ, srcSlices.availableSlices, dstZ, dstSlices.availableSlices, srcDepth);
             return;
         }
 
-        const Bool clearReady = MaterializePendingClearForTexture(frame.commandBuffer, *srcTexture);
-        MOBILEGL_ASSERT(clearReady, "%s: failed to materialize pending clear for source textureId=%d",
-                        __func__, srcTexture->GetExternalIndex());
+        const auto materializeClear = [this, &frame](const CopyImageEndpoint& endpoint) {
+            if (endpoint.IsRenderbuffer()) {
+                return MaterializePendingClearForRenderbuffer(frame.commandBuffer, endpoint.Renderbuffer);
+            }
+            return MaterializePendingClearForTexture(frame.commandBuffer, *endpoint.Texture);
+        };
+        const Bool clearReady = materializeClear(srcEndpoint);
+        MOBILEGL_ASSERT(clearReady, "%s: failed to materialize pending clear for source objectId=%u",
+                        __func__, CopyImageEndpointName(srcEndpoint));
         // A clear still parked on the destination would otherwise materialize AFTER this copy and
         // wipe the texels it just wrote.
-        const Bool dstClearReady = MaterializePendingClearForTexture(frame.commandBuffer, *dstTexture);
-        MOBILEGL_ASSERT(dstClearReady, "%s: failed to materialize pending clear for destination textureId=%d",
-                        __func__, dstTexture->GetExternalIndex());
+        const Bool dstClearReady = materializeClear(dstEndpoint);
+        MOBILEGL_ASSERT(dstClearReady, "%s: failed to materialize pending clear for destination objectId=%u",
+                        __func__, CopyImageEndpointName(dstEndpoint));
 
-        const VkImageLayout srcOriginalLayout = srcResource->layout;
-        const VkImageLayout dstOriginalLayout = dstResource->layout;
+        const VkImageLayout srcOriginalLayout = *srcImage.trackedLayout;
+        const VkImageLayout dstOriginalLayout = *dstImage.trackedLayout;
         // A layout of UNDEFINED means nothing has ever been written to the image, which on the
         // SOURCE side is glTexStorage without an upload: legal GL, and the texels it copies are
         // undefined by the same spec sentence that lets the application ask. Both sides therefore
         // take the same shape - transition the whole image out of UNDEFINED and settle it on a
         // real layout afterwards, since UNDEFINED is not a layout a barrier may transition BACK to.
-        const auto resolveRestoreLayout = [copyAspectMask](VkImageLayout originalLayout) {
+        // A renderbuffer settles on its ATTACHMENT layout instead: it is never sampled, and that is
+        // the layout MaterializePendingClearForRenderbuffer leaves it in.
+        const auto resolveRestoreLayout = [copyAspectMask](VkImageLayout originalLayout, Bool isRenderbuffer) {
             if (originalLayout != VK_IMAGE_LAYOUT_UNDEFINED) {
                 return originalLayout;
             }
-            return (copyAspectMask & (VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT)) != 0
-                ? VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL
-                : VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
+            const Bool depthStencil =
+                (copyAspectMask & (VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT)) != 0;
+            if (isRenderbuffer) {
+                return depthStencil ? VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL
+                                    : VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            }
+            return depthStencil ? VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL
+                                : VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
         };
-        const VkImageLayout srcRestoreLayout = resolveRestoreLayout(srcOriginalLayout);
-        const VkImageLayout dstRestoreLayout = resolveRestoreLayout(dstOriginalLayout);
+        const VkImageLayout srcRestoreLayout = resolveRestoreLayout(srcOriginalLayout, srcImage.isRenderbuffer);
+        const VkImageLayout dstRestoreLayout = resolveRestoreLayout(dstOriginalLayout, dstImage.isRenderbuffer);
 
         VkPipelineStageFlags srcStageMask = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
         VkAccessFlags srcAccessMask = 0;
@@ -9083,15 +9157,15 @@ void main() {
         // [baseSlice, baseSlice + depth) the slice mapping above hands the copy.
         if (srcOriginalLayout == VK_IMAGE_LAYOUT_UNDEFINED) {
             Bool srcReady = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, srcResource->image, srcResource->layout, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
+                frame.commandBuffer, srcImage.image, *srcImage.trackedLayout, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
                 srcStageMask, VK_PIPELINE_STAGE_TRANSFER_BIT,
                 srcAccessMask, VK_ACCESS_TRANSFER_READ_BIT,
-                srcResource->aspect, 0, srcResource->mipLevels);
+                srcImage.aspect, 0, srcImage.mipLevels);
             MOBILEGL_ASSERT(srcReady, "%s: failed to transition undefined source image", __func__);
-            srcCopyLayout = srcResource->layout;
+            srcCopyLayout = *srcImage.trackedLayout;
         } else {
             Bool srcReady = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, srcResource->image, srcCopyLayout, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
+                frame.commandBuffer, srcImage.image, srcCopyLayout, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
                 srcStageMask, VK_PIPELINE_STAGE_TRANSFER_BIT,
                 srcAccessMask, VK_ACCESS_TRANSFER_READ_BIT, copyAspectMask, srcMipLevel, 1);
             MOBILEGL_ASSERT(srcReady, "%s: failed to transition source image", __func__);
@@ -9103,15 +9177,15 @@ void main() {
         VkImageLayout dstCopyLayout = dstOriginalLayout;
         if (dstOriginalLayout == VK_IMAGE_LAYOUT_UNDEFINED) {
             Bool dstReady = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, dstResource->image, dstResource->layout, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
+                frame.commandBuffer, dstImage.image, *dstImage.trackedLayout, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
                 dstStageMask, VK_PIPELINE_STAGE_TRANSFER_BIT,
                 dstAccessMask, VK_ACCESS_TRANSFER_WRITE_BIT,
-                dstResource->aspect, 0, dstResource->mipLevels);
+                dstImage.aspect, 0, dstImage.mipLevels);
             MOBILEGL_ASSERT(dstReady, "%s: failed to transition undefined destination image", __func__);
-            dstCopyLayout = dstResource->layout;
+            dstCopyLayout = *dstImage.trackedLayout;
         } else {
             Bool dstReady = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, dstResource->image, dstCopyLayout, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
+                frame.commandBuffer, dstImage.image, dstCopyLayout, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
                 dstStageMask, VK_PIPELINE_STAGE_TRANSFER_BIT,
                 dstAccessMask, VK_ACCESS_TRANSFER_WRITE_BIT, copyAspectMask, dstMipLevel, 1);
             MOBILEGL_ASSERT(dstReady, "%s: failed to transition destination image", __func__);
@@ -9121,18 +9195,18 @@ void main() {
         // on extent.depth as soon as either endpoint IS: a 3D image's subresource is always the
         // single layer (0, 1) and its slices are counted by the depth of the copy extent. With two
         // non-3D endpoints both layer counts carry it and extent.depth stays 1.
-        const Bool copyCrossesDepthAxis = srcEndpoint.slicesAreDepth || dstEndpoint.slicesAreDepth;
+        const Bool copyCrossesDepthAxis = srcSlices.slicesAreDepth || dstSlices.slicesAreDepth;
         VkImageCopy copyRegion{};
         copyRegion.srcSubresource.aspectMask = copyAspectMask;
         copyRegion.srcSubresource.mipLevel = srcMipLevel;
-        copyRegion.srcSubresource.baseArrayLayer = srcEndpoint.BaseArrayLayer();
-        copyRegion.srcSubresource.layerCount = srcEndpoint.slicesAreDepth ? 1u : copySliceCount;
-        copyRegion.srcOffset = {srcX, srcY, srcEndpoint.OffsetZ()};
+        copyRegion.srcSubresource.baseArrayLayer = srcSlices.BaseArrayLayer();
+        copyRegion.srcSubresource.layerCount = srcSlices.slicesAreDepth ? 1u : copySliceCount;
+        copyRegion.srcOffset = {srcX, srcY, srcSlices.OffsetZ()};
         copyRegion.dstSubresource.aspectMask = copyAspectMask;
         copyRegion.dstSubresource.mipLevel = dstMipLevel;
-        copyRegion.dstSubresource.baseArrayLayer = dstEndpoint.BaseArrayLayer();
-        copyRegion.dstSubresource.layerCount = dstEndpoint.slicesAreDepth ? 1u : copySliceCount;
-        copyRegion.dstOffset = {dstX, dstY, dstEndpoint.OffsetZ()};
+        copyRegion.dstSubresource.baseArrayLayer = dstSlices.BaseArrayLayer();
+        copyRegion.dstSubresource.layerCount = dstSlices.slicesAreDepth ? 1u : copySliceCount;
+        copyRegion.dstOffset = {dstX, dstY, dstSlices.OffsetZ()};
         copyRegion.extent = {static_cast<Uint32>(srcWidth), static_cast<Uint32>(srcHeight),
                              copyCrossesDepthAxis ? copySliceCount : 1u};
         MGLOG_D("CopyImageSubData: src(target=%s level=%u layer=%u+%u z=%d) -> dst(target=%s level=%u layer=%u+%u "
@@ -9143,8 +9217,8 @@ void main() {
                 copyRegion.dstSubresource.baseArrayLayer, copyRegion.dstSubresource.layerCount,
                 copyRegion.dstOffset.z, srcWidth, srcHeight, copyRegion.extent.depth);
         vkCmdCopyImage(frame.commandBuffer,
-                       srcResource->image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
-                       dstResource->image, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
+                       srcImage.image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
+                       dstImage.image, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL,
                        1, &copyRegion);
 
         VkPipelineStageFlags srcRestoreStageMask = VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT;
@@ -9152,14 +9226,14 @@ void main() {
         GetImageTransitionDestinationState(srcRestoreLayout, srcRestoreStageMask, srcRestoreAccessMask);
         if (srcOriginalLayout == VK_IMAGE_LAYOUT_UNDEFINED) {
             Bool srcRestored = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, srcResource->image, srcResource->layout, srcRestoreLayout,
+                frame.commandBuffer, srcImage.image, *srcImage.trackedLayout, srcRestoreLayout,
                 VK_PIPELINE_STAGE_TRANSFER_BIT, srcRestoreStageMask,
                 VK_ACCESS_TRANSFER_READ_BIT, srcRestoreAccessMask,
-                srcResource->aspect, 0, srcResource->mipLevels);
+                srcImage.aspect, 0, srcImage.mipLevels);
             MOBILEGL_ASSERT(srcRestored, "%s: failed to restore undefined source image layout", __func__);
         } else {
             Bool srcRestored = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, srcResource->image, srcCopyLayout, srcRestoreLayout,
+                frame.commandBuffer, srcImage.image, srcCopyLayout, srcRestoreLayout,
                 VK_PIPELINE_STAGE_TRANSFER_BIT, srcRestoreStageMask,
                 VK_ACCESS_TRANSFER_READ_BIT, srcRestoreAccessMask, copyAspectMask, srcMipLevel, 1);
             MOBILEGL_ASSERT(srcRestored, "%s: failed to restore source image layout", __func__);
@@ -9170,14 +9244,14 @@ void main() {
         GetImageTransitionDestinationState(dstRestoreLayout, dstRestoreStageMask, dstRestoreAccessMask);
         if (dstOriginalLayout == VK_IMAGE_LAYOUT_UNDEFINED) {
             Bool dstRestored = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, dstResource->image, dstResource->layout, dstRestoreLayout,
+                frame.commandBuffer, dstImage.image, *dstImage.trackedLayout, dstRestoreLayout,
                 VK_PIPELINE_STAGE_TRANSFER_BIT, dstRestoreStageMask,
                 VK_ACCESS_TRANSFER_WRITE_BIT, dstRestoreAccessMask,
-                dstResource->aspect, 0, dstResource->mipLevels);
+                dstImage.aspect, 0, dstImage.mipLevels);
             MOBILEGL_ASSERT(dstRestored, "%s: failed to restore undefined destination image layout", __func__);
         } else {
             Bool dstRestored = VkTextureManager::TransitionImageLayout(
-                frame.commandBuffer, dstResource->image, dstCopyLayout, dstRestoreLayout,
+                frame.commandBuffer, dstImage.image, dstCopyLayout, dstRestoreLayout,
                 VK_PIPELINE_STAGE_TRANSFER_BIT, dstRestoreStageMask,
                 VK_ACCESS_TRANSFER_WRITE_BIT, dstRestoreAccessMask, copyAspectMask, dstMipLevel, 1);
             MOBILEGL_ASSERT(dstRestored, "%s: failed to restore destination image layout", __func__);
@@ -9739,7 +9813,7 @@ void main() {
                                                        VkImageAspectFlags imageAspect, Uint32 mipLevel,
                                                        Uint32 baseArrayLayer, GLint x, GLint y, GLsizei width,
                                                        GLsizei height, GLenum format, GLenum type, void* pixels,
-                                                       Bool defaultFramebufferOrientation) {
+                                                       Bool defaultFramebufferOrientation, Uint32 sourceLayerCount) {
         const Bool wantDepth = format != GL_STENCIL_INDEX;
         const Bool wantStencil = format != GL_DEPTH_COMPONENT;
         auto& frame = m_frameContext.GetCurrent();
@@ -9818,6 +9892,10 @@ void main() {
             if (!mapped) return;
         }
 
+        // See the header: a stack of one-row layers and a single multi-row layer copy out to the
+        // same tightly-packed bytes, so only the region's shape splits the two cases.
+        const Uint32 copyLayerCount = std::max<Uint32>(sourceLayerCount, 1u);
+        const Uint32 copyRowCount = copyLayerCount > 1u ? 1u : copyExtent.height;
         VkBufferImageCopy regions[2]{};
         Uint32 regionCount = 0;
         if (wantDepth) {
@@ -9826,9 +9904,9 @@ void main() {
             region.imageSubresource.aspectMask = VK_IMAGE_ASPECT_DEPTH_BIT;
             region.imageSubresource.mipLevel = mipLevel;
             region.imageSubresource.baseArrayLayer = baseArrayLayer;
-            region.imageSubresource.layerCount = 1;
+            region.imageSubresource.layerCount = copyLayerCount;
             region.imageOffset = {copyOffset.x, copyOffset.y, 0};
-            region.imageExtent = {copyExtent.width, copyExtent.height, 1};
+            region.imageExtent = {copyExtent.width, copyRowCount, 1};
         }
         if (wantStencil) {
             auto& region = regions[regionCount++];
@@ -9836,9 +9914,9 @@ void main() {
             region.imageSubresource.aspectMask = VK_IMAGE_ASPECT_STENCIL_BIT;
             region.imageSubresource.mipLevel = mipLevel;
             region.imageSubresource.baseArrayLayer = baseArrayLayer;
-            region.imageSubresource.layerCount = 1;
+            region.imageSubresource.layerCount = copyLayerCount;
             region.imageOffset = {copyOffset.x, copyOffset.y, 0};
-            region.imageExtent = {copyExtent.width, copyExtent.height, 1};
+            region.imageExtent = {copyExtent.width, copyRowCount, 1};
         }
         vkCmdCopyImageToBuffer(frame.commandBuffer, image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL, readback.GetHandle(),
                                regionCount, regions);
@@ -10073,9 +10151,17 @@ void main() {
                     ? static_cast<Uint32>(textureUploadTarget) -
                         static_cast<Uint32>(TextureUploadTarget::CubeMapPositiveX)
                     : 0;
+                // A 1D array's levelSize.y() is its LAYER count, and those layers are the rows
+                // GL wants back - but in Vulkan they are array layers of a one-row image, not
+                // rows of layer 0, so the read has to be told which of the two it is looking at.
+                const Uint32 sourceLayers =
+                    textureObject->GetTarget() == TextureTarget::Texture1DArray
+                        ? static_cast<Uint32>(std::max<Int>(levelSize.y(), 1))
+                        : 1u;
                 ReadDepthStencilImageToClient(resource->image, resource->format, &resource->layout, resource->aspect,
                                               static_cast<Uint32>(level), arrayLayer, 0, 0, levelSize.x(),
-                                              levelSize.y(), format, type, pixels);
+                                              levelSize.y(), format, type, pixels,
+                                              /*defaultFramebufferOrientation=*/false, sourceLayers);
             } else {
                 MGLOG_E_ONCE("DirectVulkan::GetTexImage skipped: color query of a non-color texture");
             }
@@ -10093,12 +10179,19 @@ void main() {
         // destination layout (GL 3.3 section 6.1.4).
         const auto imageTextureTarget = textureObject->GetTarget();
         const Bool is3dImage = imageTextureTarget == TextureTarget::Texture3D;
-        const Bool isArrayImage = imageTextureTarget == TextureTarget::Texture1DArray ||
+        const Bool is1dArrayImage = imageTextureTarget == TextureTarget::Texture1DArray;
+        const Bool isArrayImage = is1dArrayImage ||
                                   imageTextureTarget == TextureTarget::Texture2DArray ||
                                   imageTextureTarget == TextureTarget::TextureCubeMapArray;
         const GLsizei depthSlices = is3dImage ? std::max<GLsizei>(texelSize.z(), 1) : 1;
         const GLsizei arrayLayers = isArrayImage ? static_cast<GLsizei>(resource->arrayLayers) : 1;
-        const GLsizei sliceCount = std::max<GLsizei>(depthSlices * arrayLayers, 1);
+        // A 1D array level comes back as ONE two-dimensional image whose rows are its layers
+        // (GL 4.6 core 8.11.4), so its layers are already counted by `height` above and must not
+        // multiply the slice count the way a 2D-array's or a cube-array's do. Vulkan still keeps
+        // them in arrayLayers on a one-row image, which is what the copy region below says - the
+        // two describe the same tightly-packed bytes.
+        const GLsizei sliceCount =
+            std::max<GLsizei>(depthSlices * (is1dArrayImage ? 1 : arrayLayers), 1);
         if (bufSize >= 0) {
             const Int dstChannels = GetReadbackChannelCount(format);
             if ((type == GL_UNSIGNED_BYTE || type == GL_FLOAT) && dstChannels > 0) {
@@ -10151,7 +10244,8 @@ void main() {
         copyRegion.imageSubresource.mipLevel = static_cast<Uint32>(level);
         copyRegion.imageSubresource.baseArrayLayer = 0;
         copyRegion.imageSubresource.layerCount = static_cast<Uint32>(arrayLayers);
-        copyRegion.imageExtent = {static_cast<Uint32>(width), static_cast<Uint32>(height),
+        copyRegion.imageExtent = {static_cast<Uint32>(width),
+                                  is1dArrayImage ? 1u : static_cast<Uint32>(height),
                                   static_cast<Uint32>(depthSlices)};
         vkCmdCopyImageToBuffer(frame.commandBuffer, resource->image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL,
                                readback.GetHandle(), 1, &copyRegion);

MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRenderer.h

@@ -23,6 +23,7 @@
 #include "VkTimerQueryManager.h"
 #include "MG_Util/Math/VectorTypes.h"
 #include <Includes.h>
+#include <MG_Backend/BackendObject.h>
 #include <vk_mem_alloc.h>
 
 #include "../VkIncludes.h"
@@ -197,9 +198,9 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                                   GLbitfield mask, GLenum filter);
         void CopyTexSubImage2D(GLenum target, GLint level, GLint xoffset, GLint yoffset,
                        GLint x, GLint y, GLsizei width, GLsizei height);
-        void CopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+        void CopyImageSubData(const CopyImageEndpoint& srcEndpoint,
                               GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                              const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                              const CopyImageEndpoint& dstEndpoint,
                               GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                               GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth);
         void GenerateMipmap(GLenum target);
@@ -216,10 +217,15 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         // depth/stencil image, which this renderer stores display-side-up: the copy rect then
         // has to be mapped out of GL's bottom-origin space and the copied rows re-oriented on
         // the way back, exactly as the colour ReadPixels path does.
+        // `sourceLayerCount` above 1 says the `height` rows the client is owed are stored as that
+        // many ARRAY LAYERS of a one-row image rather than as rows of one layer - the shape a GL
+        // 1D array has in Vulkan. The two produce byte-identical tightly-packed readbacks, so
+        // only the copy region differs; everything after it is written against `height`.
         void ReadDepthStencilImageToClient(VkImage image, VkFormat vkFormat, VkImageLayout* trackedLayout,
                                            VkImageAspectFlags imageAspect, Uint32 mipLevel, Uint32 baseArrayLayer,
                                            GLint x, GLint y, GLsizei width, GLsizei height, GLenum format, GLenum type,
-                                           void* pixels, Bool defaultFramebufferOrientation = false);
+                                           void* pixels, Bool defaultFramebufferOrientation = false,
+                                           Uint32 sourceLayerCount = 1);
         // Same-extent depth blit between images of different depth formats: host
         // round-trip with a per-texel re-encode (see BlitNamedFramebuffer).
         Bool BlitDepthAcrossFormats(FrameContext::FrameData& frame, VkImage srcImage, VkFormat srcFormat,

MobileGL/MG_Benchmark/CMakeLists.txt

@@ -43,4 +43,6 @@ set_tests_properties(SanityBench PROPERTIES LABELS benchmark)
 add_subdirectory(Program)
 add_subdirectory(Buffer)
 add_subdirectory(Driver)
-add_subdirectory(Container)
+add_subdirectory(Container)
+add_subdirectory(ShaderCache)
+add_subdirectory(Transpile)

MobileGL/MG_Benchmark/ShaderCache/CMakeLists.txt

@@ -0,0 +1,21 @@
+cmake_minimum_required(VERSION 3.24)
+
+add_executable(
+        TranslationCacheBench
+        TranslationCacheBench.cpp
+)
+
+target_include_directories(TranslationCacheBench PRIVATE
+        ${MGL_ROOT}/include
+        ${MGL_ROOT}/MobileGL
+        ${MGL_ROOT}/3rdparty/SPIRV-Reflect
+)
+
+target_link_libraries(
+        TranslationCacheBench PRIVATE
+        benchmark::benchmark
+        ${LINK_LIBRARIES}
+)
+
+add_test(NAME TranslationCacheBench COMMAND TranslationCacheBench --benchmark_counters_tabular=true)
+set_tests_properties(TranslationCacheBench PROPERTIES LABELS benchmark)

MobileGL/MG_Benchmark/ShaderCache/TranslationCacheBench.cpp

@@ -0,0 +1,457 @@
+// MobileGL - MobileGL/MG_Benchmark/ShaderCache/TranslationCacheBench.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+
+// What the two-level shader translation memo is worth, measured on the workload that
+// motivated it: the KHR-GL33.texture_swizzle.smoke_* shape, where one case builds 2592
+// programs out of a handful of distinct sources.
+//
+// Four pairs of cases, each Off/On:
+//
+//   ProgramLink      - the whole glCompileShader + glLinkProgram path for one program, with
+//                      FRESH SHADER OBJECTS every iteration. This is the CTS shape exactly,
+//                      and it is the headline case now. It used to be the PESSIMISTIC one:
+//                      a hit still paid for both glslang parses, because the parse happens
+//                      at glCompileShader - a different entry point from the one L1
+//                      memoizes - and fresh shader objects meant ShaderCompileAdoptionMap
+//                      could not hand the earlier parse over either. L1c is what closed
+//                      that: the compile half of the memo recognises each stage's source
+//                      and publishes its verdict without parsing, so on a hit this case now
+//                      constructs no glslang object at all.
+//
+//   SharedShaderLink - the same program population with the shader objects KEPT ALIVE, so
+//                      the parses happen once outside the measured loop whatever the cache
+//                      does. That makes it the CONTROL for L1c rather than a target: its
+//                      numbers should not move, and if they do, L1c has added cost to a
+//                      path it was supposed to leave alone.
+//
+//   DeferredParseLink - the shape where L1c could LOSE: a constant vertex source (which
+//                      hits L1c and therefore skips its parse) against a fresh fragment
+//                      source every iteration (which makes the PROGRAM key miss, so the
+//                      skipped parse has to happen inside the link after all). Same parse
+//                      count either way, so the pair should land within noise; see its own
+//                      header below.
+//
+//   EsslTranspile    - the DirectGLES backend segment: the SPIR-V pass chain plus
+//                      SPIRV-Cross. Runs the driver-INDEPENDENT half of the real chain (the
+//                      passes SyncToBackend runs unconditionally, plus the two stage-gated
+//                      ones a fragment module reaches) so the miss path costs what
+//                      production costs; the capability-gated passes need a live ES driver
+//                      and are not reachable from a benchmark process.
+//
+// Every On case runs with a warm cache: the first iteration misses and every one after it
+// hits, which is exactly the steady state of a 2592-program smoke case.
+
+#include <benchmark/benchmark.h>
+
+#include <string>
+
+#include "Config.h"
+#include "Includes.h"
+#include "Init.h"
+#include "MG_Impl/GLImpl/Program/GL_Program.h"
+#include "MG_State/GLState/Core.h"
+#include "MG_State/GLState/ProgramState/ProgramTranslationCache.h"
+#include "MG_Util/ShaderTranspiler/ShaderCompiler.h"
+#include "MG_Util/ShaderTranspiler/SpvcSession.h"
+#include "MG_Util/ShaderTranspiler/TranslationCache.h"
+#include "MG_Util/ShaderTranspiler/Types.h"
+
+using namespace MobileGL;
+using namespace MobileGL::MG_Util::ShaderTranspiler;
+
+namespace {
+    const char* kVertexSource = R"(#version 460
+layout(location = 0) in vec3 aPos;
+out vec3 vPos;
+out vec2 vUv;
+void main() {
+    vPos = aPos;
+    vUv = aPos.xy * 0.5 + 0.5;
+    gl_Position = vec4(aPos, 1.0);
+}
+)";
+
+    // Shaped after gl3cTextureSwizzleTests.cpp's template: a sampler of one type, one
+    // TEXTURE_ACCESS, one CHANNEL, and an output whose BASIC_TYPE is the only thing that
+    // varies within a case. Padded with enough real arithmetic that the translation chain
+    // is doing work rather than measuring fixed overheads.
+    // `padLines` = 0 is the honest CTS size: gl3cTextureSwizzleTests' smoke template is a
+    // handful of lines, and that is the workload the memo exists for. The padded variant is
+    // kept alongside it because a shaderpack stage is orders of magnitude bigger, and the
+    // two bracket the ratio the cache is worth in practice.
+    String SwizzleLikeFragment(const String& prefix, const int padLines) {
+        String source = "#version 460\n";
+        source += "in vec3 vPos;\n";
+        source += "in vec2 vUv;\n";
+        source += "layout(location = 0) out " + prefix + "vec4 fragColor;\n";
+        source += "uniform sampler2D uTex;\n";
+        source += "uniform vec4 uTint;\n";
+        source += "uniform mat4 uModel;\n";
+        source += "uniform float uArr[8];\n";
+        source += "void main() {\n";
+        source += "    vec4 s = texture(uTex, vUv);\n";
+        source += "    float acc = s.r;\n";
+        for (int i = 0; i < padLines; ++i) {
+            source += "    acc = acc * 1.0001 + sin(acc + " + std::to_string(i) + ".0) * cos(acc);\n";
+        }
+        source += "    for (int i = 0; i < 8; ++i) acc += uArr[i];\n";
+        source += "    vec4 p = uModel * vec4(vPos, 1.0);\n";
+        source += "    fragColor = " + prefix + "vec4((s + uTint) * acc + p);\n";
+        source += "}\n";
+        return source;
+    }
+
+    class CacheModeScope {
+    public:
+        explicit CacheModeScope(const Bool enabled)
+            : m_saved(MG_Config::Features.ShaderTranslationCache) {
+            MG_Config::Features.ShaderTranslationCache =
+                enabled ? MG_Config::QuirkOverride::ForceOn : MG_Config::QuirkOverride::ForceOff;
+        }
+        ~CacheModeScope() { MG_Config::Features.ShaderTranslationCache = m_saved; }
+
+    private:
+        const MG_Config::QuirkOverride m_saved;
+    };
+
+    class SyncCompileScope {
+    public:
+        SyncCompileScope() : m_saved(MG_Config::Features.AsyncShaderCompile) {
+            MG_Config::Features.AsyncShaderCompile = MG_Config::QuirkOverride::ForceOff;
+        }
+        ~SyncCompileScope() { MG_Config::Features.AsyncShaderCompile = m_saved; }
+
+    private:
+        const MG_Config::QuirkOverride m_saved;
+    };
+
+    // One program, built the way the CTS builds one: fresh shader objects every time.
+    void LinkOneProgram(const String& vertexSource, const String& fragmentSource) {
+        using namespace MG_Impl::GLImpl;
+        const GLuint vs = CreateShader(GL_VERTEX_SHADER);
+        const char* vsText = vertexSource.c_str();
+        ShaderSource(vs, 1, &vsText, nullptr);
+        CompileShader(vs);
+
+        const GLuint fs = CreateShader(GL_FRAGMENT_SHADER);
+        const char* fsText = fragmentSource.c_str();
+        ShaderSource(fs, 1, &fsText, nullptr);
+        CompileShader(fs);
+
+        const GLuint program = CreateProgram();
+        AttachShader(program, vs);
+        AttachShader(program, fs);
+        LinkProgram(program);
+        benchmark::DoNotOptimize(program);
+
+        DeleteProgram(program);
+        DeleteShader(vs);
+        DeleteShader(fs);
+    }
+
+    Vector<Uint32> BuildSanitizedFragmentSpirv(const String& fragmentSource) {
+        ShaderAttrib attrib{.shaderType = GL_FRAGMENT_SHADER, .sourceStr = fragmentSource};
+        auto shader = ShaderCompiler::CompileShader(attrib);
+        if (!shader) return {};
+        ProgramAttrib programAttrib{.shaders = {shader.value()}};
+        auto program = ShaderCompiler::LinkProgram(programAttrib);
+        if (!program) return {};
+        ProgramBinaryAttrib binaryAttrib{.shaderTypes = {GL_FRAGMENT_SHADER}, .program = *program.value()};
+        auto binary = ShaderCompiler::GetSpirvBinaryFromProgram(binaryAttrib);
+        if (!binary || binary->empty()) return {};
+        Vector<Uint32> sanitized;
+        if (!ShaderCompiler::SanitizeAndOptimizeBinary(binary->front(), sanitized)) return {};
+        return sanitized;
+    }
+
+    // The driver-independent part of BackendProgramObjectImpl::TranspileSpirvToEssl, in the
+    // same order. What is missing is only the capability-gated passes (viewport lowering,
+    // multisample clamping, noperspective emulation, the image-format bake), which cannot
+    // fire without a live ES driver to arm them.
+    Bool TranspileLikeDirectGles(const Vector<Uint32>& spirv, const Uint esslVersion, String& outEssl) {
+        Vector<Uint32> a;
+        const Vector<Uint32>* effective = &spirv;
+        if (ShaderCompiler::StripUboMemberRelaxedPrecisionForEssl(*effective, a, false) && !a.empty()) {
+            effective = &a;
+        }
+        Vector<Uint32> b;
+        if (ShaderCompiler::LowerRectImages(*effective, b, false) && !b.empty()) effective = &b;
+        Vector<Uint32> c;
+        if (ShaderCompiler::Lower1DArrayImagesForEssl(*effective, c, false) && !c.empty()) effective = &c;
+        Vector<Uint32> d;
+        if (ShaderCompiler::LegalizeFragmentOutputIndexingForEssl(*effective, d, false) && !d.empty()) {
+            effective = &d;
+        }
+
+        SpvcSession session(*effective, SessionUsageBit::Transpile);
+        spvc_compiler_options options;
+        if (session.CreateOptions(&options) != SPVC_SUCCESS) return false;
+        spvc_compiler_options_set_uint(options, SPVC_COMPILER_OPTION_GLSL_VERSION, esslVersion);
+        spvc_compiler_options_set_bool(options, SPVC_COMPILER_OPTION_GLSL_ES, SPVC_TRUE);
+        spvc_compiler_options_set_bool(options, SPVC_COMPILER_OPTION_GLSL_VULKAN_SEMANTICS, SPVC_FALSE);
+        session.SetOptions(options);
+        const char* result = nullptr;
+        session.Compile(&result);
+        if (!result) return false;
+        outEssl = result;
+        return true;
+    }
+
+    EsslTranslationKeyInputs EsslInputsFor(const Vector<Uint32>& spirv) {
+        EsslTranslationKeyInputs inputs;
+        inputs.spirv = &spirv;
+        inputs.shaderType = GL_FRAGMENT_SHADER;
+        inputs.maxColorTextureSamples = 4;
+        inputs.maxIntegerSamples = 1;
+        inputs.maxDepthTextureSamples = 4;
+        inputs.advertisedMaxSamples = 4;
+        inputs.esslVersion = 320;
+        return inputs;
+    }
+} // namespace
+
+// ---------------------------------------------------------------------------------------
+// L1, in situ: the full glCompileShader + glLinkProgram path for a repeated program.
+// ---------------------------------------------------------------------------------------
+// Arg(0) = the CTS smoke size; Arg(120) = a heavy stage, bracketing the ratio.
+static void BM_ProgramLink_CacheOff(benchmark::State& state) {
+    MobileGL::Initialize();
+    const SyncCompileScope sync;
+    const CacheModeScope cache(false);
+    const String vs = kVertexSource;
+    const String fs = SwizzleLikeFragment("", static_cast<int>(state.range(0)));
+    for (auto _ : state) {
+        LinkOneProgram(vs, fs);
+    }
+    state.SetLabel("MOBILEGL_SHADER_CACHE=0");
+}
+BENCHMARK(BM_ProgramLink_CacheOff)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+static void BM_ProgramLink_CacheOn(benchmark::State& state) {
+    MobileGL::Initialize();
+    const SyncCompileScope sync;
+    const CacheModeScope cache(true);
+    const String vs = kVertexSource;
+    const String fs = SwizzleLikeFragment("", static_cast<int>(state.range(0)));
+    LinkOneProgram(vs, fs); // prime, so the measured loop is the steady state
+    const TranslationCacheStats before = MG_State::GLState::GetProgramTranslationCache().Stats();
+    const TranslationCacheStats parseBefore = GetShaderParseVerdictCache().Stats();
+    for (auto _ : state) {
+        LinkOneProgram(vs, fs);
+    }
+    const TranslationCacheStats stats = MG_State::GLState::GetProgramTranslationCache().Stats();
+    const TranslationCacheStats parseStats = GetShaderParseVerdictCache().Stats();
+    state.counters["L1_hits"] = static_cast<double>(stats.hits - before.hits);
+    state.counters["L1_misses"] = static_cast<double>(stats.misses - before.misses);
+    // Two stages per iteration, so a clean run shows L1c_hits == 2 * iterations and zero
+    // misses: every glCompileShader in the loop skipped its parse.
+    state.counters["L1c_hits"] = static_cast<double>(parseStats.hits - parseBefore.hits);
+    state.counters["L1c_misses"] = static_cast<double>(parseStats.misses - parseBefore.misses);
+}
+BENCHMARK(BM_ProgramLink_CacheOn)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+// ---------------------------------------------------------------------------------------
+// L1, the shape the memo actually exists for: MANY PROGRAMS OUT OF THE SAME SHADERS.
+//
+// The pair above deletes its shader objects every iteration, which forces a fresh glslang
+// parse per iteration no matter what the link does - glCompileShader parses, and that is a
+// DIFFERENT entry point from the one L1 memoizes. It is a real workload (what an application
+// that never reuses a shader object pays) but it is the pessimistic one, and the residual it
+// leaves is the parse, not the link.
+//
+// This pair keeps the shader objects alive, so the parses happen once before the measured
+// loop and the L1 hit then skips the link, mapIO, the SPIR-V, the reflection and the routing
+// outright.
+//
+// SINCE L1c THIS IS THE CONTROL, NOT THE TARGET. Nothing inside the measured loop calls
+// glCompileShader, so L1c cannot fire here at all - which is exactly what makes the pair
+// useful: it is the shape that says whether the compile-side memo has slowed the LINK path
+// down. Its numbers should be indistinguishable from the pre-L1c ones.
+// ---------------------------------------------------------------------------------------
+namespace {
+    struct SharedShaders {
+        GLuint vs = 0;
+        GLuint fs = 0;
+    };
+
+    SharedShaders MakeSharedShaders(const String& vertexSource, const String& fragmentSource) {
+        using namespace MG_Impl::GLImpl;
+        SharedShaders shaders;
+        shaders.vs = CreateShader(GL_VERTEX_SHADER);
+        const char* vsText = vertexSource.c_str();
+        ShaderSource(shaders.vs, 1, &vsText, nullptr);
+        CompileShader(shaders.vs);
+        shaders.fs = CreateShader(GL_FRAGMENT_SHADER);
+        const char* fsText = fragmentSource.c_str();
+        ShaderSource(shaders.fs, 1, &fsText, nullptr);
+        CompileShader(shaders.fs);
+        return shaders;
+    }
+
+    void LinkFromSharedShaders(const SharedShaders& shaders) {
+        using namespace MG_Impl::GLImpl;
+        const GLuint program = CreateProgram();
+        AttachShader(program, shaders.vs);
+        AttachShader(program, shaders.fs);
+        LinkProgram(program);
+        benchmark::DoNotOptimize(program);
+        DeleteProgram(program);
+    }
+} // namespace
+
+static void BM_SharedShaderLink_CacheOff(benchmark::State& state) {
+    MobileGL::Initialize();
+    const SyncCompileScope sync;
+    const CacheModeScope cache(false);
+    const SharedShaders shaders =
+        MakeSharedShaders(kVertexSource, SwizzleLikeFragment("", static_cast<int>(state.range(0))));
+    for (auto _ : state) {
+        LinkFromSharedShaders(shaders);
+    }
+    state.SetLabel("MOBILEGL_SHADER_CACHE=0");
+}
+BENCHMARK(BM_SharedShaderLink_CacheOff)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+static void BM_SharedShaderLink_CacheOn(benchmark::State& state) {
+    MobileGL::Initialize();
+    const SyncCompileScope sync;
+    const CacheModeScope cache(true);
+    const SharedShaders shaders =
+        MakeSharedShaders(kVertexSource, SwizzleLikeFragment("", static_cast<int>(state.range(0))));
+    LinkFromSharedShaders(shaders); // prime, so the measured loop is the steady state
+    const TranslationCacheStats before = MG_State::GLState::GetProgramTranslationCache().Stats();
+    for (auto _ : state) {
+        LinkFromSharedShaders(shaders);
+    }
+    const TranslationCacheStats stats = MG_State::GLState::GetProgramTranslationCache().Stats();
+    state.counters["L1_hits"] = static_cast<double>(stats.hits - before.hits);
+    state.counters["L1_misses"] = static_cast<double>(stats.misses - before.misses);
+}
+BENCHMARK(BM_SharedShaderLink_CacheOn)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+// ---------------------------------------------------------------------------------------
+// L2, component: the DirectGLES SPIR-V pass chain plus SPIRV-Cross for one stage.
+// ---------------------------------------------------------------------------------------
+static void BM_EsslTranspile_CacheOff(benchmark::State& state) {
+    MobileGL::Initialize();
+    const Vector<Uint32> spirv =
+        BuildSanitizedFragmentSpirv(SwizzleLikeFragment("", static_cast<int>(state.range(0))));
+    if (spirv.empty()) {
+        state.SkipWithError("could not build the fragment module");
+        return;
+    }
+    String essl;
+    for (auto _ : state) {
+        if (!TranspileLikeDirectGles(spirv, 320, essl)) {
+            state.SkipWithError("transpile failed");
+            break;
+        }
+        benchmark::DoNotOptimize(essl.data());
+    }
+    state.SetLabel("MOBILEGL_SHADER_CACHE=0");
+}
+BENCHMARK(BM_EsslTranspile_CacheOff)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+static void BM_EsslTranspile_CacheOn(benchmark::State& state) {
+    MobileGL::Initialize();
+    const Vector<Uint32> spirv =
+        BuildSanitizedFragmentSpirv(SwizzleLikeFragment("", static_cast<int>(state.range(0))));
+    if (spirv.empty()) {
+        state.SkipWithError("could not build the fragment module");
+        return;
+    }
+    BoundedTranslationCache<EsslTranslationResult> cache("bench L2", 64, 8u << 20);
+    const EsslTranslationKeyInputs inputs = EsslInputsFor(spirv);
+    for (auto _ : state) {
+        const TranslationCacheKey key = BuildEsslTranslationKey(inputs);
+        EsslTranslationResultPtr hit = cache.Find(key);
+        if (!hit) {
+            auto payload = MakeShared<EsslTranslationResult>();
+            if (!TranspileLikeDirectGles(spirv, inputs.esslVersion, payload->essl)) {
+                state.SkipWithError("transpile failed");
+                break;
+            }
+            cache.Insert(key, EsslTranslationResultPtr(payload), EsslTranslationResultBytes(*payload));
+            hit = payload;
+        }
+        benchmark::DoNotOptimize(hit->essl.data());
+    }
+    const TranslationCacheStats stats = cache.Stats();
+    state.counters["L2_hits"] = static_cast<double>(stats.hits);
+    state.counters["L2_misses"] = static_cast<double>(stats.misses);
+}
+BENCHMARK(BM_EsslTranspile_CacheOn)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+// ---------------------------------------------------------------------------------------
+// L1c, the shape where it could LOSE rather than win: the DEFERRED PARSE.
+// ---------------------------------------------------------------------------------------
+// A stage whose compile hits L1c holds no AST, so if the program-level key then MISSES, the
+// parse it skipped has to happen anyway - inside the link, via ClaimParsedShader. The parse
+// is moved, not removed, and this pair is what says whether moving it costs anything.
+//
+// The shape forces exactly that, every iteration: one CONSTANT vertex source (hits L1c after
+// the first iteration) linked against a FRESH fragment source each time (misses L1c, and
+// makes the program key miss too). So:
+//
+//   cache off - two parses at glCompileShader, then the link.
+//   cache on  - one parse at glCompileShader (the fragment), one deferred parse inside the
+//               link (the vertex), then the link.
+//
+// The parse count is identical, so these two should land within noise of each other. If the
+// On arm is materially SLOWER, L1c is charging for something - the per-compile key build and
+// hash over the full preprocessed source, or the loss of the claim-CAS reuse - and that cost
+// shows up here and nowhere else.
+//
+// The distinct fragment sources also churn both front-end levels through their FIFO caps,
+// which is the eviction behaviour a real shaderpack load produces; over a long run the
+// constant vertex entry is occasionally evicted by that churn and re-inserted, so the L1c
+// hit rate reported below is high but not exactly 1.0 per iteration.
+namespace {
+    String UniqueFragmentSource(const Uint64 serial, const int padLines) {
+        return SwizzleLikeFragment("", padLines) +
+               "\n// unique-" + std::to_string(serial) + "\n";
+    }
+} // namespace
+
+static void BM_DeferredParseLink_CacheOff(benchmark::State& state) {
+    MobileGL::Initialize();
+    const SyncCompileScope sync;
+    const CacheModeScope cache(false);
+    const String vs = kVertexSource;
+    Uint64 serial = 0;
+    for (auto _ : state) {
+        LinkOneProgram(vs, UniqueFragmentSource(serial++, static_cast<int>(state.range(0))));
+    }
+    state.SetLabel("MOBILEGL_SHADER_CACHE=0");
+}
+BENCHMARK(BM_DeferredParseLink_CacheOff)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+static void BM_DeferredParseLink_CacheOn(benchmark::State& state) {
+    MobileGL::Initialize();
+    const SyncCompileScope sync;
+    const CacheModeScope cache(true);
+    const String vs = kVertexSource;
+    Uint64 serial = 0;
+    LinkOneProgram(vs, UniqueFragmentSource(~0ull, static_cast<int>(state.range(0)))); // prime the vertex entry
+    const TranslationCacheStats before = MG_State::GLState::GetProgramTranslationCache().Stats();
+    const TranslationCacheStats parseBefore = GetShaderParseVerdictCache().Stats();
+    for (auto _ : state) {
+        LinkOneProgram(vs, UniqueFragmentSource(serial++, static_cast<int>(state.range(0))));
+    }
+    const TranslationCacheStats stats = MG_State::GLState::GetProgramTranslationCache().Stats();
+    const TranslationCacheStats parseStats = GetShaderParseVerdictCache().Stats();
+    // Expected shape: L1 all misses (every program is new), L1c one hit (vertex) and one miss
+    // (fragment) per iteration.
+    state.counters["L1_hits"] = static_cast<double>(stats.hits - before.hits);
+    state.counters["L1_misses"] = static_cast<double>(stats.misses - before.misses);
+    state.counters["L1c_hits"] = static_cast<double>(parseStats.hits - parseBefore.hits);
+    state.counters["L1c_misses"] = static_cast<double>(parseStats.misses - parseBefore.misses);
+}
+BENCHMARK(BM_DeferredParseLink_CacheOn)->Arg(0)->Arg(120)->Unit(benchmark::kMicrosecond);
+
+BENCHMARK_MAIN();

MobileGL/MG_Benchmark/Transpile/CMakeLists.txt

@@ -0,0 +1,20 @@
+cmake_minimum_required(VERSION 3.24)
+
+# Deliberately NOT a google-benchmark target: the interesting quantity is a per-stage
+# breakdown of one program build, which needs its own clock around sub-steps that share
+# set-up, and a plain main() keeps the output a table this can be read straight out of.
+add_executable(
+        TranspileProfile
+        TranspileProfile.cpp
+)
+
+target_include_directories(TranspileProfile PRIVATE
+        ${MGL_ROOT}/include
+        ${MGL_ROOT}/MobileGL
+        ${MGL_ROOT}/3rdparty/SPIRV-Reflect
+)
+
+target_link_libraries(
+        TranspileProfile PRIVATE
+        ${LINK_LIBRARIES}
+)

MobileGL/MG_Impl/GLImpl/Buffer/Validators.cpp

@@ -13,6 +13,7 @@
 #include <MG_Util/Converters/GLToStr/GLEnumConverter.h>
 #include <MG_Util/Converters/MGToGL/BufferEnumConverter.h>
 #include <MG_Util/Converters/MGToStr/BufferEnumConverter.h>
+#include <MG_Util/ShaderTranspiler/Types.h>
 
 namespace MobileGL::MG_Impl::GLImpl::BufferImpl {
     Bool ValidateBufferTarget(BufferTarget target) {
@@ -67,6 +68,13 @@ namespace MobileGL::MG_Impl::GLImpl::BufferImpl {
                 // binding points in GL 3.3 (no ARB_transform_feedback3).
                 pointCount = std::min<SizeT>(pointCount, 4);
             }
+            if (target == BufferTarget::AtomicCounter) {
+                // GL_MAX_ATOMIC_COUNTER_BUFFER_BINDINGS, which is NOT the state layer's array
+                // size: a counter buffer reaches a shader only as a lowered storage block, so the
+                // reserved range is the ceiling, and glGetIntegerv advertises the same number.
+                pointCount = std::min<SizeT>(
+                    pointCount, static_cast<SizeT>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTER_BUFFER_BINDINGS));
+            }
             return pointCount;
         }
     } // namespace

MobileGL/MG_Impl/GLImpl/Drawing/GL_Drawing.cpp

@@ -108,6 +108,12 @@ namespace MobileGL::MG_Impl::GLImpl {
 
         const auto& program = MG_State::pGLContext->GetTransformFeedbackProgram();
         if (program != nullptr) {
+            // A geometry stage writes what it emits, not what the draw assembled, and the
+            // amplification factor lives in the shader. Record that this span contained such
+            // a draw so the transform feedback queries keep their backend result for it.
+            if (program->GetShaderIndexByStage(ShaderStage::Geometry) >= 0) {
+                MG_State::pGLContext->AddTransformFeedbackGeometryCaptureDraw();
+            }
             // Capacity in captured vertices = the tightest bound buffer.
             Uint64 capacityVertices = ~0ull;
             for (SizeT i = 0; i < program->GetTransformFeedbackBufferCount(); ++i) {
@@ -127,6 +133,11 @@ namespace MobileGL::MG_Impl::GLImpl {
         }
         MG_State::pGLContext->AddTransformFeedbackPrimitives(primitives);
         MG_State::pGLContext->AddTransformFeedbackCapturedVertices(primitives * verticesPerPrimitive);
+        // Only draws that get this far are in the written counter at all. The instanced and
+        // indirect entry points never call this function, so a span that contains one is NOT
+        // fully accounted, and the queries must be able to tell: they compare this counter's
+        // delta against zero before standing in for the backend's own result.
+        MG_State::pGLContext->AddTransformFeedbackAccountedCaptureDraw();
     }
 
     // Every primitive mode a draw command accepts (GL 4.6 core table 10.1, plus
@@ -151,11 +162,23 @@ namespace MobileGL::MG_Impl::GLImpl {
         }
     }
 
+    // The `mode` INVALID_ENUM in isolation, so a draw entry point can raise it BEFORE any of the
+    // state-dependent INVALID_OPERATIONs below. GL 4.6 core 10.4 makes a bad mode INVALID_ENUM
+    // unconditionally, while "no current program" is not even a spec-listed draw error - it is
+    // MobileGL's own null-dereference guard - so it must never shadow the enum check
+    // (KHR-GL31.api.coverage calls glDrawArraysInstanced/glDrawElementsInstanced with mode
+    // GL_POINTS-1 against a bare context and pins GL_INVALID_ENUM).
+    static Bool ValidatePrimitiveModeEnum(const char* functionName, GLenum mode) {
+        if (IsAcceptedPrimitiveMode(mode)) return true;
+
+        MG_State::pGLContext->RecordError(
+            ErrorCode::InvalidEnum,
+            MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName, "mode is not an accepted primitive type."));
+        return false;
+    }
+
     static Bool ValidatePrimitiveModeForBackend(const char* functionName, GLenum mode) {
-        if (!IsAcceptedPrimitiveMode(mode)) {
-            MG_State::pGLContext->RecordError(
-                ErrorCode::InvalidEnum,
-                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName, "mode is not an accepted primitive type."));
+        if (!ValidatePrimitiveModeEnum(functionName, mode)) {
             return false;
         }
 
@@ -303,10 +326,23 @@ namespace MobileGL::MG_Impl::GLImpl {
         }
     }
 
+    // GL 4.6 core 10.9: inside a conditional block whose predicate did not pass, the drawing
+    // commands, Clear, ClearBuffer* and the compute dispatches are DISCARDED. The gate sits on the
+    // wrappers that ISSUE the backend call rather than at the top of each entry point, so that
+    // everything a real driver would still do inside the block - argument validation and the
+    // errors it raises - happens exactly as it does outside one, and only the command itself is
+    // dropped. It is deliberately not on the frontend's transform-feedback accounting either:
+    // that mirrors what the capture stage would have written, and a conditional block around a
+    // capturing draw has no test coverage in either direction.
+    static Bool ConditionalRenderDiscardsCommand() {
+        return MG_State::pGLContext->ConditionalRenderDiscardsCommands();
+    }
+
     void Clear_Backend(GLbitfield mask) {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.Clear(mask);
     }
 
@@ -314,6 +350,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElements(mode, count, type, indices);
     }
 
@@ -322,6 +359,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElements(mode, count, type, indices, drawcount);
     }
 
@@ -330,6 +368,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElementsBaseVertex(mode, count, type, indices, drawcount,
                                                                           basevertex);
     }
@@ -338,6 +377,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArrays(mode, first, count);
     }
 
@@ -345,6 +385,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawArrays(mode, first, count, drawcount);
     }
 
@@ -353,6 +394,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsBaseVertex(mode, count, type, indices, basevertex);
     }
 
@@ -361,6 +403,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElementsIndirect(mode, type, indirect, drawcount, stride);
     }
 
@@ -368,6 +411,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawArraysIndirect(mode, indirect, drawcount, stride);
     }
 
@@ -376,6 +420,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawElementsIndirectCount(mode, type, indirect, drawcount,
                                                                              maxdrawcount, stride);
     }
@@ -385,6 +430,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.MultiDrawArraysIndirectCount(mode, indirect, drawcount, maxdrawcount,
                                                                            stride);
     }
@@ -394,6 +440,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawRangeElementsBaseVertex(mode, start, end, count, type, indices,
                                                                           basevertex);
     }
@@ -403,6 +450,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawRangeElements(mode, start, end, count, type, indices);
     }
 
@@ -412,6 +460,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstancedBaseVertexBaseInstance(
             mode, count, type, indices, instancecount, basevertex, baseinstance);
     }
@@ -421,6 +470,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstancedBaseVertex(mode, count, type, indices, instancecount,
                                                                               basevertex);
     }
@@ -430,6 +480,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstancedBaseInstance(mode, count, type, indices,
                                                                                 instancecount, baseinstance);
     }
@@ -439,6 +490,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsInstanced(mode, count, type, indices, instancecount);
     }
 
@@ -446,6 +498,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawElementsIndirect(mode, type, indirect);
     }
     void DrawArraysInstancedBaseInstance_Backend(GLenum mode, GLint first, GLsizei count, GLsizei instancecount,
@@ -453,6 +506,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArraysInstancedBaseInstance(mode, first, count, instancecount,
                                                                               baseinstance);
     }
@@ -461,6 +515,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArraysInstanced(mode, first, count, instancecount);
     }
 
@@ -468,6 +523,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 #ifdef TRACY_ENABLE
         ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
+        if (ConditionalRenderDiscardsCommand()) return;
         MG_Backend::gBackendFunctionsTable.GL.DrawArraysIndirect(mode, indirect);
     }
 
@@ -496,6 +552,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                 return;
             }
         }
+        // GL 4.3 added both dispatches to the conditional-render set (GL 4.6 core 10.9), which is
+        // exactly what KHR-GL43.compute_shader.conditional-dispatching checks.
+        if (ConditionalRenderDiscardsCommand()) return;
         dispatchCompute(numGroupsX, numGroupsY, numGroupsZ);
     }
 
@@ -547,6 +606,7 @@ namespace MobileGL::MG_Impl::GLImpl {
             return;
         }
         if (!ValidateCurrentProgramForCompute(__func__)) return;
+        if (ConditionalRenderDiscardsCommand()) return;
         dispatchComputeIndirect(indirect);
     }
 
@@ -596,12 +656,14 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void MultiDrawElementsIndirect(GLenum mode, GLenum type, const void* indirect, GLsizei drawcount, GLsizei stride) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         MultiDrawElementsIndirect_Backend(mode, type, indirect, drawcount, stride);
     }
 
     void MultiDrawArraysIndirect(GLenum mode, const void* indirect, GLsizei drawcount, GLsizei stride) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         MultiDrawArraysIndirect_Backend(mode, indirect, drawcount, stride);
@@ -715,12 +777,14 @@ namespace MobileGL::MG_Impl::GLImpl {
 
     void DrawRangeElementsBaseVertex(GLenum mode, GLuint start, GLuint end, GLsizei count, GLenum type,
                                      const void* indices, GLint basevertex) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawRangeElementsBaseVertex_Backend(mode, start, end, count, type, indices, basevertex);
     }
 
     void DrawRangeElements(GLenum mode, GLuint start, GLuint end, GLsizei count, GLenum type, const void* indices) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawRangeElements_Backend(mode, start, end, count, type, indices);
@@ -728,6 +792,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 
     void DrawElementsInstancedBaseVertexBaseInstance(GLenum mode, GLsizei count, GLenum type, const void* indices,
                                                      GLsizei instancecount, GLint basevertex, GLuint baseinstance) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawElementsInstancedBaseVertexBaseInstance_Backend(mode, count, type, indices, instancecount, basevertex,
@@ -736,6 +801,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 
     void DrawElementsInstancedBaseVertex(GLenum mode, GLsizei count, GLenum type, const void* indices,
                                          GLsizei instancecount, GLint basevertex) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawElementsInstancedBaseVertex_Backend(mode, count, type, indices, instancecount, basevertex);
@@ -743,18 +809,21 @@ namespace MobileGL::MG_Impl::GLImpl {
 
     void DrawElementsInstancedBaseInstance(GLenum mode, GLsizei count, GLenum type, const void* indices,
                                            GLsizei instancecount, GLuint baseinstance) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawElementsInstancedBaseInstance_Backend(mode, count, type, indices, instancecount, baseinstance);
     }
 
     void DrawElementsInstanced(GLenum mode, GLsizei count, GLenum type, const void* indices, GLsizei instancecount) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawElementsInstanced_Backend(mode, count, type, indices, instancecount);
     }
 
     void DrawElementsIndirect(GLenum mode, GLenum type, const void* indirect) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         if (!ValidateDrawElementsIndexType(__func__, type)) return;
@@ -764,18 +833,21 @@ namespace MobileGL::MG_Impl::GLImpl {
 
     void DrawArraysInstancedBaseInstance(GLenum mode, GLint first, GLsizei count, GLsizei instancecount,
                                          GLuint baseinstance) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawArraysInstancedBaseInstance_Backend(mode, first, count, instancecount, baseinstance);
     }
 
     void DrawArraysInstanced(GLenum mode, GLint first, GLsizei count, GLsizei instancecount) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         DrawArraysInstanced_Backend(mode, first, count, instancecount);
     }
 
     void DrawArraysIndirect(GLenum mode, const void* indirect) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         if (!ValidateIndirectDrawSource(__func__, indirect, kDrawArraysIndirectCommandBytes)) return;
@@ -783,6 +855,7 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void DrawElementsBaseVertex(GLenum mode, GLsizei count, GLenum type, const void* indices, GLint basevertex) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         AccountTransformFeedbackPrimitives(mode, count);
@@ -790,6 +863,7 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void DrawArrays(GLenum mode, GLint first, GLsizei count) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         AccountTransformFeedbackPrimitives(mode, count);
@@ -797,6 +871,7 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void MultiDrawArrays(GLenum mode, const GLint* first, const GLsizei* count, GLsizei drawcount) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         if (drawcount < 0) {
@@ -810,6 +885,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 
     void MultiDrawElements(GLenum mode, const GLsizei* count, GLenum type, const void* const* indices,
                            GLsizei drawcount) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         MultiDrawElements_Backend(mode, count, type, indices, drawcount);
@@ -817,6 +893,7 @@ namespace MobileGL::MG_Impl::GLImpl {
 
     void MultiDrawElementsBaseVertex(GLenum mode, const GLsizei* count, GLenum type, const void* const* indices,
                                      GLsizei drawcount, const GLint* basevertex) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         MultiDrawElementsBaseVertex_Backend(mode, count, type, indices, drawcount, basevertex);
@@ -827,6 +904,7 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void DrawElements(GLenum mode, GLsizei count, GLenum type, const void* indices) {
+        if (!ValidatePrimitiveModeEnum(__func__, mode)) return;
         if (!ValidateCurrentProgramForExecution(__func__)) return;
         if (!ValidatePrimitiveModeForBackend(__func__, mode)) return;
         AccountTransformFeedbackPrimitives(mode, count);

MobileGL/MG_Impl/GLImpl/Exporting/Definitions.cpp

@@ -725,8 +725,8 @@ DECLARE_GL_FUNCTION_STUB_HEAD(void, LoadName, GLuint name) DECLARE_GL_FUNCTION_S
 DECLARE_GL_FUNCTION_STUB_HEAD(void, PushName, GLuint name) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, PushName, name)
 DECLARE_GL_FUNCTION_STUB_HEAD(void, PopName) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, PopName)
 DECLARE_GL_FUNCTION_HEAD(void, ClampColor, GLenum target, GLenum clamp) DECLARE_GL_FUNCTION_END_NO_RETURN(void, ClampColor, target, clamp)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, BeginConditionalRender, GLuint id, GLenum mode) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, BeginConditionalRender, id, mode)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, EndConditionalRender, void) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, EndConditionalRender)
+DECLARE_GL_FUNCTION_HEAD(void, BeginConditionalRender, GLuint id, GLenum mode) DECLARE_GL_FUNCTION_END_NO_RETURN(void, BeginConditionalRender, id, mode)
+DECLARE_GL_FUNCTION_HEAD(void, EndConditionalRender) DECLARE_GL_FUNCTION_END_NO_RETURN(void, EndConditionalRender)
 DECLARE_GL_FUNCTION_HEAD(void, VertexAttribI1i, GLuint index, GLint x) DECLARE_GL_FUNCTION_END_NO_RETURN(void, VertexAttribI1i, index, x)
 DECLARE_GL_FUNCTION_HEAD(void, VertexAttribI2i, GLuint index, GLint x, GLint y) DECLARE_GL_FUNCTION_END_NO_RETURN(void, VertexAttribI2i, index, x, y)
 DECLARE_GL_FUNCTION_HEAD(void, VertexAttribI3i, GLuint index, GLint x, GLint y, GLint z) DECLARE_GL_FUNCTION_END_NO_RETURN(void, VertexAttribI3i, index, x, y, z)
@@ -982,7 +982,7 @@ DECLARE_GL_FUNCTION_HEAD(void, GetDoublei_v, GLenum target, GLuint index, GLdoub
 DECLARE_GL_FUNCTION_HEAD(void, DrawArraysInstancedBaseInstance, GLenum mode, GLint first, GLsizei count, GLsizei instancecount, GLuint baseinstance) DECLARE_GL_FUNCTION_END_NO_RETURN(void, DrawArraysInstancedBaseInstance, mode, first, count, instancecount, baseinstance)
 DECLARE_GL_FUNCTION_HEAD(void, DrawElementsInstancedBaseInstance, GLenum mode, GLsizei count, GLenum type, const void* indices, GLsizei instancecount, GLuint baseinstance) DECLARE_GL_FUNCTION_END_NO_RETURN(void, DrawElementsInstancedBaseInstance, mode, count, type, indices, instancecount, baseinstance)
 DECLARE_GL_FUNCTION_HEAD(void, DrawElementsInstancedBaseVertexBaseInstance, GLenum mode, GLsizei count, GLenum type, const void* indices, GLsizei instancecount, GLint basevertex, GLuint baseinstance) DECLARE_GL_FUNCTION_END_NO_RETURN(void, DrawElementsInstancedBaseVertexBaseInstance, mode, count, type, indices, instancecount, basevertex, baseinstance)
-DECLARE_GL_FUNCTION_STUB_HEAD(void, GetActiveAtomicCounterBufferiv, GLuint program, GLuint bufferIndex, GLenum pname, GLint* params) DECLARE_GL_FUNCTION_STUB_END_NO_RETURN(void, GetActiveAtomicCounterBufferiv, program, bufferIndex, pname, params)
+DECLARE_GL_FUNCTION_HEAD(void, GetActiveAtomicCounterBufferiv, GLuint program, GLuint bufferIndex, GLenum pname, GLint* params) DECLARE_GL_FUNCTION_END_NO_RETURN(void, GetActiveAtomicCounterBufferiv, program, bufferIndex, pname, params)
 DECLARE_GL_FUNCTION_HEAD(void, DrawTransformFeedbackInstanced, GLenum mode, GLuint id, GLsizei instancecount) DECLARE_GL_FUNCTION_END_NO_RETURN(void, DrawTransformFeedbackInstanced, mode, id, instancecount)
 DECLARE_GL_FUNCTION_HEAD(void, DrawTransformFeedbackStreamInstanced, GLenum mode, GLuint id, GLuint stream, GLsizei instancecount) DECLARE_GL_FUNCTION_END_NO_RETURN(void, DrawTransformFeedbackStreamInstanced, mode, id, stream, instancecount)
 DECLARE_GL_FUNCTION_HEAD(void, ClearBufferData, GLenum target, GLenum internalformat, GLenum format, GLenum type, const void* data) DECLARE_GL_FUNCTION_END_NO_RETURN(void, ClearBufferData, target, internalformat, format, type, data)

MobileGL/MG_Impl/GLImpl/Framebuffer/GL_Framebuffer.cpp

@@ -13,6 +13,7 @@
 #include <MG_Backend/BackendObjects.h>
 #include <MG_Util/Metrics/TextureMetrics.h>
 #include <MG_Impl/GLImpl/Texture/Validators.h>
+#include <MG_Impl/GLImpl/Getter/GL_Getter.h>
 #include <MG_State/GLState/ErrorState/Error.h>
 #include <MG_Util/Converters/GLToStr/GLEnumConverter.h>
 #include <MG_Util/Converters/GLToMG/TextureEnumConverter.h>
@@ -617,16 +618,17 @@ namespace MobileGL::MG_Impl::GLImpl {
         if (MG_Backend::pActiveBackendObject == nullptr) {
             return std::numeric_limits<Int>::max();
         }
-        return std::max(MG_Backend::pActiveBackendObject->GetDynamicParameters().MaxSamples, 1);
+        return GetAdvertisedMaxSamples();
     }
 
-    // GL_MAX_SAMPLES is the ceiling over all formats; an integer format has its own, lower
-    // one (GL_MAX_INTEGER_SAMPLES) and GL 4.6 core 9.2.4 makes exceeding it INVALID_OPERATION.
-    // The multisample TEXTURE path already resolves the limit per format
-    // (GL_Texture.cpp, GetMaxTextureSamplesForFormat); renderbuffers only ever compared
-    // against GL_MAX_SAMPLES, so on a driver where the two differ - Adreno reports
-    // GL_MAX_SAMPLES 4 and GL_MAX_INTEGER_SAMPLES 1 - an integer renderbuffer accepted a
-    // sample count the format cannot deliver, and said GL_NO_ERROR about it.
+    // GL_MAX_SAMPLES is the ceiling over all formats; an integer format has its own
+    // (GL_MAX_INTEGER_SAMPLES) and GL 4.6 core 9.2.4 makes exceeding it INVALID_OPERATION.
+    // The multisample TEXTURE path resolves the limit per format the same way
+    // (GL_Texture.cpp, GetMaxSupportedTextureSamples). Both are floored to the value MobileGL
+    // advertises: on a driver where the two differ - Adreno reports GL_MAX_SAMPLES 4 and
+    // GL_MAX_INTEGER_SAMPLES 1 - rejecting the advertised count here only moves the failure
+    // from the driver into MobileGL, so the frontend accepts it and the backend clamps the
+    // count it actually hands the driver.
     Int GetMaxRenderbufferSamplesForFormat_State(TextureInternalFormat format) {
         if (MG_Backend::pActiveBackendObject == nullptr) {
             return std::numeric_limits<Int>::max();
@@ -645,7 +647,10 @@ namespace MobileGL::MG_Impl::GLImpl {
         if (!isIntegerFormat) {
             return GetMaxRenderbufferSamples_State();
         }
-        return std::max(dynamicParameters.MaxIntegerSamples, 1);
+        // Per-format still, but never below the ceiling glGetIntegerv(GL_MAX_SAMPLES) promised:
+        // the driver's raw GL_MAX_INTEGER_SAMPLES stays the *backend* limit and the backend
+        // clamps to it, while the frontend honours what it advertised.
+        return std::max(dynamicParameters.MaxIntegerSamples, GetAdvertisedMaxSamples());
     }
 
     Bool ValidateRenderbufferStorageSize_State(GLsizei width, GLsizei height, const char* caller) {
@@ -2608,18 +2613,26 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void ClearBufferfi_Backend(GLenum buffer, GLint drawbuffer, GLfloat depth, GLint stencil) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferfi(buffer, drawbuffer, depth, stencil);
     }
 
     void ClearBufferfv_Backend(GLenum buffer, GLint drawbuffer, const GLfloat* value) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferfv(buffer, drawbuffer, value);
     }
 
     void ClearBufferuiv_Backend(GLenum buffer, GLint drawbuffer, const GLuint* value) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferuiv(buffer, drawbuffer, value);
     }
 
     void ClearBufferiv_Backend(GLenum buffer, GLint drawbuffer, const GLint* value) {
+        // GL 4.6 core 10.9 makes ClearBuffer* conditional alongside the drawing commands.
+        if (MG_State::pGLContext->ConditionalRenderDiscardsCommands()) return;
         MG_Backend::gBackendFunctionsTable.GL.ClearBufferiv(buffer, drawbuffer, value);
     }
 
@@ -3148,15 +3161,55 @@ namespace MobileGL::MG_Impl::GLImpl {
         GetNamedFramebufferAttachmentParameteriv_State(framebuffer, attachment, pname, params);
     }
 
+    // The three argument errors GL 4.6 core 18.3.1 asks a blit for. They have to be raised here,
+    // in the backend-independent frontend: DirectGLES drains the driver's error queue around the
+    // blit on purpose (that is how the resolve fallback probes the driver), so an ES-side
+    // rejection never reaches the application and glGetError() answered GL_NO_ERROR for a call
+    // the spec requires to fail (KHR-GL30.api.coverage's glBlitFramebuffer sub-check). DirectVulkan
+    // already dropped the bad-filter and LINEAR-with-depth/stencil calls on the floor with a log
+    // line (VulkanRenderer::BlitFramebuffer), so the only thing that changes for it is that the
+    // error is now visible where the spec says it should be.
+    static Bool ValidateBlitMaskAndFilter(const char* functionName, GLbitfield mask, GLenum filter) {
+        constexpr GLbitfield kBlitMaskBits = GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT;
+        if ((mask & ~kBlitMaskBits) != 0) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidValue,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName,
+                                             "mask contains bits other than GL_COLOR_BUFFER_BIT, "
+                                             "GL_DEPTH_BUFFER_BIT and GL_STENCIL_BUFFER_BIT."));
+            return false;
+        }
+        if (filter != GL_NEAREST && filter != GL_LINEAR) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidEnum,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName,
+                                             "filter must be GL_NEAREST or GL_LINEAR."));
+            return false;
+        }
+        // Depth and stencil have no meaningful interpolation, so GL_LINEAR is rejected outright
+        // rather than downgraded - even when the mask also carries the colour bit.
+        if (filter == GL_LINEAR && (mask & (GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT)) != 0) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidOperation,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", functionName,
+                                             "GL_LINEAR filtering is not allowed when mask includes "
+                                             "GL_DEPTH_BUFFER_BIT or GL_STENCIL_BUFFER_BIT."));
+            return false;
+        }
+        return true;
+    }
+
     void BlitNamedFramebuffer(GLuint readFramebuffer, GLuint drawFramebuffer, GLint srcX0, GLint srcY0, GLint srcX1,
                               GLint srcY1, GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1, GLbitfield mask,
                               GLenum filter) {
+        if (!ValidateBlitMaskAndFilter(__func__, mask, filter)) return;
         BlitNamedFramebuffer_State(readFramebuffer, drawFramebuffer, srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1,
                                    dstY1, mask, filter);
     }
 
     void BlitFramebuffer(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1, GLint dstX0, GLint dstY0, GLint dstX1,
                          GLint dstY1, GLbitfield mask, GLenum filter) {
+        if (!ValidateBlitMaskAndFilter(__func__, mask, filter)) return;
         BlitFramebuffer_Backend(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
     }
 

MobileGL/MG_Impl/GLImpl/Getter/GL_Getter.cpp

@@ -25,6 +25,7 @@
 #include <MG_State/GLState/FramebufferState/FramebufferObject.h>
 #include <MG_Util/Texture/TextureFormatProcessor.h>
 #include <MG_Util/Async/ShaderCompilePool.h>
+#include <MG_Util/ShaderTranspiler/Types.h>
 #include <MG_Backend/BackendObjects.h>
 
 namespace MobileGL::MG_Impl::GLImpl {
@@ -46,13 +47,29 @@ namespace MobileGL::MG_Impl::GLImpl {
             }
         }
 
-        constexpr GLint kFrontendMaxComputeUniformComponents = 1024;
-        constexpr GLint kFrontendMaxComputeAtomicCounters = 8;
-        constexpr GLint kFrontendMaxComputeAtomicCounterBuffers = 8;
+        // Shared with the glslang resource table for the same reason as the atomic-counter
+        // limits below: gl_MaxComputeUniformComponents expands from BuildTBuiltInResource.
+        constexpr GLint kFrontendMaxComputeUniformComponents =
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_COMPUTE_UNIFORM_COMPONENTS);
+        // Every atomic-counter limit is shared with the glslang resource table
+        // (BuildTBuiltInResource) through MG_Util/ShaderTranspiler/Types.h: GL 4.6 requires
+        // glGetIntegerv and the gl_MaxAtomicCounter* built-in constants to agree, and the two
+        // used to be independent tables that disagreed on both the binding count and the buffer
+        // size. Never move one of these without the other.
+        constexpr GLint kFrontendMaxComputeAtomicCounters =
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTERS_PER_STAGE);
+        constexpr GLint kFrontendMaxComputeAtomicCounterBuffers =
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTER_BUFFERS_PER_STAGE);
         constexpr GLint kFrontendMaxComputeSharedMemorySize = 32768;
         constexpr GLint kFrontendMaxComputeWorkGroupInvocations = 1024;
-        constexpr GLint kFrontendMaxCombinedAtomicCounters = 8;
-        constexpr GLint kFrontendMaxFragmentAtomicCounters = 8;
+        constexpr GLint kFrontendMaxCombinedAtomicCounters =
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTERS_PER_STAGE);
+        constexpr GLint kFrontendMaxCombinedAtomicCounterBuffers =
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTER_BUFFERS_PER_STAGE);
+        constexpr GLint kFrontendMaxFragmentAtomicCounters =
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTERS_PER_STAGE);
+        constexpr GLint kFrontendMaxFragmentAtomicCounterBuffers =
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTER_BUFFERS_PER_STAGE);
         constexpr GLint kFrontendMaxGeometryAtomicCounters = 0;
         constexpr GLint kFrontendMaxTessControlAtomicCounters = 0;
         constexpr GLint kFrontendMaxTessEvaluationAtomicCounters = 0;
@@ -66,10 +83,11 @@ namespace MobileGL::MG_Impl::GLImpl {
         constexpr GLint kFrontendMaxTessControlAtomicCounterBuffers = 0;
         constexpr GLint kFrontendMaxTessEvaluationAtomicCounterBuffers = 0;
         constexpr GLint kFrontendMaxVertexAtomicCounterBuffers = 0;
-        // One atomic counter is a uint, and a buffer never has to hold more counters than the
-        // combined limit the frontend advertises. GL 4.6 table 23.63 floors this at 32 bytes.
+        // GL_MAX_ATOMIC_COUNTER_BUFFER_SIZE: the byte offset ceiling a counter may be declared
+        // at. The matching binding count is applied in GetIndexedBufferQueryPointCount, so that
+        // the getter, the indexed queries and glBindBufferBase all share one ceiling.
         constexpr GLint kFrontendMaxAtomicCounterBufferSize =
-            kFrontendMaxCombinedAtomicCounters * static_cast<GLint>(sizeof(GLuint));
+            static_cast<GLint>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTER_BUFFER_SIZE);
         // KHR_debug minima (GL 4.6 table 23.66); the debug entry points are stubs, but the
         // limits they advertise still have to be legal.
         constexpr GLint kFrontendMaxDebugGroupStackDepth = 64;
@@ -103,12 +121,16 @@ namespace MobileGL::MG_Impl::GLImpl {
         constexpr GLint kFrontendSubpixelBits = 4;
         constexpr GLint kFrontendMaxSamples = 4;
 
+        // The floors under GL_MAX_COMPUTE_WORK_GROUP_COUNT / _SIZE. Shared with the compile
+        // pipeline (CaptureCompileEnv floors the same driver answers at them, and
+        // BuildTBuiltInResource expands gl_MaxComputeWorkGroup* from the result), because a
+        // shader is allowed to compare the built-in constant against this query.
         constexpr GLint GetMinComputeWorkGroupCount(GLuint index) {
-            return index < 3 ? 65535 : 0;
+            return index < 3 ? static_cast<GLint>(MG_Util::ShaderTranspiler::MIN_COMPUTE_WORK_GROUP_COUNT[index]) : 0;
         }
 
         constexpr GLint GetMinComputeWorkGroupSize(GLuint index) {
-            return index < 2 ? 1024 : (index == 2 ? 64 : 0);
+            return index < 3 ? static_cast<GLint>(MG_Util::ShaderTranspiler::MIN_COMPUTE_WORK_GROUP_SIZE[index]) : 0;
         }
 
         GLint GetMaxCombinedUniformComponents(GLint maxDefaultUniformComponents, GLint maxUniformBlocks,
@@ -186,6 +208,16 @@ namespace MobileGL::MG_Impl::GLImpl {
                     MG_Backend::pActiveBackendObject->GetDynamicParameters().MaxShaderStorageBufferBindings;
                 return std::min(frontendCount, static_cast<SizeT>(std::max(backendCount, 0)));
             }
+            if (bufferTarget == BufferTarget::AtomicCounter) {
+                // The counter family's binding count is NOT the state layer's array size: a
+                // counter buffer only reaches a shader as a lowered storage block, so what an
+                // implementation can serve is the reserved range, and that number is also what
+                // glslang compiles a layout(binding = N) atomic_uint against. Clamped here so
+                // GL_MAX_ATOMIC_COUNTER_BUFFER_BINDINGS, the indexed getters' index check and
+                // glBindBufferBase's all report the same ceiling.
+                return std::min(frontendCount,
+                                static_cast<SizeT>(MG_Util::ShaderTranspiler::MAX_ATOMIC_COUNTER_BUFFER_BINDINGS));
+            }
             return frontendCount;
         }
 
@@ -213,6 +245,23 @@ namespace MobileGL::MG_Impl::GLImpl {
             return ClampBlockCountToBindingPoints(blockCount, BufferTarget::ShaderStorage);
         }
 
+        // The per-stage GL_MAX_*_SHADER_STORAGE_BLOCKS answers. Backend-derived, and NOT a
+        // constant to be "restored" - these used to return a flat 16 for vertex, geometry and
+        // both tessellation stages, which is wrong on any host that does not serve storage
+        // blocks in those stages. Zero is a legal answer: GL 4.6 table 23.64 and ES 3.2 table
+        // 21.44 both set the minimum at 0 for every graphics stage except fragment, which is
+        // why the conformance suite gates each such test on the query instead of assuming it.
+        // ARM's GLES driver reports 0 for all four (a Mali-G925 does), and advertising 16 there
+        // bought nothing: the program still failed to link inside the backend, the frontend
+        // still reported LINK_STATUS as true, and every draw with it silently rendered nothing.
+        GLint StageStorageBlockCount(Int MG_Backend::DynamicBackendParameters::*stageLimit) {
+            static const MG_Backend::DynamicBackendParameters kBackendlessDefaults{};
+            const MG_Backend::DynamicBackendParameters& parameters =
+                MG_Backend::pActiveBackendObject ? MG_Backend::pActiveBackendObject->GetDynamicParameters()
+                                                 : kBackendlessDefaults;
+            return ClampStorageBlockCount(static_cast<GLint>(parameters.*stageLimit));
+        }
+
         bool TryDecodeDrawBufferQuery(GLenum pname, SizeT& drawBufferIndex) {
             if (pname == GL_DRAW_BUFFER) {
                 drawBufferIndex = 0;
@@ -422,6 +471,18 @@ namespace MobileGL::MG_Impl::GLImpl {
         }
     } // namespace
 
+    // GL 4.6 core table 23.53 requires GL_MAX_SAMPLES >= 4, so the driver's value is floored
+    // before it is advertised. Every other multisample ceiling MobileGL advertises has to be
+    // floored the same way: promising 4 samples globally while answering GL_MAX_INTEGER_SAMPLES
+    // 1 - which is exactly what Adreno reports - makes the frontend reject the very count it
+    // just told the application to use. The backends clamp the realised count instead.
+    GLint GetAdvertisedMaxSamples() {
+        if (MG_Backend::pActiveBackendObject == nullptr) {
+            return kFrontendMaxSamples;
+        }
+        return std::max(MG_Backend::pActiveBackendObject->GetDynamicParameters().MaxSamples, kFrontendMaxSamples);
+    }
+
     /* @INSERTION_POINT:FUNCTION_IMPLEMENTATION@ */
     const GLubyte* GetString(GLenum name) {
         static String vendorString;
@@ -1511,15 +1572,15 @@ namespace MobileGL::MG_Impl::GLImpl {
         case GL_LINE_WIDTH:
             *params = static_cast<GLint>(MG_State::pGLContext->GetLineWidth());
             return;
-        case GL_LAYER_PROVOKING_VERTEX:
-            *params = GL_LAST_VERTEX_CONVENTION;
-            return;
         case GL_LOGIC_OP_MODE:
             *params = static_cast<GLint>(MG_Util::ConvertLogicOperationToGLEnum(MG_State::pGLContext->GetLogicOp()));
             return;
         case GL_MAX_COMBINED_ATOMIC_COUNTERS:
             *params = kFrontendMaxCombinedAtomicCounters;
             return;
+        case GL_MAX_COMBINED_ATOMIC_COUNTER_BUFFERS:
+            *params = kFrontendMaxCombinedAtomicCounterBuffers;
+            return;
         case GL_MAX_COMBINED_UNIFORM_BLOCKS:
             *params = ClampUniformBlockCount(kFrontendMaxCombinedUniformBlocks);
             return;
@@ -1535,8 +1596,11 @@ namespace MobileGL::MG_Impl::GLImpl {
         case GL_MAX_FRAGMENT_ATOMIC_COUNTERS:
             *params = kFrontendMaxFragmentAtomicCounters;
             return;
+        case GL_MAX_FRAGMENT_ATOMIC_COUNTER_BUFFERS:
+            *params = kFrontendMaxFragmentAtomicCounterBuffers;
+            return;
         case GL_MAX_FRAGMENT_SHADER_STORAGE_BLOCKS:
-            *params = ClampStorageBlockCount(16); // TODO
+            *params = StageStorageBlockCount(&MG_Backend::DynamicBackendParameters::MaxFragmentShaderStorageBlocks);
             return;
         case GL_MAX_FRAGMENT_INPUT_COMPONENTS:
             *params = kFrontendMaxFragmentInputComponents;
@@ -1562,7 +1626,7 @@ namespace MobileGL::MG_Impl::GLImpl {
             *params = kFrontendMaxGeometryAtomicCounterBuffers;
             return;
         case GL_MAX_GEOMETRY_SHADER_STORAGE_BLOCKS:
-            *params = ClampStorageBlockCount(16); // TODO
+            *params = StageStorageBlockCount(&MG_Backend::DynamicBackendParameters::MaxGeometryShaderStorageBlocks);
             return;
         case GL_MAX_GEOMETRY_INPUT_COMPONENTS:
             *params = kFrontendMaxGeometryInputComponents;
@@ -1597,7 +1661,11 @@ namespace MobileGL::MG_Impl::GLImpl {
             *params = MG_State::pGLContext->IsCapabilityEnabled(CapabilityInput::Multisample) ? GL_TRUE : GL_FALSE;
             return;
         case GL_MIN_MAP_BUFFER_ALIGNMENT:
-            *params = 64; // TODO
+            // The same constant the map paths align to (MG_State/GLState/BufferState/
+            // PipeResource.h), never a literal: this number is a PROMISE about the pointers
+            // glMapBuffer and glMapBufferRange return, and the two used to be unrelated - the
+            // query said 64 while the pointers came out of a std::vector aligned to 16.
+            *params = static_cast<GLint>(MG_State::GLState::MIN_MAP_BUFFER_ALIGNMENT);
             return;
         case GL_MAX_LABEL_LENGTH:
             *params = 256; // TODO
@@ -1633,16 +1701,18 @@ namespace MobileGL::MG_Impl::GLImpl {
             *params = 0;
             return;
         case GL_MAX_TESS_CONTROL_SHADER_STORAGE_BLOCKS:
-            *params = ClampStorageBlockCount(16); // TODO
+            *params = StageStorageBlockCount(&MG_Backend::DynamicBackendParameters::MaxTessControlShaderStorageBlocks);
             return;
         case GL_MAX_TESS_EVALUATION_SHADER_STORAGE_BLOCKS:
-            *params = ClampStorageBlockCount(16); // TODO
+            *params =
+                StageStorageBlockCount(&MG_Backend::DynamicBackendParameters::MaxTessEvaluationShaderStorageBlocks);
             return;
         case GL_MAX_TEXTURE_LOD_BIAS:
             *params = 15; // TODO
             return;
         case GL_MAX_UNIFORM_LOCATIONS:
-            *params = 1024 * 4; // TODO
+            // The same constant the link's location allocator enforces - see ProgramObject.
+            *params = MG_State::GLState::ProgramObject::MAX_UNIFORM_LOCATIONS;
             return;
         case GL_MAX_VARYING_COMPONENTS:
             *params = kFrontendMaxVaryingComponents;
@@ -1662,7 +1732,7 @@ namespace MobileGL::MG_Impl::GLImpl {
                           : MG_Backend::DynamicBackendParameters{}.MaxVertexImageUniforms;
             return;
         case GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS:
-            *params = ClampStorageBlockCount(16); // TODO
+            *params = StageStorageBlockCount(&MG_Backend::DynamicBackendParameters::MaxVertexShaderStorageBlocks);
             return;
         case GL_MAX_VERTEX_UNIFORM_COMPONENTS:
             *params = kFrontendMaxVertexUniformComponents;
@@ -1972,6 +2042,24 @@ namespace MobileGL::MG_Impl::GLImpl {
         case GL_UNIFORM_BUFFER_START:
             RecordIndexedOnlyGetterError(__func__, pname);
             return;
+        // glBindBufferBase/Range set the GENERIC binding point too (GL 4.6 core 6.1.1), and this
+        // is the one indexed-buffer family whose non-indexed query was never answered - so it
+        // fell through to INVALID_ENUM and left the caller's variable holding whatever was in its
+        // stack slot. _START/_SIZE stay indexed-only, exactly like their uniform-buffer siblings.
+        case GL_ATOMIC_COUNTER_BUFFER_BINDING:
+            if (const auto& obj =
+                    MG_State::pGLContext->GetBufferBindingSlot(BufferTarget::AtomicCounter).GetBoundObject()) {
+                *params = static_cast<GLint>(obj->GetExternalIndex());
+            } else {
+                *params = 0;
+            }
+            return;
+        case GL_ATOMIC_COUNTER_BUFFER_START:
+            RecordIndexedOnlyGetterError(__func__, pname);
+            return;
+        case GL_ATOMIC_COUNTER_BUFFER_SIZE:
+            RecordIndexedOnlyGetterError(__func__, pname);
+            return;
         case GL_UNPACK_ALIGNMENT:
             *params = MG_State::pGLContext->GetPixelStoreParam(PixelStoreParam::UnpackAlignment);
             return;
@@ -2026,9 +2114,6 @@ namespace MobileGL::MG_Impl::GLImpl {
             params[3] = vp.w();
             return;
         }
-        case GL_VIEWPORT_INDEX_PROVOKING_VERTEX:
-            *params = GL_LAST_VERTEX_CONVENTION;
-            return;
         case GL_MAX_ELEMENT_INDEX:
             *params = 1024 * 1024; // TODO
             return;
@@ -2116,8 +2201,22 @@ namespace MobileGL::MG_Impl::GLImpl {
         case GL_MAX_CLIP_DISTANCES:
             *params = dynamicParameters.MaxClipDistances;
             break;
+        // Both were a hard-coded GL_LAST_VERTEX_CONVENTION, derived from nothing. GL 4.6 table
+        // 23.65 permits GL_UNDEFINED_VERTEX for either, and that is what the backends report
+        // wherever they do not actually pin a convention - claiming one is a statement about
+        // which vertex of a primitive supplies gl_Layer / gl_ViewportIndex, and DirectGLES
+        // rasterizes only viewport 0 on a driver without GL_OES_viewport_array while
+        // DirectVulkan picks its provoking mode per pipeline. KHR-GLxx.viewport_array.query
+        // accepts all four values, and .provoking_vertex - which failed on both devices, in
+        // OPPOSITE directions - stops verifying as soon as either answer is undefined.
+        case GL_LAYER_PROVOKING_VERTEX:
+            *params = static_cast<GLint>(dynamicParameters.LayerProvokingVertex);
+            break;
+        case GL_VIEWPORT_INDEX_PROVOKING_VERTEX:
+            *params = static_cast<GLint>(dynamicParameters.ViewportIndexProvokingVertex);
+            break;
         case GL_MAX_COLOR_TEXTURE_SAMPLES:
-            *params = dynamicParameters.MaxColorTextureSamples;
+            *params = std::max(dynamicParameters.MaxColorTextureSamples, GetAdvertisedMaxSamples());
             break;
         case GL_MAX_COMBINED_FRAGMENT_UNIFORM_COMPONENTS:
             *params = GetMaxCombinedUniformComponents(kFrontendMaxFragmentUniformComponents,
@@ -2147,7 +2246,7 @@ namespace MobileGL::MG_Impl::GLImpl {
             *params = dynamicParameters.MaxCubeMapTextureSize;
             break;
         case GL_MAX_DEPTH_TEXTURE_SAMPLES:
-            *params = dynamicParameters.MaxDepthTextureSamples;
+            *params = std::max(dynamicParameters.MaxDepthTextureSamples, GetAdvertisedMaxSamples());
             break;
         case GL_MAX_FRAMEBUFFER_WIDTH:
             *params = dynamicParameters.MaxFramebufferWidth;
@@ -2174,7 +2273,7 @@ namespace MobileGL::MG_Impl::GLImpl {
             *params = dynamicParameters.MaxComputeImageUniforms;
             break;
         case GL_MAX_INTEGER_SAMPLES:
-            *params = dynamicParameters.MaxIntegerSamples;
+            *params = std::max(dynamicParameters.MaxIntegerSamples, GetAdvertisedMaxSamples());
             break;
         case GL_MAX_RENDERBUFFER_SIZE:
             *params = dynamicParameters.MaxRenderbufferSize;
@@ -2207,18 +2306,19 @@ namespace MobileGL::MG_Impl::GLImpl {
                                                           static_cast<Uint64>(INT32_MAX)));
             break;
         case GL_MAX_ATOMIC_COUNTER_BUFFER_BINDINGS:
+            // NOT the frontend's binding-point array size: GetIndexedBufferQueryPointCount
+            // clamps this family to the range a lowered counter block can actually be served
+            // from, which is the same number glslang compiles a layout(binding = N) atomic_uint
+            // against and the same one glBindBufferBase validates an index against.
             *params = static_cast<GLint>(GetIndexedBufferQueryPointCount(BufferTarget::AtomicCounter));
             break;
         case GL_MAX_ATOMIC_COUNTER_BUFFER_SIZE:
             // The conformance suite splits this evenly across every advertised binding point and
             // binds all of them in one glBindBuffersRange
-            // (KHR-GL44.multi_bind.functional_bind_buffers_range), so the pair has to divide:
-            // 32 bytes over 36 binding points is a zero-sized range, which BindBufferRange
-            // rejects with INVALID_VALUE before it binds anything. Floor the advertised size at
-            // one counter per binding point.
-            *params = std::max<GLint>(
-                kFrontendMaxAtomicCounterBufferSize,
-                static_cast<GLint>(GetIndexedBufferQueryPointCount(BufferTarget::AtomicCounter) * sizeof(GLuint)));
+            // (KHR-GL44.multi_bind.functional_bind_buffers_range), so the pair has to divide -
+            // a zero-sized range is INVALID_VALUE before BindBufferRange binds anything. The
+            // shared constant is 16384 over 8 binding points, which divides.
+            *params = kFrontendMaxAtomicCounterBufferSize;
             break;
         case GL_MAX_TEXTURE_BUFFER_SIZE:
             *params = dynamicParameters.MaxTextureBufferSize;
@@ -2340,7 +2440,7 @@ namespace MobileGL::MG_Impl::GLImpl {
                                                         : dynamicParameters.MaxDrawBuffers;
             break;
         case GL_MAX_SAMPLES:
-            *params = std::max(dynamicParameters.MaxSamples, kFrontendMaxSamples);
+            *params = GetAdvertisedMaxSamples();
             break;
         case GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT:
             // Float state (see GetFloatv); rounded to nearest for the integer query per GL 3.3 6.1.2.

MobileGL/MG_Impl/GLImpl/Getter/GL_Getter.h

@@ -24,4 +24,8 @@ namespace MobileGL::MG_Impl::GLImpl {
     void GetInteger64i_v(GLenum target, GLuint index, GLint64* data);
     GLenum GetError();
     GLenum GetGraphicsResetStatus();
+    // The GL_MAX_SAMPLES value MobileGL advertises, i.e. the driver's value floored to the GL
+    // core minimum. Frontend multisample validators have to honour this ceiling for every
+    // format, otherwise MobileGL rejects a sample count it advertised itself.
+    GLint GetAdvertisedMaxSamples();
 } // namespace MobileGL::MG_Impl::GLImpl

MobileGL/MG_Impl/GLImpl/Program/GL_Program.cpp

@@ -21,6 +21,9 @@
 #include <MG_Backend/BackendObjects.h>
 
 namespace MobileGL::MG_Impl::GLImpl {
+    // The flattened uniform type these helpers used to take as a raw glslang::TType*
+    // pointing into the TProgram's pool allocator. See ProgramObject::TypeFacts.
+    using TypeFactsRef = const MG_State::GLState::ProgramObject::TypeFacts&;
     static GLint BoolToGLInt(bool value) {
         return value ? GL_TRUE : GL_FALSE;
     }
@@ -223,14 +226,14 @@ namespace MobileGL::MG_Impl::GLImpl {
         return false;
     }
 
-    GLint GetOpaqueUniformUnitLimit(const glslang::TType* type) {
+    GLint GetOpaqueUniformUnitLimit(const TypeFactsRef type) {
         const auto& dynamicParameters = MG_Backend::pActiveBackendObject->GetDynamicParameters();
-        if (type && type->isImage()) return dynamicParameters.MaxImageUnits;
-        if (type && type->isTexture()) return dynamicParameters.MaxCombinedTextureImageUnits;
+        if (type.isImage) return dynamicParameters.MaxImageUnits;
+        if (type.isTexture) return dynamicParameters.MaxCombinedTextureImageUnits;
         return 0;
     }
 
-    bool ValidateOpaqueUniformUnit(const char* functionName, const glslang::TType* type, GLint unit) {
+    bool ValidateOpaqueUniformUnit(const char* functionName, const TypeFactsRef type, GLint unit) {
         const GLint limit = GetOpaqueUniformUnitLimit(type);
         if (unit < 0 || unit >= limit) {
             MG_State::pGLContext->RecordError(
@@ -642,7 +645,13 @@ namespace MobileGL::MG_Impl::GLImpl {
             break;
         }
         case GL_ACTIVE_ATOMIC_COUNTER_BUFFERS:
-            *params = programObject->GetActiveAtomicCounterCount();
+            // Counter BUFFERS, not counters, and glslang's own getNumAtomicCounters() answers
+            // neither: the relaxed parse has already turned every atomic_uint into a plain uint
+            // member of a synthesized storage block by the time it builds its reflection, so it
+            // reports zero. The interface-query model recovers the buffers from those blocks and
+            // is what glGetProgramInterfaceiv(GL_ATOMIC_COUNTER_BUFFER, GL_ACTIVE_RESOURCES)
+            // already answers - the two queries are required to agree.
+            *params = ProgramInterface::GetActiveResourceCount(*programObject, GL_ATOMIC_COUNTER_BUFFER);
             MGLOG_D("%s: %s = %d", __func__, MG_Util::ConvertGLEnumToString(pname).c_str(), *params);
             break;
         case GL_ACTIVE_ATTRIBUTES:
@@ -856,10 +865,10 @@ namespace MobileGL::MG_Impl::GLImpl {
     // demotion makes a dmat4 a mat4 in the shader and a mat4-shaped slot here - but because it
     // is ROUTED differently: the caller's component-by-component EbtDouble branch has to widen
     // each float back to the queried type, and it undoes the same padding itself.
-    Bool TryGatherFloatMatrixColumns(const glslang::TType* ttype, const char* pBase, void* params) {
-        if (ttype == nullptr || !ttype->isMatrix() || ttype->getBasicType() == glslang::EbtDouble) return false;
-        const Int columns = ttype->getMatrixCols();
-        const Int rows = ttype->getMatrixRows();
+    Bool TryGatherFloatMatrixColumns(const TypeFactsRef ttype, const char* pBase, void* params) {
+        if (!ttype.isMatrix || ttype.isDouble) return false;
+        const Int columns = ttype.matrixCols;
+        const Int rows = ttype.matrixRows;
         for (Int column = 0; column < columns; ++column) {
             Memcpy(static_cast<char*>(params) + static_cast<SizeT>(column) * rows * sizeof(GLfloat),
                    pBase + static_cast<SizeT>(column) * 4 * sizeof(GLfloat), rows * sizeof(GLfloat));
@@ -871,7 +880,7 @@ namespace MobileGL::MG_Impl::GLImpl {
     // everything except a float matrix, whose padded columns make it wider. The rule itself
     // lives on ProgramObject, because the pipeline composite's uniform refresh needs the same
     // one and two copies of a layout rule is one too many.
-    SizeT UniformStorageSpanInBytes(const glslang::TType* ttype, SizeT tightSize) {
+    SizeT UniformStorageSpanInBytes(const TypeFactsRef ttype, SizeT tightSize) {
         return MG_State::GLState::ProgramObject::UniformStorageSpanInBytes(ttype, tightSize);
     }
 
@@ -904,7 +913,7 @@ namespace MobileGL::MG_Impl::GLImpl {
             auto offset = programObject->GetUniformOffset(location);
             auto size = programObject->GetUniformSizesInBytes(location);
             char* pUBO = (char*)programObject->MapUBO();
-            auto* ttype = programObject->GetUniformTType(location);
+            const auto& ttype = programObject->GetUniformTypeFacts(location);
             const SizeT span = UniformStorageSpanInBytes(ttype, size);
             if (pUBO == nullptr || offset == MG_State::GLState::ProgramObject::kInvalidUniformOffset ||
                 offset + span > programObject->GetUBOSize()) {
@@ -958,7 +967,7 @@ namespace MobileGL::MG_Impl::GLImpl {
         auto offset = programObject->GetUniformOffset(location);
         auto size = programObject->GetUniformSizesInBytes(location);
         char* pUBO = static_cast<char*>(programObject->MapUBO());
-        auto* ttype = programObject->GetUniformTType(location);
+        const auto& ttype = programObject->GetUniformTypeFacts(location);
         const SizeT span = UniformStorageSpanInBytes(ttype, size);
         if (pUBO == nullptr || offset == MG_State::GLState::ProgramObject::kInvalidUniformOffset ||
             offset + span > programObject->GetUBOSize()) {
@@ -981,10 +990,10 @@ namespace MobileGL::MG_Impl::GLImpl {
         // conversion rules (7.6: round to nearest for the integer queries) apply; the value
         // widens back to the queried type, having lost precision at the glUniform*d that
         // stored it and not here.
-        if (ttype->getBasicType() == glslang::EbtDouble) {
-            const Int columns = ttype->isMatrix() ? ttype->getMatrixCols() : 1;
-            const Int rows = ttype->isMatrix() ? ttype->getMatrixRows()
-                                               : (ttype->isVector() ? ttype->getVectorSize() : 1);
+        if (ttype.isDouble) {
+            const Int columns = ttype.isMatrix ? ttype.matrixCols : 1;
+            const Int rows = ttype.isMatrix ? ttype.matrixRows
+                                               : (ttype.isVector ? ttype.vectorSize : 1);
             // std140 gives every matrix column its own 16-byte slot; a non-matrix is one
             // tightly packed run and never reaches the stride at all.
             const SizeT columnStride = 4 * sizeof(GLfloat);
@@ -1191,8 +1200,8 @@ namespace MobileGL::MG_Impl::GLImpl {
             Memcpy(pUBO + offset + byteOffsetInsideUniform, value, writeSize);
             programObject.MarkUBOContentDirty();
         } else {
-            auto* ttype = programObject.GetUniformTType(location);
-            if (!ttype->isTexture() && !ttype->isImage()) return;
+            const auto& ttype = programObject.GetUniformTypeFacts(location);
+            if (!ttype.isTexture && !ttype.isImage) return;
             if constexpr (!std::is_same_v<std::remove_cv_t<T>, GLint> || ItemCount != 1) {
                 MG_State::pGLContext->RecordError(
                     ErrorCode::InvalidOperation,
@@ -2835,6 +2844,73 @@ namespace MobileGL::MG_Impl::GLImpl {
         return ProgramInterface::GetResourceLocationIndex(*programObject, programInterface, name);
     }
 
+    // GL 4.6 §7.7. Every property this reports is one the GL_ATOMIC_COUNTER_BUFFER interface
+    // already carries, so this is a rename of glGetProgramResourceiv's props onto the older
+    // entry point's - and the two are required to agree, which is only true while both read the
+    // same model. It was a silent stub: it wrote nothing, raised nothing, and left every probe
+    // reading its own uninitialised output.
+    static Bool TryMapActiveAtomicCounterBufferProp(GLenum pname, GLenum& outProp) {
+        switch (pname) {
+        case GL_ATOMIC_COUNTER_BUFFER_BINDING:
+            outProp = GL_BUFFER_BINDING;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_DATA_SIZE:
+            outProp = GL_BUFFER_DATA_SIZE;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_ACTIVE_ATOMIC_COUNTERS:
+            outProp = GL_NUM_ACTIVE_VARIABLES;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_ACTIVE_ATOMIC_COUNTER_INDICES:
+            outProp = GL_ACTIVE_VARIABLES;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_VERTEX_SHADER:
+            outProp = GL_REFERENCED_BY_VERTEX_SHADER;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_TESS_CONTROL_SHADER:
+            outProp = GL_REFERENCED_BY_TESS_CONTROL_SHADER;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_TESS_EVALUATION_SHADER:
+            outProp = GL_REFERENCED_BY_TESS_EVALUATION_SHADER;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_GEOMETRY_SHADER:
+            outProp = GL_REFERENCED_BY_GEOMETRY_SHADER;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_FRAGMENT_SHADER:
+            outProp = GL_REFERENCED_BY_FRAGMENT_SHADER;
+            return true;
+        case GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_COMPUTE_SHADER:
+            outProp = GL_REFERENCED_BY_COMPUTE_SHADER;
+            return true;
+        default:
+            return false;
+        }
+    }
+
+    void GetActiveAtomicCounterBufferiv(GLuint program, GLuint bufferIndex, GLenum pname, GLint* params) {
+        auto& programObject = TryToGetProgramForInterfaceQuery(program, __func__);
+        if (!programObject) return;
+        GLenum prop = GL_NONE;
+        if (!TryMapActiveAtomicCounterBufferProp(pname, prop)) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidEnum,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
+                                             "pname is not an active atomic counter buffer property."));
+            return;
+        }
+        Vector<GLint> values;
+        if (!ProgramInterface::GetResourceProp(*programObject, GL_ATOMIC_COUNTER_BUFFER, bufferIndex, prop, values)) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidValue,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
+                                             "bufferIndex is not an active atomic counter buffer index."));
+            return;
+        }
+        if (params == nullptr) return;
+        // GL_ATOMIC_COUNTER_BUFFER_ACTIVE_ATOMIC_COUNTER_INDICES is the only multi-value property
+        // here, and the caller sized its array from _ACTIVE_ATOMIC_COUNTERS.
+        for (SizeT i = 0; i < values.size(); ++i) params[i] = values[i];
+    }
+
     // GL 4.6 §7.6.2: <storageBlockIndex> is an active shader storage block index of <program>
     // - that is, exactly what glGetProgramResourceIndex(GL_SHADER_STORAGE_BLOCK) returned.
     // Since wave 2 that index is the interface-query layer's, so this is where the one index

MobileGL/MG_Impl/GLImpl/Program/GL_Program.h

@@ -140,6 +140,7 @@ namespace MobileGL::MG_Impl::GLImpl {
                               const GLenum* props, GLsizei bufSize, GLsizei* length, GLint* params);
     GLint GetProgramResourceLocation(GLuint program, GLenum programInterface, const GLchar* name);
     GLint GetProgramResourceLocationIndex(GLuint program, GLenum programInterface, const GLchar* name);
+    void GetActiveAtomicCounterBufferiv(GLuint program, GLuint bufferIndex, GLenum pname, GLint* params);
     void ShaderStorageBlockBinding(GLuint program, GLuint storageBlockIndex, GLuint storageBlockBinding);
     void Uniform1d(GLint location, GLdouble v0);
     void Uniform1dv(GLint location, GLsizei count, const GLdouble* value);

MobileGL/MG_Impl/GLImpl/Program/ProgramInterface.cpp

@@ -19,7 +19,7 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
         // "<getAtomicCounterBlockName()>_<binding>" (ParseContextBase.cpp), one per GL
         // atomic-counter binding point. That block IS the GL_ATOMIC_COUNTER_BUFFER resource
         // and its trailing number IS GL_BUFFER_BINDING; its members stay GL_UNIFORMs.
-        constexpr const char* kAtomicCounterBlockPrefix = "gl_AtomicCounterBlock";
+        constexpr const char* kAtomicCounterBlockPrefix = MG_Util::ShaderTranspiler::ATOMIC_COUNTER_BLOCK_PREFIX;
 
         enum class BlockKind {
             Uniform,       // a real GL uniform block
@@ -81,19 +81,18 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
         // The enumerated spelling of an array resource is "name[0]". glslang already applies
         // that to uniforms and buffer variables (EShReflectionBasicArraySuffix), but never to
         // stage inputs/outputs, so those get it here.
-        String WithArraySuffix(const String& name, const glslang::TType* type) {
-            if (type == nullptr || !type->isArray() || EndsWithZeroSubscript(name)) return name;
+        String WithArraySuffix(const String& name, const ProgramObject::TypeFacts& type) {
+            if (!type.isArray || EndsWithZeroSubscript(name)) return name;
             return name + "[0]";
         }
 
         // GL_ARRAY_SIZE: element count for a sized array, 0 for a runtime-sized one
         // (a shader storage block's unsized trailing member), 1 for a non-array.
-        GLint ArraySizeOf(const glslang::TType* type, GLint reflectedSize) {
-            if (type != nullptr && type->isArray()) {
-                if (!type->isSizedArray()) return 0;
-                return type->getOuterArraySize();
-            }
-            return reflectedSize < 1 ? 1 : reflectedSize;
+        // `record.arraySize` is already the sized-array/reflected-size resolution; the only
+        // extra rule here is GL's 0 for a runtime-sized array.
+        GLint ArraySizeOf(const ProgramObject::ResourceReflection& record) {
+            if (record.type.isArray && !record.type.isSizedArray) return 0;
+            return record.arraySize;
         }
 
         // Two spellings name the same resource when they are equal, or differ only by the
@@ -174,22 +173,21 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
             return static_cast<GLint>(element);
         }
 
-        BlockKind ClassifyBlock(const glslang::TObjectReflection& block) {
+        BlockKind ClassifyBlock(const ProgramObject::BlockReflection& block) {
             if (std::strstr(block.name.c_str(), MG_Util::ShaderTranspiler::GLOBAL_UBO_NAME) != nullptr) {
                 return BlockKind::GlobalUbo;
             }
             if (IsAtomicCounterBlockName(block.name)) return BlockKind::AtomicCounter;
-            const glslang::TType* type = block.getType();
-            if (type != nullptr && type->getQualifier().storage == glslang::EvqBuffer) return BlockKind::Storage;
+            if (block.type.isBuffer) return BlockKind::Storage;
             return BlockKind::Uniform;
         }
 
         // std140/std430 column stride, the same vec4-rounded rule ProgramObject applies to
         // uniform matrices. 0 for a non-matrix.
-        GLint MatrixStrideOf(const glslang::TType* type) {
-            if (type == nullptr || !type->isMatrix()) return 0;
-            const bool rowMajor = type->getQualifier().layoutMatrix == glslang::ElmRowMajor;
-            const int strideVectorComponents = rowMajor ? type->getMatrixCols() : type->getMatrixRows();
+        GLint MatrixStrideOf(const ProgramObject::TypeFacts& type) {
+            if (!type.isMatrix) return 0;
+            const bool rowMajor = type.layoutMatrix == static_cast<Int>(glslang::ElmRowMajor);
+            const int strideVectorComponents = rowMajor ? type.matrixCols : type.matrixRows;
             constexpr int scalarSize = 4;
             const int vectorAlignment = (strideVectorComponents <= 1)    ? scalarSize
                                         : (strideVectorComponents == 2) ? 2 * scalarSize
@@ -197,9 +195,9 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
             return (vectorAlignment + 15) & ~15;
         }
 
-        GLint IsRowMajorOf(const glslang::TType* type) {
-            if (type == nullptr || !type->isMatrix()) return 0;
-            return type->getQualifier().layoutMatrix == glslang::ElmRowMajor ? 1 : 0;
+        GLint IsRowMajorOf(const ProgramObject::TypeFacts& type) {
+            if (!type.isMatrix) return 0;
+            return type.layoutMatrix == static_cast<Int>(glslang::ElmRowMajor) ? 1 : 0;
         }
 
         GLint MappedLocation(Int rawLocation) {
@@ -227,12 +225,12 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
         // Note the union is used even when it is empty: an array element nobody dereferenced has
         // no member bits and is genuinely referenced by nobody, which is the whole point - falling
         // back to the block's own mask there would restore the over-approximation.
-        Vector<Uint32> BuildBlockStagesFromMembers(const glslang::TProgram& reflection, Int blockCount) {
-            auto& mutableReflection = const_cast<glslang::TProgram&>(reflection);
+        Vector<Uint32> BuildBlockStagesFromMembers(const ProgramObject::LinkArtifacts& reflection,
+                                                    Int blockCount) {
             Vector<Uint32> stagesByBlock(static_cast<SizeT>(blockCount < 0 ? 0 : blockCount), 0u);
-            const Int uniformCount = mutableReflection.getNumUniformVariables();
+            const Int uniformCount = static_cast<Int>(reflection.uniformReflection.size());
             for (Int index = 0; index < uniformCount; ++index) {
-                const auto& uniform = mutableReflection.getUniform(index);
+                const auto& uniform = reflection.uniformReflection[index];
                 const Int owner = uniform.index;
                 if (owner < 0 || owner >= blockCount) continue;
                 stagesByBlock[static_cast<SizeT>(owner)] |= static_cast<Uint32>(uniform.stages);
@@ -250,7 +248,7 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
         // ss[1] and requires both to report the fragment stage, which only glslang's own
         // (deliberately over-approximating) block mask gets right. Storage and atomic-counter
         // blocks therefore keep that mask untouched.
-        Uint32 UniformBlockStages(const glslang::TObjectReflection& block, const Vector<Uint32>& stagesFromMembers,
+        Uint32 UniformBlockStages(const ProgramObject::BlockReflection& block, const Vector<Uint32>& stagesFromMembers,
                                   Int tIndex) {
             String arrayBase;
             Uint element = 0;
@@ -264,15 +262,15 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
             return stagesFromMembers[static_cast<SizeT>(tIndex)];
         }
 
-        void BuildBlocks(ProgramObject& program, const glslang::TProgram& reflection, Model& model,
+        void BuildBlocks(ProgramObject& program, const ProgramObject::LinkArtifacts& reflection, Model& model,
                          Vector<BlockKind>& blockKind, Vector<Int>& blockInterfaceIndex) {
-            const Int blockCount = const_cast<glslang::TProgram&>(reflection).getNumUniformBlocks();
+            const Int blockCount = static_cast<Int>(reflection.blockReflection.size());
             blockKind.assign(blockCount, BlockKind::Uniform);
             blockInterfaceIndex.assign(blockCount, -1);
             const Vector<Uint32> stagesFromMembers = BuildBlockStagesFromMembers(reflection, blockCount);
 
             for (Int tIndex = 0; tIndex < blockCount; ++tIndex) {
-                const auto& block = const_cast<glslang::TProgram&>(reflection).getUniformBlock(tIndex);
+                const auto& block = reflection.blockReflection[tIndex];
                 const BlockKind kind = ClassifyBlock(block);
                 blockKind[tIndex] = kind;
                 if (kind == BlockKind::AtomicCounter) {
@@ -293,7 +291,7 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
                     // glShaderStorageBlockBinding wins over the declaration (GL 4.6 §7.6.2 -
                     // exactly the same rule GL_UNIFORM_BLOCK follows through
                     // GetUniformBlockBinding below).
-                    const GLint declared = block.getBinding();
+                    const GLint declared = block.binding;
                     resource.bufferBinding = declared < 0 ? 0 : declared + BlockArrayElement(block.name);
                     const Int rebound = program.GetShaderStorageBlockBindingOverride(block.name);
                     if (rebound >= 0) resource.bufferBinding = static_cast<GLint>(rebound);
@@ -315,21 +313,22 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
                 resource.bufferDataSize = static_cast<GLint>(program.GetUBOSizeAt(glIndex));
                 const Int tIndex = program.TProgramBlockIndex(static_cast<Uint>(glIndex));
                 if (tIndex >= 0 && tIndex < blockCount) {
-                    resource.stages = UniformBlockStages(const_cast<glslang::TProgram&>(reflection).getUniformBlock(tIndex),
+                    resource.stages = UniformBlockStages(reflection.blockReflection[tIndex],
                                                       stagesFromMembers, tIndex);
                 }
                 model.uniformBlocks.push_back(Move(resource));
             }
         }
 
-        void BuildUniformsAndBufferVariables(ProgramObject& program, const glslang::TProgram& reflection, Model& model,
+        void BuildUniformsAndBufferVariables(ProgramObject& program,
+                                             const ProgramObject::LinkArtifacts& reflection, Model& model,
                                              const Vector<BlockKind>& blockKind,
                                              const Vector<Int>& blockInterfaceIndex) {
             const Uint uniformCount = program.GetUniformCount();
             for (Uint glIndex = 0; glIndex < uniformCount; ++glIndex) {
                 const Int tIndex = program.TProgramUniformIndex(glIndex);
-                const auto& refl = const_cast<glslang::TProgram&>(reflection).getUniform(tIndex);
-                const glslang::TType* type = refl.getType();
+                const auto& refl = ProgramObject::UniformAtIn(reflection, tIndex);
+                const auto& type = refl.type;
                 const Int owner = refl.index;
                 const BlockKind kind = (owner >= 0 && owner < static_cast<Int>(blockKind.size()))
                                            ? blockKind[owner]
@@ -338,7 +337,7 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
                 Resource resource;
                 resource.name = refl.name;
                 resource.type = static_cast<GLenum>(refl.glDefineType);
-                resource.arraySize = ArraySizeOf(type, refl.size);
+                resource.arraySize = ArraySizeOf(refl);
                 resource.stages = static_cast<Uint32>(refl.stages);
 
                 if (kind == BlockKind::Storage) {
@@ -414,17 +413,13 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
         // program that redeclares `out gl_PerVertex { vec4 gl_Position; }` still carries
         // gl_PointSize and gl_ClipDistance through the block-unwrapping reflection, and they
         // are not part of its output interface.
-        Bool IsHiddenBlockMember(const glslang::TType* type) {
-            return type != nullptr && type->getBasicType() == glslang::EbtVoid;
-        }
+        Bool IsHiddenBlockMember(const ProgramObject::TypeFacts& type) { return type.isVoid; }
 
-        void BuildStageIO(ProgramObject& program, const glslang::TProgram& reflection, Model& model) {
-            auto& mutableReflection = const_cast<glslang::TProgram&>(reflection);
-
-            const Int inputCount = mutableReflection.getNumPipeInputs();
+        void BuildStageIO(ProgramObject& program, const ProgramObject::LinkArtifacts& reflection, Model& model) {
+            const Int inputCount = static_cast<Int>(reflection.pipeInputReflection.size());
             for (Int index = 0; index < inputCount; ++index) {
-                const auto& refl = mutableReflection.getPipeInput(index);
-                const glslang::TType* type = refl.getType();
+                const auto& refl = reflection.pipeInputReflection[index];
+                const auto& type = refl.type;
                 if (IsHiddenBlockMember(type)) continue;
                 Resource resource;
                 // The Vulkan-semantics parse reflects the vertex builtins under their SPIR-V
@@ -432,10 +427,10 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
                 const String& glName = ProgramObject::NormalizeBuiltinPipeInputName(refl.name);
                 resource.name = WithArraySuffix(glName, type);
                 resource.type = static_cast<GLenum>(refl.glDefineType);
-                resource.arraySize = ArraySizeOf(type, refl.size);
+                resource.arraySize = ArraySizeOf(refl);
                 resource.location = program.GetAttributeLocation(refl.name);
-                if (resource.location < 0) resource.location = MappedLocation(static_cast<Int>(refl.layoutLocation()));
-                resource.isPerPatch = (type != nullptr && type->getQualifier().patch) ? 1 : 0;
+                if (resource.location < 0) resource.location = MappedLocation(refl.location);
+                resource.isPerPatch = type.isPatch ? 1 : 0;
                 resource.stages = static_cast<Uint32>(refl.stages);
                 model.programInputs.push_back(Move(resource));
             }
@@ -447,16 +442,16 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
             // carries its own layout(location=N)), and a location then manufactures a color
             // index of 0 where GL requires -1
             // (KHR-GL43.program_interface_query.separate-programs-tess-control).
-            const Bool lastStageIsFragment = mutableReflection.getIntermediate(EShLangFragment) != nullptr;
-            const Int outputCount = mutableReflection.getNumPipeOutputs();
+            const Bool lastStageIsFragment = reflection.lastStageIsFragment;
+            const Int outputCount = static_cast<Int>(reflection.pipeOutputReflection.size());
             for (Int index = 0; index < outputCount; ++index) {
-                const auto& refl = mutableReflection.getPipeOutput(index);
-                const glslang::TType* type = refl.getType();
+                const auto& refl = reflection.pipeOutputReflection[index];
+                const auto& type = refl.type;
                 if (IsHiddenBlockMember(type)) continue;
                 Resource resource;
                 resource.name = WithArraySuffix(refl.name, type);
                 resource.type = static_cast<GLenum>(refl.glDefineType);
-                resource.arraySize = ArraySizeOf(type, refl.size);
+                resource.arraySize = ArraySizeOf(refl);
                 resource.location = MappedLocation(program.GetFragmentDataLocation(refl.name.c_str()));
                 if (resource.location < 0 || !lastStageIsFragment) {
                     // A built-in output (gl_FragDepth, gl_SampleMask) has no location, and a
@@ -467,11 +462,11 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
                     resource.locationIndex = program.GetFragmentDataIndex(refl.name.c_str());
                     // glBindFragDataLocationIndexed wins; otherwise the shader's
                     // layout(index = N), which the frag-data maps never saw.
-                    if (resource.locationIndex == 0 && type != nullptr && type->getQualifier().hasIndex()) {
-                        resource.locationIndex = static_cast<GLint>(type->getQualifier().layoutIndex);
+                    if (resource.locationIndex == 0 && type.hasIndex) {
+                        resource.locationIndex = static_cast<GLint>(type.layoutIndex);
                     }
                 }
-                resource.isPerPatch = (type != nullptr && type->getQualifier().patch) ? 1 : 0;
+                resource.isPerPatch = type.isPatch ? 1 : 0;
                 resource.stages = static_cast<Uint32>(refl.stages);
                 model.programOutputs.push_back(Move(resource));
             }
@@ -511,15 +506,14 @@ namespace MobileGL::MG_Impl::GLImpl::ProgramInterface {
         Model BuildModel(ProgramObject& program) {
             Model model;
             if (!program.GetLinkStatus()) return model;
-            const glslang::TProgram* reflection = program.GetReflection();
-            if (reflection == nullptr) return model;
+            const ProgramObject::LinkArtifacts& reflection = program.GetLinkReflection();
             model.valid = true;
 
             Vector<BlockKind> blockKind;
             Vector<Int> blockInterfaceIndex;
-            BuildBlocks(program, *reflection, model, blockKind, blockInterfaceIndex);
-            BuildUniformsAndBufferVariables(program, *reflection, model, blockKind, blockInterfaceIndex);
-            BuildStageIO(program, *reflection, model);
+            BuildBlocks(program, reflection, model, blockKind, blockInterfaceIndex);
+            BuildUniformsAndBufferVariables(program, reflection, model, blockKind, blockInterfaceIndex);
+            BuildStageIO(program, reflection, model);
             BuildXfb(program, model);
             return model;
         }

MobileGL/MG_Impl/GLImpl/Query/GL_Query.cpp

@@ -31,8 +31,15 @@ namespace MobileGL::MG_Impl::GLImpl {
             Bool ended = false;
             Bool resultCached = false;
             Uint64 cachedResult = 0;
-            // Transform feedback primitive counter at BeginQuery time.
+            // The transform feedback primitive counter matching this query's target, at
+            // BeginQuery time.
             Uint64 counterSnapshot = 0;
+            // Capture-draw counters at BeginQuery time: how many capture draws the CPU
+            // accounting had reproduced exactly, and how many of those it could not (a
+            // geometry stage amplifies). Their deltas decide whether the CPU result may
+            // stand in for the backend's.
+            Uint64 accountedCaptureDrawSnapshot = 0;
+            Uint64 geometryCaptureDrawSnapshot = 0;
         };
 
         // Query calls may arrive from any thread (launchers migrate the context
@@ -122,6 +129,46 @@ namespace MobileGL::MG_Impl::GLImpl {
             g_activeTimeElapsedQueryId = 0;
         }
 
+        // The CPU accounting counter a transform feedback query target reads: what the capture
+        // buffers took for GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, and everything the capture
+        // stage assembled - a paused span included - for GL_PRIMITIVES_GENERATED. One counter
+        // for both targets would report the clamped written count as the generated one.
+        Uint64 TransformFeedbackCounterForTarget(GLenum target) {
+            return target == GL_PRIMITIVES_GENERATED
+                       ? MG_State::pGLContext->GetTransformFeedbackGeneratedCounter()
+                       : MG_State::pGLContext->GetTransformFeedbackPrimitiveCounter();
+        }
+
+        // The span's CPU accounting delta. Saturating: a snapshot left above its counter (a
+        // context switch between Begin and End, a counter that never moved) would otherwise
+        // wrap to 2^64-1, which GetQueryObjectuiv hands the app as 4294967295.
+        Uint64 TransformFeedbackCpuResult(const QueryObject* queryObject) {
+            const Uint64 counter = TransformFeedbackCounterForTarget(queryObject->target);
+            return counter > queryObject->counterSnapshot ? counter - queryObject->counterSnapshot : 0;
+        }
+
+        // Whether this ended span's result should come from the CPU accounting rather than from
+        // the backend query it also ran. Three conditions, all necessary:
+        //   * the backend asked for it (DirectGLES, whose ES driver counter is the unreliable
+        //     one; DirectVulkan never sets the bit and so is untouched by any of this);
+        //   * the target is PRIMITIVES_WRITTEN. GL_PRIMITIVES_GENERATED counts primitives
+        //     whether or not a capture is active, and the accounting only ever sees capture
+        //     draws, so the backend's counter is the more complete answer there;
+        //   * the span was fully accounted: at least one capture draw reached the accounting
+        //     (the instanced, indirect and multi-draw entry points do not call it at all, so a
+        //     span made of those is invisible to it) and none of them amplified through a
+        //     geometry stage, which the CPU cannot model.
+        Bool PrefersCpuTransformFeedbackResult(const QueryObject* queryObject) {
+            if (!MG_Backend::gBackendFunctionsTable.GL.PrefersCpuXfbPrimitiveAccounting) return false;
+            if (queryObject->target != GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN) return false;
+            if (MG_State::pGLContext->GetTransformFeedbackGeometryCaptureDraws() !=
+                queryObject->geometryCaptureDrawSnapshot) {
+                return false;
+            }
+            return MG_State::pGLContext->GetTransformFeedbackAccountedCaptureDraws() !=
+                   queryObject->accountedCaptureDrawSnapshot;
+        }
+
         // Shared GetQueryObject* implementation. Returns false when an error
         // was recorded and no value should be written back. `outValueProduced`, when given,
         // additionally distinguishes "succeeded with a value" from "succeeded but the result is not
@@ -407,7 +454,11 @@ namespace MobileGL::MG_Impl::GLImpl {
             const auto beginXfbPrimitivesQuery = MG_Backend::gBackendFunctionsTable.GL.BeginXfbPrimitivesQuery;
             queryObject->backendHandle =
                 beginXfbPrimitivesQuery ? beginXfbPrimitivesQuery(target == GL_PRIMITIVES_GENERATED) : nullptr;
-            queryObject->counterSnapshot = MG_State::pGLContext->GetTransformFeedbackPrimitiveCounter();
+            queryObject->counterSnapshot = TransformFeedbackCounterForTarget(target);
+            queryObject->accountedCaptureDrawSnapshot =
+                MG_State::pGLContext->GetTransformFeedbackAccountedCaptureDraws();
+            queryObject->geometryCaptureDrawSnapshot =
+                MG_State::pGLContext->GetTransformFeedbackGeometryCaptureDraws();
         } else if (isOcclusionQuery) {
             queryObject->backendHandle = MG_Backend::gBackendFunctionsTable.GL.BeginOcclusionQuery();
         } else {
@@ -448,12 +499,21 @@ namespace MobileGL::MG_Impl::GLImpl {
                 if (const auto endXfbPrimitivesQuery = MG_Backend::gBackendFunctionsTable.GL.EndXfbPrimitivesQuery) {
                     endXfbPrimitivesQuery(queryObject->backendHandle);
                 }
-                // Result comes from the GPU query at read time.
-            } else {
-                queryObject->cachedResult =
-                    MG_State::pGLContext->GetTransformFeedbackPrimitiveCounter() - queryObject->counterSnapshot;
+            }
+            // A backend query that is not going to be read is released here, not left to be
+            // collected later: the span is over, the driver object has nothing left to say.
+            // Ending it first is what makes that legal.
+            if (!queryObject->backendHandle || PrefersCpuTransformFeedbackResult(queryObject)) {
+                if (queryObject->backendHandle) {
+                    if (const auto deleteBackendQuery = MG_Backend::gBackendFunctionsTable.GL.DeleteBackendQuery) {
+                        deleteBackendQuery(queryObject->backendHandle);
+                    }
+                    queryObject->backendHandle = nullptr;
+                }
+                queryObject->cachedResult = TransformFeedbackCpuResult(queryObject);
                 queryObject->resultCached = true;
             }
+            // Otherwise the result comes from the GPU query at read time.
             queryObject->active = false;
             queryObject->ended = true;
             activeQueryId = 0;
@@ -505,6 +565,75 @@ namespace MobileGL::MG_Impl::GLImpl {
         queryObject->ended = true;
     }
 
+    void BeginConditionalRender(GLuint id, GLenum mode) {
+        // GL 4.6 core 10.9's eight modes. The _INVERTED half flips the sense of the predicate;
+        // the BY_REGION half only narrows WHERE an implementation is permitted to discard, so
+        // treating it as its whole-framebuffer sibling is what an implementation without region
+        // granularity does. The _NO_WAIT half is a permission to render rather than stall, not an
+        // obligation - see the resolve below.
+        Bool inverted = false;
+        switch (mode) {
+        case GL_QUERY_WAIT:
+        case GL_QUERY_NO_WAIT:
+        case GL_QUERY_BY_REGION_WAIT:
+        case GL_QUERY_BY_REGION_NO_WAIT:
+            inverted = false;
+            break;
+        case GL_QUERY_WAIT_INVERTED:
+        case GL_QUERY_NO_WAIT_INVERTED:
+        case GL_QUERY_BY_REGION_WAIT_INVERTED:
+        case GL_QUERY_BY_REGION_NO_WAIT_INVERTED:
+            inverted = true;
+            break;
+        default:
+            RecordQueryError(ErrorCode::InvalidEnum, __FUNCTION__, "mode is not a conditional render mode.");
+            return;
+        }
+
+        if (MG_State::pGLContext->IsConditionalRenderActive()) {
+            RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__, "Conditional rendering is already active.");
+            return;
+        }
+
+        {
+            const std::lock_guard<std::mutex> lock(g_queryObjectsMutex);
+            const auto* queryObject = FindQueryObjectLocked(id);
+            // A generated NAME is not yet a query object; it becomes one at its first use with a
+            // target (the same rule glIsQuery answers by).
+            if (!queryObject || (!queryObject->created && queryObject->target == 0)) {
+                RecordQueryError(ErrorCode::InvalidValue, __FUNCTION__, "id is not the name of a query object.");
+                return;
+            }
+            if (queryObject->active) {
+                RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__, "The query object is still active.");
+                return;
+            }
+            if (queryObject->target != GL_SAMPLES_PASSED && queryObject->target != GL_ANY_SAMPLES_PASSED &&
+                queryObject->target != GL_ANY_SAMPLES_PASSED_CONSERVATIVE) {
+                RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__,
+                                 "Conditional rendering requires an occlusion query object.");
+                return;
+            }
+        }
+
+        // Resolved ONCE, here, and by WAITING even for the _NO_WAIT modes: the spec lets those
+        // render instead of stalling, so always waiting is conforming and is the only choice that
+        // gives the whole block one deterministic verdict. Reading it per command instead would
+        // let a result that lands mid-block change the answer half way through.
+        Uint64 samplesPassed = 0;
+        if (!GetQueryObjectValue(id, GL_QUERY_RESULT, __FUNCTION__, samplesPassed)) return;
+        const Bool passed = samplesPassed != 0;
+        MG_State::pGLContext->BeginConditionalRender(id, mode, inverted ? passed : !passed);
+    }
+
+    void EndConditionalRender() {
+        if (!MG_State::pGLContext->IsConditionalRenderActive()) {
+            RecordQueryError(ErrorCode::InvalidOperation, __FUNCTION__, "Conditional rendering is not active.");
+            return;
+        }
+        MG_State::pGLContext->EndConditionalRender();
+    }
+
     void GetQueryiv(GLenum target, GLenum pname, GLint* params) {
         if (!params) {
             return;

MobileGL/MG_Impl/GLImpl/Query/GL_Query.h

@@ -29,6 +29,11 @@ namespace MobileGL::MG_Impl::GLImpl {
     void GetQueryBufferObjecti64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
     void GetQueryBufferObjectui64v(GLuint id, GLuint buffer, GLenum pname, GLintptr offset);
     void QueryCounter(GLuint id, GLenum target);
+    // Conditional rendering (GL 4.6 core 10.9). Implemented here rather than beside the drawing
+    // entry points because the predicate is a QUERY OBJECT's result, and the object registry -
+    // with the lock that guards it - lives in this file.
+    void BeginConditionalRender(GLuint id, GLenum mode);
+    void EndConditionalRender();
     // Destroys every still-registered query object exactly as DeleteQueries would.
     // GL requires queries to die with their context; called only from full library
     // teardown (DestroyImpl), where no context survives on any thread, so the

MobileGL/MG_Impl/GLImpl/Sync/GL_Sync.cpp

@@ -8,6 +8,7 @@
 
 #include "GL_Sync.h"
 #include <MG_Backend/BackendObjects.h>
+#include <MG_State/GLState/Core.h>
 
 namespace MobileGL::MG_Impl::GLImpl {
     namespace {
@@ -35,6 +36,22 @@ namespace MobileGL::MG_Impl::GLImpl {
     } // namespace
 
     GLsync FenceSync(GLenum condition, GLbitfield flags) {
+        // GL 4.6 core 4.1.2: GL_SYNC_GPU_COMMANDS_COMPLETE is the only condition and the only
+        // legal flags value is zero; both violations return 0 rather than a handle. A caller that
+        // then hands the 0 back to glDeleteSync hits the glDeleteSync(0) no-op below.
+        if (condition != GL_SYNC_GPU_COMMANDS_COMPLETE) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidEnum,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
+                                             "condition must be GL_SYNC_GPU_COMMANDS_COMPLETE."));
+            return nullptr;
+        }
+        if (flags != 0) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidValue,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__, "flags must be zero."));
+            return nullptr;
+        }
         auto* syncObject = new SyncObject;
         syncObject->condition = condition;
         syncObject->flags = flags;
@@ -64,6 +81,18 @@ namespace MobileGL::MG_Impl::GLImpl {
     }
 
     void WaitSync(GLsync sync, GLbitfield flags, GLuint64 timeout) {
+        // GL 4.6 core 4.1.2: the server-side wait takes no flags and no finite timeout - both
+        // arguments exist only to be forward-compatible, and anything else is INVALID_VALUE.
+        // Neither backend ever honored a nonzero timeout (DirectGLES hard-codes
+        // 0/GL_TIMEOUT_IGNORED, DirectVulkan's queue ordering makes the wait implicit), so
+        // rejecting the call loses no wait that used to happen.
+        if (flags != 0 || timeout != GL_TIMEOUT_IGNORED) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidValue,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
+                                             "flags must be zero and timeout must be GL_TIMEOUT_IGNORED."));
+            return;
+        }
         const auto* syncObject = FindSyncObject(sync);
         if (!syncObject) {
             return;

MobileGL/MG_Impl/GLImpl/Texture/GL_Texture.cpp

@@ -474,15 +474,48 @@ namespace MobileGL::MG_Impl::GLImpl {
                    target == TextureTarget::Texture2DMultisampleArray;
         }
 
-        Int GetMaxSupportedTextureSamples(TextureInternalFormat textureInternalFormat) {
+        // The largest count the backend actually probed for this format on this target, or 0 when
+        // it has no answer for the pair. Both backends build the list in descending order.
+        Int GetProbedMaxTextureSamples(TextureTarget textureTarget, TextureInternalFormat textureInternalFormat) {
+            if (MG_Backend::pActiveBackendObject == nullptr) {
+                return 0;
+            }
+            const SizeT targetIndex = MG_Backend::GetFormatCapabilityTargetIndex(textureTarget);
+            const SizeT formatIndex = static_cast<SizeT>(textureInternalFormat);
+            if (targetIndex >= MG_Backend::kFormatCapabilityTargetCount ||
+                formatIndex >= MG_Backend::kFormatCapabilityFormatCount) {
+                return 0;
+            }
+            const auto& sampleCounts =
+                MG_Backend::pActiveBackendObject->GetFormatCapabilities().SampleCounts[targetIndex][formatIndex];
+            return sampleCounts.empty() ? 0 : sampleCounts.front();
+        }
+
+        // The ceiling the frontend enforces, which must never be lower than the one MobileGL
+        // advertises: the CTS - and real applications - read GL_MAX_SAMPLES once and hand that
+        // exact count to glTexImage*Multisample for every format. Answering 4 there and then
+        // rejecting 4 here because the ES driver reports GL_MAX_INTEGER_SAMPLES 1 (Adreno) is a
+        // self-inconsistency, not a spec-mandated error. The backends clamp the count they hand
+        // the driver; the shadow state keeps reporting what the application asked for.
+        Int GetMaxSupportedTextureSamples(TextureTarget textureTarget,
+                                          TextureInternalFormat textureInternalFormat) {
             if (MG_Backend::pActiveBackendObject == nullptr) {
                 return std::numeric_limits<Int>::max();
             }
 
+            const Int advertisedMaxSamples = GetAdvertisedMaxSamples();
+            // glGetInternalformativ(GL_SAMPLES) is answered from this very list (GetInternalformativ
+            // below), and GL 4.6 core 8.8 makes that query the definition of the per-format
+            // maximum - validating against anything else is how the two answers drifted apart.
+            const Int probedMaxSamples = GetProbedMaxTextureSamples(textureTarget, textureInternalFormat);
+            if (probedMaxSamples > 0) {
+                return std::max(probedMaxSamples, advertisedMaxSamples);
+            }
+
             const auto& dynamicParameters = MG_Backend::pActiveBackendObject->GetDynamicParameters();
             if (MG_Util::IsDepthFormatInternalFormat(textureInternalFormat) ||
                 MG_Util::IsStencilFormatInternalFormat(textureInternalFormat)) {
-                return std::max(dynamicParameters.MaxDepthTextureSamples, 1);
+                return std::max(dynamicParameters.MaxDepthTextureSamples, advertisedMaxSamples);
             }
 
             GLenum normalizedInternalFormat = MG_Util::ConvertTextureInternalFormatToGLEnum(textureInternalFormat);
@@ -495,7 +528,7 @@ namespace MobileGL::MG_Impl::GLImpl {
                                          normalizedFormat == GL_RGB_INTEGER || normalizedFormat == GL_RGBA_INTEGER;
             return std::max(isIntegerFormat ? dynamicParameters.MaxIntegerSamples
                                             : dynamicParameters.MaxColorTextureSamples,
-                            1);
+                            advertisedMaxSamples);
         }
 
         Bool ValidateTextureMultisampleStorage(TextureTarget textureTarget, GLsizei samples, GLsizei width,
@@ -532,7 +565,7 @@ namespace MobileGL::MG_Impl::GLImpl {
             // dimensions, and GL CTS's per-case state reset (gluStateReset) clears the default
             // GL_TEXTURE_2D_MULTISAMPLE_ARRAY texture with glTexImage3DMultisample(..., 0, 0, 0).
 
-            const Int maxSamples = GetMaxSupportedTextureSamples(textureInternalFormat);
+            const Int maxSamples = GetMaxSupportedTextureSamples(textureTarget, textureInternalFormat);
             if (samples > maxSamples) {
                 // GL specifies INVALID_OPERATION - not INVALID_VALUE - when the sample count
                 // exceeds what the format supports, and the native Adreno driver agrees.
@@ -557,6 +590,20 @@ namespace MobileGL::MG_Impl::GLImpl {
                             "AllocateMultisampleTextureStorage requires mipmap-backed storage");
 
             auto* textureMipmapObject = static_cast<MG_State::GLState::TextureObjectMipmap*>(textureObject.get());
+            // GL 4.6 core 8.8: a zero-sized image DEALLOCATES the image rather than defining an
+            // empty one. Only the multisample pair cares, and it cares a great deal: the CTS's
+            // per-case state reset clears both DEFAULT multisample textures this way on every
+            // texture unit, and a "defined" 0x0 default texture stops being skipped by
+            // IsUndefinedDefaultTexture - it then joins the per-draw sync and bind passes on
+            // every unit the reset touched, and reaches an ES glTexStorage*Multisample(..., 0, 0)
+            // that ES 3.1 8.19 makes INVALID_VALUE on every driver there is. A proxy target holds
+            // no image at all, only the query result, so it keeps recording what was asked for.
+            if ((width <= 0 || height <= 0 || depth <= 0) &&
+                !TextureImpl::IsProxyTextureTarget(textureUploadTarget)) {
+                textureObject->SetInternalFormat(TextureInternalFormat::Unknown);
+                textureMipmapObject->TruncateMipmapLevels(textureUploadTarget, 0);
+                return;
+            }
             textureObject->SetInternalFormat(textureInternalFormat);
             textureObject->SetSamples(samples);
             textureObject->SetFixedSampleLocations(fixedsamplelocations == GL_TRUE);
@@ -614,21 +661,42 @@ namespace MobileGL::MG_Impl::GLImpl {
                                              "Compressed texture formats are not supported."));
         }
 
-        // glGetTexLevelParameter{i,f}v answers WIDTH/HEIGHT/DEPTH out of the mipmap chain. The only
-        // other storage type the state layer knows is GL_TEXTURE_BUFFER (TextureStorageType is
-        // {Mipmap, Buffer}), whose level geometry this stack does not track yet. Report that instead
-        // of throwing: THROW_UNIMPL_EXCEPTION unwinds a C++ exception through the C GL ABI and takes
-        // the process down, which is never an acceptable answer to a query - see the same reasoning
-        // above for the compressed-format path.
+        // GL_TEXTURE_WIDTH of a buffer texture: how many texels of the texture's internal format fit
+        // in the buffer range it addresses, CLAMPED to GL_MAX_TEXTURE_BUFFER_SIZE. Attaching a larger
+        // buffer is legal (GL 4.6 core 8.9) - the texture simply addresses the first
+        // MAX_TEXTURE_BUFFER_SIZE texels of it, and that clamped count is what WIDTH reports.
+        //
+        // GL_TEXTURE_BUFFER_SIZE is deliberately NOT clamped the same way: it reports the range in
+        // basic machine units exactly as glTexBuffer/glTexBufferRange were given it. Swapping the two
+        // fails KHR-GL43.texture_buffer.texture_buffer_max_size in the opposite direction.
+        GLint GetBufferTextureTexelWidth(const MG_State::GLState::ITextureObject* textureObject) {
+            const SizeT texelByteSize = MG_Util::GetSizedInternalFormatSizeInBytes(textureObject->GetFormat());
+            // A format with no known footprint has no texel count to report; answering 0 beats
+            // dividing by it.
+            if (texelByteSize == 0) return 0;
+            const auto* bufferTextureObject =
+                static_cast<const MG_State::GLState::TextureObjectBuffer*>(textureObject);
+            const SizeT texelCount = bufferTextureObject->GetBufferRangeSizeInBytes() / texelByteSize;
+            const SizeT maxTexelCount = static_cast<SizeT>(
+                std::max(0, MG_Backend::pActiveBackendObject->GetDynamicParameters().MaxTextureBufferSize));
+            return static_cast<GLint>(std::min(texelCount, maxTexelCount));
+        }
+
+        // glGetTexLevelParameter{i,f}v answers WIDTH/HEIGHT/DEPTH out of the mipmap chain, and (since
+        // the buffer-texture arms above) out of the attached buffer range for GL_TEXTURE_BUFFER. This
+        // is what is left: a storage class with no level geometry at all. Report it instead of
+        // throwing - THROW_UNIMPL_EXCEPTION unwinds a C++ exception through the C GL ABI and takes the
+        // process down, which is never an acceptable answer to a query - see the same reasoning above
+        // for the compressed-format path.
         void RecordUnsupportedLevelQueryStorage(const char* caller, GLenum pname) {
-            MGLOG_W_ONCE("%s: glGetTexLevelParameter(pname=%s) is not implemented for texture-buffer "
-                    "storage; recording GL_INVALID_OPERATION instead of terminating",
+            MGLOG_W_ONCE("%s: glGetTexLevelParameter(pname=%s) is not implemented for this texture's "
+                    "storage class; recording GL_INVALID_OPERATION instead of terminating",
                     caller, MG_Util::ConvertGLEnumToString(pname).c_str());
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidOperation,
                 MakeUnique<GenericErrorInfo>(
                     "MG_Impl/GLImpl", caller,
-                    "Level queries are not supported for texture-buffer storage."));
+                    "Level queries are not supported for this texture's storage class."));
         }
     } // namespace
 
@@ -644,6 +712,34 @@ namespace MobileGL::MG_Impl::GLImpl {
         return textureObject;
     }
 
+    // Whether a raw internalformat enum names a compressed format - the question GL asks whenever an
+    // entry point is forbidden on a compressed image: glTexStorage3D on TEXTURE_3D (no
+    // block-compressed format is defined for a three-dimensional image, so it is INVALID_OPERATION
+    // rather than the INVALID_ENUM an unknown sized format gets - GL 4.6 core 8.19 / Khronos bug
+    // 11239, KHR-GLxx.texture_storage.compressed_data) and the clear-texture pair (8.19 again).
+    // Written against the enum ranges rather than a name list because the families are contiguous
+    // and MobileGL's own internal-format enum drops the ones it cannot carry, which would make this
+    // check silently narrower than the API surface.
+    static Bool IsCompressedGLInternalFormat(GLenum internalformat) {
+        switch (internalformat) {
+        case 0x8225: // GL_COMPRESSED_RED
+        case 0x8226: // GL_COMPRESSED_RG
+        case 0x84ED: // GL_COMPRESSED_RGB
+        case 0x84EE: // GL_COMPRESSED_RGBA
+        case 0x8C48: // GL_COMPRESSED_SRGB
+        case 0x8C49: // GL_COMPRESSED_SRGB_ALPHA
+            return true;
+        default:
+            break;
+        }
+        return (internalformat >= 0x83F0 && internalformat <= 0x83F3) || // S3TC / DXT
+               (internalformat >= 0x8DBB && internalformat <= 0x8DBE) || // RGTC
+               (internalformat >= 0x8E8C && internalformat <= 0x8E8F) || // BPTC
+               (internalformat >= 0x9270 && internalformat <= 0x9279) || // ETC2 / EAC
+               (internalformat >= 0x93B0 && internalformat <= 0x93BD) || // ASTC LDR
+               (internalformat >= 0x93D0 && internalformat <= 0x93DD);   // ASTC sRGB
+    }
+
     namespace {
         void RecordClearTextureError(const char* caller, ErrorCode code, const String& message) {
             MG_State::pGLContext->RecordError(
@@ -679,6 +775,21 @@ namespace MobileGL::MG_Impl::GLImpl {
                                         std::format("Texture level {} is not defined.", level));
                 return nullptr;
             }
+            // GL 4.6 core 8.19: a compressed internal format is INVALID_OPERATION for both clear
+            // entry points. Two tags to ask, because they answer different questions: the stored
+            // one covers a level glCompressedTexImage* or a SPECIFIC compressed internalformat
+            // defined, the requested one covers the six generic GL_COMPRESSED_* enums that MobileGL
+            // deliberately backs with uncompressed storage (see MipmapStorage) and that would
+            // otherwise look like an ordinary RGBA8 image by the time the clear runs.
+            const auto& uploadTargets = mipmapTexture->GetUploadTargets();
+            if (!uploadTargets.empty() &&
+                (mipmapTexture->GetMipmapCompressedFormat(uploadTargets[0], static_cast<Uint>(level)) != GL_NONE ||
+                 mipmapTexture->GetMipmapRequestedCompressedFormat(uploadTargets[0], static_cast<Uint>(level)) !=
+                     GL_NONE)) {
+                RecordClearTextureError(caller, ErrorCode::InvalidOperation,
+                                        "Compressed textures cannot be cleared.");
+                return nullptr;
+            }
             return mipmapTexture;
         }
 
@@ -2150,6 +2261,26 @@ namespace MobileGL::MG_Impl::GLImpl {
         } else {
             DiscardMipmapChainOnBaseRespecification(textureMipmapObject, textureUploadTarget, level);
             textureMipmapObject->AllocateStorage(textureUploadTarget, level, {{width, height, depth}, internalBytes});
+            // The same specific-compressed-format tag glTexImage2D records (see TexImage2D_State):
+            // GL 4.6 core 8.5 commits the level to that format, so GL_TEXTURE_COMPRESSED and
+            // GL_TEXTURE_INTERNAL_FORMAT must report it - and, less obviously, glCopyImageSubData
+            // sizes the level's texel BLOCK from it. Without the tag a GL_COMPRESSED_RG_RGTC2
+            // array level measured as the RG8 storage it resolved to, 2 bytes instead of 16, and
+            // the copy-compatibility rule refused a pairing 18.3.2 requires. AllocateStorage above
+            // clears the tag, so this has to follow it.
+            const auto compressedInfo = MG_Util::GetCompressedFormatInfo(static_cast<GLenum>(internalformat));
+            if (compressedInfo.blockWidth != 0) {
+                textureMipmapObject->SetMipmapCompressedImage(
+                    textureUploadTarget, level, static_cast<GLenum>(internalformat), nullptr,
+                    MG_Util::CalculateCompressedTextureImageSize(compressedInfo, {width, height, depth}));
+            }
+            // Also after AllocateStorage, which clears it. Records the generic GL_COMPRESSED_*
+            // enums too, which the tag above deliberately skips - glClearTexImage has to refuse
+            // them all (GL 4.6 core 8.19).
+            if (IsCompressedGLInternalFormat(static_cast<GLenum>(internalformat))) {
+                textureMipmapObject->SetMipmapRequestedCompressedFormat(textureUploadTarget, level,
+                                                                        static_cast<GLenum>(internalformat));
+            }
         }
 
         if (!originalPixels) {
@@ -2296,6 +2427,13 @@ namespace MobileGL::MG_Impl::GLImpl {
                     textureUploadTarget, level, static_cast<GLenum>(internalformat), nullptr,
                     MG_Util::CalculateCompressedTextureImageSize(compressedInfo, {width, height, 1}));
             }
+            // Also after AllocateStorage, which clears it. Records the generic GL_COMPRESSED_*
+            // enums too, which the tag above deliberately skips - glClearTexImage has to refuse
+            // them all (GL 4.6 core 8.19).
+            if (IsCompressedGLInternalFormat(static_cast<GLenum>(internalformat))) {
+                textureMipmapObject->SetMipmapRequestedCompressedFormat(textureUploadTarget, level,
+                                                                        static_cast<GLenum>(internalformat));
+            }
         }
 
         if (!originalPixels) {
@@ -2384,6 +2522,13 @@ namespace MobileGL::MG_Impl::GLImpl {
         if (!isProxy) {
             DiscardMipmapChainOnBaseRespecification(textureMipmapObject, textureUploadTarget, level);
             textureMipmapObject->AllocateStorage(textureUploadTarget, level, {{width, 1, 1}, internalBytes});
+            // After AllocateStorage, which clears the tag. No block-compressed format has a 1D
+            // layout, so only the specific-format tag the 2D/3D paths record is skipped here - the
+            // request itself still has to be remembered for glClearTexImage (GL 4.6 core 8.19).
+            if (IsCompressedGLInternalFormat(static_cast<GLenum>(internalFormat))) {
+                textureMipmapObject->SetMipmapRequestedCompressedFormat(textureUploadTarget, level,
+                                                                        static_cast<GLenum>(internalFormat));
+            }
         }
 
         if (!originalPixels) {
@@ -2935,6 +3080,15 @@ namespace MobileGL::MG_Impl::GLImpl {
                 *params = textureObject->GetSamplerObject()->GetMaxAnisotropy();
             }
             break;
+        // GL 4.6 core 8.11 lists this among the parameters EVERY GetTexParameter form answers.
+        // It was handled by the iv/Iiv/Iuiv getters and missed by this one, so the float query
+        // raised GL_INVALID_ENUM and left the caller's float untouched - which is what
+        // KHR-GL4x.shader_image_load_store.basic-api-texParam reads back.
+        case GL_IMAGE_FORMAT_COMPATIBILITY_TYPE:
+            if (params) {
+                *params = static_cast<GLfloat>(GL_IMAGE_FORMAT_COMPATIBILITY_BY_SIZE);
+            }
+            break;
         case GL_DEPTH_STENCIL_TEXTURE_MODE:
             if (params) {
                 *params = static_cast<GLfloat>(textureObject->GetDepthStencilTextureMode());
@@ -2984,6 +3138,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                     *params = textureMipmapObject->GetMipmapTexelSize(textureUploadTarget, level).x();
                     break;
                 }
+                case TextureStorageType::Buffer:
+                    *params = GetBufferTextureTexelWidth(textureObject.get());
+                    break;
                 default:
                     RecordUnsupportedLevelQueryStorage("GetTexLevelParameteriv_State", pname);
                     break;
@@ -2999,6 +3156,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                     *params = textureMipmapObject->GetMipmapTexelSize(textureUploadTarget, level).y();
                     break;
                 }
+                case TextureStorageType::Buffer:
+                    *params = 1; // a buffer texture is one-dimensional
+                    break;
                 default:
                     RecordUnsupportedLevelQueryStorage("GetTexLevelParameteriv_State", pname);
                     break;
@@ -3014,6 +3174,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                     *params = textureMipmapObject->GetMipmapTexelSize(textureUploadTarget, level).z();
                     break;
                 }
+                case TextureStorageType::Buffer:
+                    *params = 1; // a buffer texture is one-dimensional
+                    break;
                 default:
                     RecordUnsupportedLevelQueryStorage("GetTexLevelParameteriv_State", pname);
                     break;
@@ -3083,6 +3246,31 @@ namespace MobileGL::MG_Impl::GLImpl {
             }
             break;
         }
+        case GL_TEXTURE_BUFFER_SIZE:
+        case GL_TEXTURE_BUFFER_OFFSET: {
+            // GL 4.6 core 8.9: both describe the window of the attached buffer a GL_TEXTURE_BUFFER
+            // texture addresses, so there is nothing to report for any other storage - which is
+            // INVALID_OPERATION, the same shape GL_TEXTURE_COMPRESSED_IMAGE_SIZE guards itself with
+            // above.
+            if (textureObject->GetStorageType() != TextureStorageType::Buffer) {
+                MG_State::pGLContext->RecordError(
+                    ErrorCode::InvalidOperation,
+                    MakeUnique<GenericErrorInfo>(
+                        "MG_Impl/GLImpl", "GetTexLevelParameteriv_State",
+                        "GL_TEXTURE_BUFFER_SIZE / GL_TEXTURE_BUFFER_OFFSET need a buffer texture."));
+                return;
+            }
+            if (params) {
+                const auto* bufferTextureObject =
+                    static_cast<MG_State::GLState::TextureObjectBuffer*>(textureObject.get());
+                // Basic machine units, and UNCLAMPED - see GetBufferTextureTexelWidth for why this
+                // half does not take the GL_MAX_TEXTURE_BUFFER_SIZE clamp that WIDTH does.
+                *params = static_cast<GLint>(pname == GL_TEXTURE_BUFFER_SIZE
+                                                 ? bufferTextureObject->GetBufferRangeSizeInBytes()
+                                                 : bufferTextureObject->GetBufferRangeOffset());
+            }
+            break;
+        }
         default:
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidEnum, MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", "GetTexLevelParameteriv_State",
@@ -3122,6 +3310,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                     *params = (GLfloat)textureMipmapObject->GetMipmapTexelSize(textureUploadTarget, level).x();
                     break;
                 }
+                case TextureStorageType::Buffer:
+                    *params = (GLfloat)GetBufferTextureTexelWidth(textureObject.get());
+                    break;
                 default:
                     RecordUnsupportedLevelQueryStorage("GetTexLevelParameterfv_State", pname);
                     break;
@@ -3137,6 +3328,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                     *params = (GLfloat)textureMipmapObject->GetMipmapTexelSize(textureUploadTarget, level).y();
                     break;
                 }
+                case TextureStorageType::Buffer:
+                    *params = 1.0f; // a buffer texture is one-dimensional
+                    break;
                 default:
                     RecordUnsupportedLevelQueryStorage("GetTexLevelParameterfv_State", pname);
                     break;
@@ -3152,6 +3346,9 @@ namespace MobileGL::MG_Impl::GLImpl {
                     *params = (GLfloat)textureMipmapObject->GetMipmapTexelSize(textureUploadTarget, level).z();
                     break;
                 }
+                case TextureStorageType::Buffer:
+                    *params = 1.0f; // a buffer texture is one-dimensional
+                    break;
                 default:
                     RecordUnsupportedLevelQueryStorage("GetTexLevelParameterfv_State", pname);
                     break;
@@ -3219,6 +3416,27 @@ namespace MobileGL::MG_Impl::GLImpl {
             }
             break;
         }
+        case GL_TEXTURE_BUFFER_SIZE:
+        case GL_TEXTURE_BUFFER_OFFSET: {
+            // See GetTexLevelParameteriv_State: both describe the attached buffer range of a
+            // GL_TEXTURE_BUFFER texture, so any other storage makes the query INVALID_OPERATION.
+            if (textureObject->GetStorageType() != TextureStorageType::Buffer) {
+                MG_State::pGLContext->RecordError(
+                    ErrorCode::InvalidOperation,
+                    MakeUnique<GenericErrorInfo>(
+                        "MG_Impl/GLImpl", "GetTexLevelParameterfv_State",
+                        "GL_TEXTURE_BUFFER_SIZE / GL_TEXTURE_BUFFER_OFFSET need a buffer texture."));
+                return;
+            }
+            if (params) {
+                const auto* bufferTextureObject =
+                    static_cast<MG_State::GLState::TextureObjectBuffer*>(textureObject.get());
+                *params = static_cast<GLfloat>(pname == GL_TEXTURE_BUFFER_SIZE
+                                                   ? bufferTextureObject->GetBufferRangeSizeInBytes()
+                                                   : bufferTextureObject->GetBufferRangeOffset());
+            }
+            break;
+        }
         default:
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidEnum, MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", "GetTexLevelParameterfv_State",
@@ -3365,9 +3583,9 @@ namespace MobileGL::MG_Impl::GLImpl {
         MG_Backend::gBackendFunctionsTable.GL.CopyTexSubImage2D(target, level, xoffset, yoffset, x, y, width, height);
     }
 
-    void CopyImageSubData_Backend(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
+    void CopyImageSubData_Backend(const MG_Backend::CopyImageEndpoint& src,
                                   GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                                  const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
+                                  const MG_Backend::CopyImageEndpoint& dst,
                                   GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                                   GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
         auto copyImageSubData = MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData;
@@ -3378,7 +3596,7 @@ namespace MobileGL::MG_Impl::GLImpl {
                                              "Backend does not support image-to-image copies."));
             return;
         }
-        copyImageSubData(srcTexture, srcTarget, srcLevel, srcX, srcY, srcZ, dstTexture, dstTarget, dstLevel, dstX,
+        copyImageSubData(src, srcTarget, srcLevel, srcX, srcY, srcZ, dst, dstTarget, dstLevel, dstX,
                          dstY, dstZ, srcWidth, srcHeight, srcDepth);
     }
 
@@ -3425,9 +3643,9 @@ namespace MobileGL::MG_Impl::GLImpl {
         // the ~30 entry points that reach it through a BOUND object (where the name was never
         // in question and the fault is the binding), so this is a local rule rather than a
         // change to the helper.
-        Bool ValidateCopyImageObjectExists(const SharedPtr<MG_State::GLState::ITextureObject>& textureObject,
+        Bool ValidateCopyImageObjectExists(const MG_Backend::CopyImageEndpoint& endpoint,
                                            const char* endpointName) {
-            if (textureObject) return true;
+            if (endpoint.Exists()) return true;
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidValue,
                 MakeUnique<GenericErrorInfo>(
@@ -3451,21 +3669,151 @@ namespace MobileGL::MG_Impl::GLImpl {
                                 MG_Util::ConvertTextureTargetToString(textureObject->GetTarget()))));
             return false;
         }
-    } // namespace
 
-    Bool ValidateCopyImageSubData_State(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture,
-                                        GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY,
-                                        const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture,
-                                        GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY,
-                                        GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
-        if (!ValidateCopyImageObjectExists(srcTexture, "source") ||
-            !ValidateCopyImageObjectExists(dstTexture, "destination")) {
+        // ---- The questions ValidateCopyImageSubData_State asks of one endpoint. ---------------
+        // A renderbuffer answers all of them directly: it has exactly one image, no mip chain and
+        // no sampler state, and it carries its own internal format and extent.
+
+        Int GetCopyImageEndpointSamples(const MG_Backend::CopyImageEndpoint& endpoint) {
+            if (endpoint.IsRenderbuffer()) return endpoint.Renderbuffer->GetSamples();
+            return endpoint.Texture->GetSamples();
+        }
+
+        TextureInternalFormat GetCopyImageEndpointFormat(const MG_Backend::CopyImageEndpoint& endpoint) {
+            if (endpoint.IsRenderbuffer()) return endpoint.Renderbuffer->GetInternalFormat();
+            return endpoint.Texture->GetFormat();
+        }
+
+        // A renderbuffer has level 0 and nothing else, and the failure is the same INVALID_VALUE
+        // ValidateTextureLevelExists records for a level a texture does not have.
+        Bool ValidateCopyImageEndpointLevelExists(const MG_Backend::CopyImageEndpoint& endpoint, GLint level,
+                                                  const char* caller) {
+            if (!endpoint.IsRenderbuffer()) {
+                return TextureImpl::ValidateTextureLevelExists(endpoint.Texture, level, caller);
+            }
+            if (level == 0) return true;
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidValue,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller, "A renderbuffer has only level 0."));
             return false;
         }
-        const auto srcTextureTarget = MG_Util::ConvertGLEnumToTextureTarget(srcTarget);
-        const auto dstTextureTarget = MG_Util::ConvertGLEnumToTextureTarget(dstTarget);
-        if (!TextureImpl::ValidateTextureTarget(srcTextureTarget) ||
-            !TextureImpl::ValidateTextureTarget(dstTextureTarget)) {
+
+        // Targets with no mip chain have q == level_base by definition (GL 4.6 core 8.17), so no
+        // minification filter can make them mipmap incomplete - while the shared predicate derives
+        // q from the base level's size alone and would call a 16x16 multisample image incomplete.
+        Bool CopyImageTargetHasMipmapChain(TextureTarget target) {
+            switch (target) {
+            case TextureTarget::TextureRectangle:
+            case TextureTarget::TextureBuffer:
+            case TextureTarget::Texture2DMultisample:
+            case TextureTarget::Texture2DMultisampleArray:
+                return false;
+            default:
+                return true;
+            }
+        }
+
+        Bool IsCopyImageEndpointComplete(const MG_Backend::CopyImageEndpoint& endpoint) {
+            // A renderbuffer is complete exactly when it has storage - there is nothing else it
+            // could be missing.
+            if (endpoint.IsRenderbuffer()) return endpoint.Renderbuffer->IsAllocated();
+            const auto* texture = endpoint.Texture.get();
+            if (!texture) return false;
+            // 18.3.2 asks for TEXTURE completeness, which GL 4.6 core 8.17 defines to include the
+            // MIP CHAIN whenever the minification filter samples it - and ITextureObject::
+            // IsComplete() only answers the storage half (an internal format, and no zero-size
+            // level in the middle of the chain). A texture with level 0 alone and the default
+            // NEAREST_MIPMAP_LINEAR filter is incomplete, which is exactly how
+            // KHR-GL43.copy_image.incomplete_tex builds its subject.
+            //
+            // The filter is the texture's OWN: copy-image never goes through a texture unit, so no
+            // sampler object is in play. An immutable texture is unaffected - glTexStorage clamps
+            // TEXTURE_MAX_LEVEL to levels-1, which is what makes a single-level immutable texture
+            // mipmap complete under any filter.
+            const auto& sampler = texture->GetSamplerObject();
+            const Bool mipmapped = CopyImageTargetHasMipmapChain(texture->GetTarget()) && sampler &&
+                                   sampler->GetMipmapMode() != SamplerMipmapMode::None;
+            return MG_State::GLState::IsMipmapCompleteForFilter(texture, mipmapped);
+        }
+
+        GLenum GetCopyImageEndpointCompressedFormat(const MG_Backend::CopyImageEndpoint& endpoint,
+                                                    TextureUploadTarget uploadTarget, GLint level) {
+            if (endpoint.IsRenderbuffer()) return GL_NONE;
+            return GetCompressedLevelFormat(endpoint.Texture, uploadTarget, level);
+        }
+
+        IntVec3 GetCopyImageEndpointLevelSize(const MG_Backend::CopyImageEndpoint& endpoint,
+                                              TextureUploadTarget uploadTarget, GLint level) {
+            if (endpoint.IsRenderbuffer()) {
+                return {endpoint.Renderbuffer->GetWidth(), endpoint.Renderbuffer->GetHeight(), 1};
+            }
+            return GetCopyImageLevelSize(endpoint.Texture, uploadTarget, level);
+        }
+
+        // How far the region's z axis may reach. It does not mean the same thing on every target
+        // GL 4.6 core 18.3.2 accepts: on a CUBE MAP it selects among the six faces, which this
+        // frontend keeps as six separate one-slice upload targets - so the level's own extent
+        // says 1 and the real bound is 6. A cube-map ARRAY is one upload target whose depth
+        // already counts layer-faces, and a 1D array carries its layers on y (which is where GL
+        // puts them for this entry point too), so both are answered by the level extent.
+        Int GetCopyImageEndpointLayerCount(const MG_Backend::CopyImageEndpoint& endpoint,
+                                           const IntVec3& levelSize) {
+            if (!endpoint.IsRenderbuffer() && endpoint.Texture &&
+                endpoint.Texture->GetTarget() == TextureTarget::TextureCubeMap) {
+                return 6;
+            }
+            return std::max(levelSize.z(), 1);
+        }
+
+        // GL 4.6 core 18.3.2 requires INVALID_VALUE when the region exceeds either image's
+        // boundaries. The only bounds-shaped call this validator used to make was
+        // ValidateCopyImageBlockAlignment, whose first line returns true for every UNCOMPRESSED
+        // format - so no uncompressed copy was bounded at all, and the z extent could not be
+        // bounded even in principle because srcZ/dstZ never reached the validator. Texture
+        // endpoints were covered only by accident, through the ES driver's own error, which the
+        // DirectGLES backend logs and swallows rather than reporting; a GL_RENDERBUFFER endpoint
+        // got neither (KHR-GL43.copy_image.exceeding_boundaries).
+        Bool ValidateCopyImageRegionBounds(const MG_Backend::CopyImageEndpoint& endpoint, const IntVec3& levelSize,
+                                           GLint x, GLint y, GLint z, GLsizei width, GLsizei height, GLsizei depth,
+                                           const char* endpointName) {
+            // An extent this frontend does not know cannot bound anything, and guessing would
+            // reject a copy GL allows. Every caller has already established that the level
+            // exists and that the image is complete, so this is a belt-and-braces guard.
+            if (levelSize.x() <= 0 || levelSize.y() <= 0) return true;
+            const Int layers = GetCopyImageEndpointLayerCount(endpoint, levelSize);
+            if (x >= 0 && y >= 0 && z >= 0 && static_cast<Int64>(x) + width <= levelSize.x() &&
+                static_cast<Int64>(y) + height <= levelSize.y() && static_cast<Int64>(z) + depth <= layers) {
+                return true;
+            }
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidValue,
+                MakeUnique<GenericErrorInfo>(
+                    "MG_Impl/GLImpl", "ValidateCopyImageSubData_State",
+                    std::format("The {} region [{}, {}, {}] + [{} x {} x {}] does not fit inside the {} x {} x {} "
+                                "image.",
+                                endpointName, x, y, z, width, height, depth, levelSize.x(), levelSize.y(), layers)));
+            return false;
+        }
+    } // namespace
+
+    Bool ValidateCopyImageSubData_State(const MG_Backend::CopyImageEndpoint& src,
+                                        GLenum srcTarget, GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
+                                        const MG_Backend::CopyImageEndpoint& dst,
+                                        GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
+                                        GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
+        if (!ValidateCopyImageObjectExists(src, "source") ||
+            !ValidateCopyImageObjectExists(dst, "destination")) {
+            return false;
+        }
+        // GL_RENDERBUFFER has no TextureTarget to convert to, and it needs none: it is its own
+        // whole-image target, and the endpoint that carries it was resolved from the renderbuffer
+        // namespace, so it matches its object by construction.
+        const auto srcTextureTarget =
+            src.IsRenderbuffer() ? TextureTarget::Unknown : MG_Util::ConvertGLEnumToTextureTarget(srcTarget);
+        const auto dstTextureTarget =
+            dst.IsRenderbuffer() ? TextureTarget::Unknown : MG_Util::ConvertGLEnumToTextureTarget(dstTarget);
+        if ((!src.IsRenderbuffer() && !TextureImpl::ValidateTextureTarget(srcTextureTarget)) ||
+            (!dst.IsRenderbuffer() && !TextureImpl::ValidateTextureTarget(dstTextureTarget))) {
             return false;
         }
         // GL_TEXTURE_BUFFER and the cube FACE enums convert to a target this frontend knows, but
@@ -3473,8 +3821,8 @@ namespace MobileGL::MG_Impl::GLImpl {
         if (!ValidateCopyImageTarget(srcTarget, "source") || !ValidateCopyImageTarget(dstTarget, "destination")) {
             return false;
         }
-        if (!ValidateCopyImageTargetMatchesObject(srcTexture, srcTextureTarget, "source") ||
-            !ValidateCopyImageTargetMatchesObject(dstTexture, dstTextureTarget, "destination")) {
+        if (!ValidateCopyImageTargetMatchesObject(src.Texture, srcTextureTarget, "source") ||
+            !ValidateCopyImageTargetMatchesObject(dst.Texture, dstTextureTarget, "destination")) {
             return false;
         }
         if (!TextureImpl::ValidateTextureLevelNumber(srcLevel) ||
@@ -3488,8 +3836,8 @@ namespace MobileGL::MG_Impl::GLImpl {
         // driver as an out-of-range mip index - on Adreno that is a SIGSEGV inside
         // vkCmdCopyImage, which is what KHR-GL43.copy_image.non_existent_mipmap used to do to
         // the whole glcts process. The answer the spec asks for is GL_INVALID_VALUE.
-        if (!TextureImpl::ValidateTextureLevelExists(srcTexture, srcLevel, __func__) ||
-            !TextureImpl::ValidateTextureLevelExists(dstTexture, dstLevel, __func__)) {
+        if (!ValidateCopyImageEndpointLevelExists(src, srcLevel, __func__) ||
+            !ValidateCopyImageEndpointLevelExists(dst, dstLevel, __func__)) {
             return false;
         }
         if (srcWidth < 0 || srcHeight < 0 || srcDepth < 0) {
@@ -3505,43 +3853,55 @@ namespace MobileGL::MG_Impl::GLImpl {
         // A multisample image can only be copied to one with the same sample count, and a
         // single-sample image reports zero - so this one comparison is also what rejects
         // copying between a multisample target and a non-multisample one.
-        if (srcTexture->GetSamples() != dstTexture->GetSamples()) {
+        const Int srcSamples = GetCopyImageEndpointSamples(src);
+        const Int dstSamples = GetCopyImageEndpointSamples(dst);
+        if (srcSamples != dstSamples) {
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidOperation,
                 MakeUnique<GenericErrorInfo>(
                     "MG_Impl/GLImpl", __func__,
                     std::format("The two images have different sample counts ({} vs. {}).",
-                                srcTexture->GetSamples(), dstTexture->GetSamples())));
+                                srcSamples, dstSamples)));
             return false;
         }
         // 18.3.2: both images must be complete. An incomplete one has no defined texels to copy
         // and no defined storage to copy into.
-        if (!srcTexture->IsComplete() || !dstTexture->IsComplete()) {
+        const Bool srcComplete = IsCopyImageEndpointComplete(src);
+        const Bool dstComplete = IsCopyImageEndpointComplete(dst);
+        if (!srcComplete || !dstComplete) {
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidOperation,
                 MakeUnique<GenericErrorInfo>(
                     "MG_Impl/GLImpl", __func__,
                     std::format("A copied image is incomplete (source complete: {}, destination complete: {}).",
-                                srcTexture->IsComplete(), dstTexture->IsComplete())));
+                                srcComplete, dstComplete)));
             return false;
         }
-        const auto srcUploadTarget = GetPrimaryUploadTarget(srcTexture);
-        const auto dstUploadTarget = GetPrimaryUploadTarget(dstTexture);
+        const auto srcUploadTarget = GetPrimaryUploadTarget(src.Texture);
+        const auto dstUploadTarget = GetPrimaryUploadTarget(dst.Texture);
         const auto srcBlock = TextureImpl::ResolveCopyImageTexelBlock(
-            srcTexture->GetFormat(), GetCompressedLevelFormat(srcTexture, srcUploadTarget, srcLevel));
+            GetCopyImageEndpointFormat(src), GetCopyImageEndpointCompressedFormat(src, srcUploadTarget, srcLevel));
         const auto dstBlock = TextureImpl::ResolveCopyImageTexelBlock(
-            dstTexture->GetFormat(), GetCompressedLevelFormat(dstTexture, dstUploadTarget, dstLevel));
+            GetCopyImageEndpointFormat(dst), GetCopyImageEndpointCompressedFormat(dst, dstUploadTarget, dstLevel));
         if (!TextureImpl::ValidateCopyImageFormatCompatibility(srcBlock, dstBlock)) {
             return false;
         }
-        const IntVec3 srcLevelSize = GetCopyImageLevelSize(srcTexture, srcUploadTarget, srcLevel);
-        const IntVec3 dstLevelSize = GetCopyImageLevelSize(dstTexture, dstUploadTarget, dstLevel);
+        const IntVec3 srcLevelSize = GetCopyImageEndpointLevelSize(src, srcUploadTarget, srcLevel);
+        const IntVec3 dstLevelSize = GetCopyImageEndpointLevelSize(dst, dstUploadTarget, dstLevel);
         if (!TextureImpl::ValidateCopyImageBlockAlignment(srcBlock, srcX, srcY, srcWidth, srcHeight,
                                                           srcLevelSize.x(), srcLevelSize.y(), "source") ||
             !TextureImpl::ValidateCopyImageBlockAlignment(dstBlock, dstX, dstY, srcWidth, srcHeight,
                                                           dstLevelSize.x(), dstLevelSize.y(), "destination")) {
             return false;
         }
+        // One region extent, measured against both images: GL 4.6 core 18.3.2 gives the copy a
+        // single width/height/depth and requires it to fit in the source AND the destination.
+        if (!ValidateCopyImageRegionBounds(src, srcLevelSize, srcX, srcY, srcZ, srcWidth, srcHeight, srcDepth,
+                                           "source") ||
+            !ValidateCopyImageRegionBounds(dst, dstLevelSize, dstX, dstY, dstZ, srcWidth, srcHeight, srcDepth,
+                                           "destination")) {
+            return false;
+        }
         return true;
     }
 
@@ -4051,8 +4411,14 @@ namespace MobileGL::MG_Impl::GLImpl {
             return false;
         }
 
-        // For a cube map this is exactly cube completeness: IsComplete() wants all six faces.
-        if (!textureObject->IsComplete()) {
+        // GL 4.6 core 8.11.4 names cube completeness as the only completeness a readback requires,
+        // and for a cube map that is exactly what IsComplete() answers (all six faces defined at
+        // every level). It must not speak for any other target: on a mip chain it also rejects
+        // "level N defined, the levels below it not", which is a perfectly readable texture at
+        // level N - and the shape glClearTexImage's conformance cases build, since they define
+        // only the level they clear. The requested level's own existence is checked below.
+        if ((target == TextureTarget::TextureCubeMap || target == TextureTarget::TextureCubeMapArray) &&
+            !textureObject->IsComplete()) {
             MG_State::pGLContext->RecordError(
                 ErrorCode::InvalidOperation,
                 MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller, "Texture is incomplete"));
@@ -4084,8 +4450,8 @@ namespace MobileGL::MG_Impl::GLImpl {
         }
 
         // Shared format/type/internal-format matrix (packed-type pairing, depth-vs-color mismatch,
-        // integer-ness). Also rejects STENCIL_INDEX readback, which needs GL_ARB_texture_stencil8
-        // (not advertised by MobileGL).
+        // integer-ness). Also rejects a STENCIL_INDEX readback of anything but stencil-only
+        // storage, which is the only pairing GL 4.4 / ARB_texture_stencil8 ever made legal.
         if (!TextureImpl::ValidateTextureInternalFormatCompatibleWithInput(
                 textureInputFormat, textureObject->GetFormat(), texturePixelDataType)) {
             return false;
@@ -4111,33 +4477,48 @@ namespace MobileGL::MG_Impl::GLImpl {
             const auto* textureMipmapObject =
                 static_cast<const MG_State::GLState::TextureObjectMipmap*>(textureObject.get());
             const auto& uploadTargets = textureObject->GetUploadTargets();
-            if (!uploadTargets.empty() && static_cast<Uint>(level) < textureMipmapObject->GetMipmapLevelCount()) {
-                // Tightly packed, and summed over every face because a cube map query returns all
-                // six. Pack pixel-store state only ever grows this, so a request rejected here
-                // could not have fit under any packing.
-                const auto texelSize = textureMipmapObject->GetMipmapTexelSize(uploadTargets[0], level);
-                const SizeT required = MG_Util::CalculateInputTextureImageSize(textureInputFormat,
-                                                                               texturePixelDataType, texelSize) *
-                                       uploadTargets.size();
+            // The half of the completeness gate above that GL does keep: the REQUESTED level has
+            // to hold an image. A name that was never given one carries no levels at all (which is
+            // also what an Unknown internal format answers), and a chain grown to reach level N
+            // leaves every level below it at {0, 0, 0}.
+            if (uploadTargets.empty() || static_cast<Uint>(level) >= textureMipmapObject->GetMipmapLevelCount()) {
+                MG_State::pGLContext->RecordError(
+                    ErrorCode::InvalidOperation,
+                    MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller, "Texture level has no image to read back."));
+                return false;
+            }
+            const auto texelSize = textureMipmapObject->GetMipmapTexelSize(uploadTargets[0], level);
+            if (texelSize.x() <= 0 || texelSize.y() <= 0 || texelSize.z() <= 0) {
+                MG_State::pGLContext->RecordError(
+                    ErrorCode::InvalidOperation,
+                    MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller, "Texture level has no image to read back."));
+                return false;
+            }
 
-                if (bufSize >= 0 && static_cast<SizeT>(bufSize) < required) {
+            // Tightly packed, and summed over every face because a cube map query returns all
+            // six. Pack pixel-store state only ever grows this, so a request rejected here
+            // could not have fit under any packing.
+            const SizeT required = MG_Util::CalculateInputTextureImageSize(textureInputFormat,
+                                                                           texturePixelDataType, texelSize) *
+                                   uploadTargets.size();
+
+            if (bufSize >= 0 && static_cast<SizeT>(bufSize) < required) {
+                MG_State::pGLContext->RecordError(
+                    ErrorCode::InvalidOperation,
+                    MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller, "Destination buffer is too small."));
+                return false;
+            }
+
+            if (pixelPackBufferObject) {
+                const SizeT bufferSize = pixelPackBufferObject->GetSize();
+                const SizeT offset = reinterpret_cast<SizeT>(pixels);
+                if (offset > bufferSize || required > bufferSize - offset) {
                     MG_State::pGLContext->RecordError(
                         ErrorCode::InvalidOperation,
-                        MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller, "Destination buffer is too small."));
+                        MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller,
+                                                     "Packing would write past the end of the pixel pack buffer."));
                     return false;
                 }
-
-                if (pixelPackBufferObject) {
-                    const SizeT bufferSize = pixelPackBufferObject->GetSize();
-                    const SizeT offset = reinterpret_cast<SizeT>(pixels);
-                    if (offset > bufferSize || required > bufferSize - offset) {
-                        MG_State::pGLContext->RecordError(
-                            ErrorCode::InvalidOperation,
-                            MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller,
-                                                         "Packing would write past the end of the pixel pack buffer."));
-                        return false;
-                    }
-                }
             }
         }
 
@@ -4372,6 +4753,12 @@ namespace MobileGL::MG_Impl::GLImpl {
             const SizeT byteSize = ComputeTextureStorageByteSize(textureInternalFormat, levelWidth, 1, 1);
             textureMipmapObject->AllocateStorage(textureUploadTarget, level, {{levelWidth, 1, 1}, byteSize});
             textureMipmapObject->MarkStorageDirty(textureUploadTarget, level, false);
+            if (IsCompressedGLInternalFormat(internalformat)) {
+                // After AllocateStorage, which clears the tag. See TexImage1D_State: no compressed
+                // format has a 1D block layout, but glClearTexImage still has to refuse the request.
+                textureMipmapObject->SetMipmapRequestedCompressedFormat(textureUploadTarget,
+                                                                        static_cast<Uint>(level), internalformat);
+            }
         }
         // Immutable storage defines exactly `levels` levels; AllocateStorage only grows, so a
         // longer pre-existing chain has to be dropped explicitly.
@@ -4440,6 +4827,12 @@ namespace MobileGL::MG_Impl::GLImpl {
                         MG_Util::CalculateCompressedTextureImageSize(compressedInfo,
                                                                      {levelWidth, levelHeight, 1}));
                 }
+                if (IsCompressedGLInternalFormat(internalformat)) {
+                    // Also after AllocateStorage. The generic enums land here and nowhere above,
+                    // and glClearTexImage has to refuse them too (GL 4.6 core 8.19).
+                    textureMipmapObject->SetMipmapRequestedCompressedFormat(uploadTarget,
+                                                                            static_cast<Uint>(level), internalformat);
+                }
             }
             // See TextureStorage1D.
             textureMipmapObject->TruncateMipmapLevels(uploadTarget, static_cast<Uint>(levels));
@@ -4447,32 +4840,6 @@ namespace MobileGL::MG_Impl::GLImpl {
         textureObject->SetImmutableLevels(static_cast<Uint>(levels));
     }
 
-    // No block-compressed format is defined for a three-dimensional image, so glTexStorage3D on
-    // TEXTURE_3D must reject one - and with INVALID_OPERATION, not the INVALID_ENUM an unknown
-    // sized format gets (GL 4.6 core 8.19 / Khronos bug 11239, KHR-GLxx.texture_storage
-    // .compressed_data). Written against the enum ranges rather than a name list because the
-    // families are contiguous and MobileGL's own internal-format enum drops the ones it cannot
-    // carry, which would make this check silently narrower than the API surface.
-    static Bool IsCompressedGLInternalFormat(GLenum internalformat) {
-        switch (internalformat) {
-        case 0x8225: // GL_COMPRESSED_RED
-        case 0x8226: // GL_COMPRESSED_RG
-        case 0x84ED: // GL_COMPRESSED_RGB
-        case 0x84EE: // GL_COMPRESSED_RGBA
-        case 0x8C48: // GL_COMPRESSED_SRGB
-        case 0x8C49: // GL_COMPRESSED_SRGB_ALPHA
-            return true;
-        default:
-            break;
-        }
-        return (internalformat >= 0x83F0 && internalformat <= 0x83F3) || // S3TC / DXT
-               (internalformat >= 0x8DBB && internalformat <= 0x8DBE) || // RGTC
-               (internalformat >= 0x8E8C && internalformat <= 0x8E8F) || // BPTC
-               (internalformat >= 0x9270 && internalformat <= 0x9279) || // ETC2 / EAC
-               (internalformat >= 0x93B0 && internalformat <= 0x93BD) || // ASTC LDR
-               (internalformat >= 0x93D0 && internalformat <= 0x93DD);   // ASTC sRGB
-    }
-
     void TextureStorage3D(GLuint texture, GLsizei levels, GLenum internalformat, GLsizei width, GLsizei height,
                           GLsizei depth) {
         auto textureObject = GetTextureObjectByName(texture, __func__);
@@ -4515,6 +4882,10 @@ namespace MobileGL::MG_Impl::GLImpl {
         // Array targets keep their layer count constant across levels; only true 3D
         // textures halve depth per level (GL 3.3 §3.9 glTexStorage3D).
         const Bool depthMips = DepthParticipatesInMipmapping(textureObject->GetTarget());
+        // The same specific-compressed-format tag glTexStorage2D records, for the array targets a
+        // compressed glTexStorage3D is legal on (GL_TEXTURE_3D was refused above). Zero width means
+        // a generic format, which MobileGL answers with uncompressed storage, so it is not tagged.
+        const auto compressedInfo = MG_Util::GetCompressedFormatInfo(internalformat);
         for (GLsizei level = 0; level < levels; ++level) {
             const GLsizei levelWidth = std::max<GLsizei>(1, width >> level);
             const GLsizei levelHeight = std::max<GLsizei>(1, height >> level);
@@ -4524,6 +4895,19 @@ namespace MobileGL::MG_Impl::GLImpl {
             textureMipmapObject->AllocateStorage(textureUploadTarget, level,
                                                  {{levelWidth, levelHeight, levelDepth}, byteSize});
             textureMipmapObject->MarkStorageDirty(textureUploadTarget, level, false);
+            if (compressedInfo.blockWidth != 0) {
+                // After AllocateStorage, which clears the tag.
+                textureMipmapObject->SetMipmapCompressedImage(
+                    textureUploadTarget, static_cast<Uint>(level), internalformat, nullptr,
+                    MG_Util::CalculateCompressedTextureImageSize(compressedInfo,
+                                                                 {levelWidth, levelHeight, levelDepth}));
+            }
+            if (IsCompressedGLInternalFormat(internalformat)) {
+                // Also after AllocateStorage. The generic enums land here and nowhere above,
+                // and glClearTexImage has to refuse them too (GL 4.6 core 8.19).
+                textureMipmapObject->SetMipmapRequestedCompressedFormat(textureUploadTarget,
+                                                                        static_cast<Uint>(level), internalformat);
+            }
         }
         // See TextureStorage1D.
         textureMipmapObject->TruncateMipmapLevels(textureUploadTarget, static_cast<Uint>(levels));
@@ -4684,6 +5068,22 @@ namespace MobileGL::MG_Impl::GLImpl {
         TextureStorage3D(textureObject->GetExternalIndex(), levels, internalformat, width, height, depth);
     }
 
+    // Unlike glTexImage*Multisample, where a zero-sized image is a legal deallocation (see
+    // AllocateMultisampleTextureStorage), the immutable forms take a strictly positive size: GL
+    // 4.6 core 8.19 makes width, height or depth < 1 INVALID_VALUE. Without this the shared
+    // _State helper would deallocate the image and TexStorageMultisample_State would then freeze
+    // the now-imageless texture as immutable.
+    static Bool ValidateTexStorageMultisampleSize(GLsizei width, GLsizei height, GLsizei depth, const char* caller) {
+        if (width >= 1 && height >= 1 && depth >= 1) {
+            return true;
+        }
+        MG_State::pGLContext->RecordError(
+            ErrorCode::InvalidValue,
+            MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", caller,
+                                         "Immutable multisample storage requires width, height and depth >= 1."));
+        return false;
+    }
+
     // The multisample storage forms allocate exactly what the glTexImage*Multisample ones do, and
     // then freeze it: TEXTURE_IMMUTABLE_FORMAT becomes TRUE and a second call is INVALID_OPERATION
     // (GL 4.6 core 8.19). Only the allocation was shared before, so a multisample texture stayed
@@ -4704,6 +5104,7 @@ namespace MobileGL::MG_Impl::GLImpl {
         const TextureTarget textureTarget = MG_Util::ConvertGLEnumToTextureTarget(target);
         auto& activeUnit = MG_State::pGLContext->GetTextureUnitObject(MG_State::pGLContext->GetActiveTextureUnit());
         if (!ValidateTextureMutable(activeUnit.GetBindingSlot(textureTarget).GetBoundObject(), __func__)) return;
+        if (!ValidateTexStorageMultisampleSize(width, height, 1, __func__)) return;
         TexStorageMultisample_State(
             target, TexImage2DMultisample_State(target, samples, internalformat, width, height, fixedsamplelocations),
             __func__);
@@ -4714,6 +5115,7 @@ namespace MobileGL::MG_Impl::GLImpl {
         const TextureTarget textureTarget = MG_Util::ConvertGLEnumToTextureTarget(target);
         auto& activeUnit = MG_State::pGLContext->GetTextureUnitObject(MG_State::pGLContext->GetActiveTextureUnit());
         if (!ValidateTextureMutable(activeUnit.GetBindingSlot(textureTarget).GetBoundObject(), __func__)) return;
+        if (!ValidateTexStorageMultisampleSize(width, height, depth, __func__)) return;
         TexStorageMultisample_State(target,
                                     TexImage3DMultisample_State(target, samples, internalformat, width, height, depth,
                                                                 fixedsamplelocations),
@@ -5715,17 +6117,29 @@ namespace MobileGL::MG_Impl::GLImpl {
                           GLuint dstName, GLenum dstTarget, GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ,
                           GLsizei srcWidth, GLsizei srcHeight, GLsizei srcDepth) {
         // A missing name is INVALID_VALUE here, where GetTextureObjectByName's own diagnostic is
-        // INVALID_OPERATION - so resolve through the plain lookup, which answers a null
+        // INVALID_OPERATION - so resolve through the plain lookups, which answer a null
         // SharedPtr, and let the validator record the error this entry point owes.
-        const SharedPtr<MG_State::GLState::ITextureObject> srcTexture =
-            MG_State::pGLContext->GetTextureObject(srcName);
-        const SharedPtr<MG_State::GLState::ITextureObject> dstTexture =
-            MG_State::pGLContext->GetTextureObject(dstName);
-        if (!ValidateCopyImageSubData_State(srcTexture, srcTarget, srcLevel, srcX, srcY, dstTexture, dstTarget,
-                                            dstLevel, dstX, dstY, srcWidth, srcHeight, srcDepth)) {
+        //
+        // The TARGET picks the namespace: GL 4.6 core 18.3.2 accepts GL_RENDERBUFFER, and a
+        // renderbuffer name has nothing to do with a texture name. Resolving both through
+        // GetTextureObject made every renderbuffer endpoint INVALID_VALUE - or, when the number
+        // happened to collide with a live texture, INVALID_ENUM from the target check.
+        const auto resolveEndpoint = [](GLuint name, GLenum target) {
+            MG_Backend::CopyImageEndpoint endpoint{};
+            if (target == GL_RENDERBUFFER) {
+                endpoint.Renderbuffer = MG_State::pGLContext->GetRenderbufferObject(name);
+            } else {
+                endpoint.Texture = MG_State::pGLContext->GetTextureObject(name);
+            }
+            return endpoint;
+        };
+        const MG_Backend::CopyImageEndpoint src = resolveEndpoint(srcName, srcTarget);
+        const MG_Backend::CopyImageEndpoint dst = resolveEndpoint(dstName, dstTarget);
+        if (!ValidateCopyImageSubData_State(src, srcTarget, srcLevel, srcX, srcY, srcZ, dst, dstTarget,
+                                            dstLevel, dstX, dstY, dstZ, srcWidth, srcHeight, srcDepth)) {
             return;
         }
-        CopyImageSubData_Backend(srcTexture, srcTarget, srcLevel, srcX, srcY, srcZ, dstTexture, dstTarget, dstLevel,
+        CopyImageSubData_Backend(src, srcTarget, srcLevel, srcX, srcY, srcZ, dst, dstTarget, dstLevel,
                                  dstX, dstY, dstZ, srcWidth, srcHeight, srcDepth);
     }
 

MobileGL/MG_Impl/GLImpl/Texture/Validators.cpp

@@ -313,9 +313,13 @@ namespace MobileGL::MG_Impl::GLImpl::TextureImpl {
             return false;
         }
 
-        // TexImage in core 3.3 has no stencil-only upload path (that arrived with GL 4.4).
-        if (format == TextureInputFormat::StencilIndex) {
-            return recordInvalidOperation("STENCIL_INDEX is not a valid texture upload format");
+        // The stencil-only transfer path arrived with GL 4.4 / ARB_texture_stencil8, and only ever
+        // pairs with stencil-only storage: against a depth, depth-stencil or colour internal format
+        // STENCIL_INDEX keeps the pre-4.4 answer (GL CTS packed_pixels feeds exactly that pairing
+        // and expects INVALID_OPERATION).
+        if (format == TextureInputFormat::StencilIndex &&
+            internalFormat != TextureInternalFormat::StencilIndex8) {
+            return recordInvalidOperation("STENCIL_INDEX requires a stencil-only internal format");
         }
 
         if (IsDepthLikeInputFormat(format) != IsDepthLikeInternalFormat(internalFormat)) {

MobileGL/MG_Impl/GLImpl/VertexArray/GL_VertexArray.cpp

@@ -514,10 +514,15 @@ namespace MobileGL::MG_Impl::GLImpl {
     // recorded DataType is always Float64 - what IsLong adds is that this is the *unconverted* form,
     // as opposed to VertexAttribFormat(GL_DOUBLE), which asks for a float conversion.
     //
-    // Whether the backend can feed it is detected, not assumed: DirectVulkan needs shaderFloat64,
-    // and DirectGLES can never have it at all. A backend without it declines here, loudly - GL error
-    // plus a log line naming the reason - rather than accepting state no draw could honour and
-    // rendering garbage. The matching startup POST row is in MG_Util/SelfTest/DriverPost.cpp.
+    // Whether the backend can FEED it is detected, not assumed: DirectVulkan needs shaderFloat64,
+    // and DirectGLES can never have it at all. What that costs is the ARRAY, not the call: GL 4.6
+    // core 10.3.2 defines no error for a well-formed glVertexAttribLFormat, and a GL 4.3 context
+    // has 64-bit attributes in core, so declining the call would be non-conformant and would make
+    // the four pure state queries (VERTEX_ATTRIB_ARRAY_SIZE / _TYPE / _LONG / _RELATIVE_OFFSET)
+    // unanswerable (KHR-GL43.vertex_attrib_binding.basic-state1/3). The format is therefore
+    // RECORDED here and the enabled array is dropped at draw instead - loudly, once, naming the
+    // reason. The matching startup POST row is in MG_Util/SelfTest/DriverPost.cpp; the draw-side
+    // drop is DirectGLES/Managers.cpp and, on DirectVulkan, VertexInputStateFactory's Float64 case.
     static void VertexAttribLFormatSeparate_State(const SharedPtr<MG_State::GLState::VertexArrayObject>& vao,
                                                   GLuint attribindex, GLint size, GLenum type,
                                                   GLuint relativeoffset) {
@@ -528,14 +533,11 @@ namespace MobileGL::MG_Impl::GLImpl {
         if (!MG_Backend::pActiveBackendObject ||
             !MG_Backend::pActiveBackendObject->GetDynamicParameters().SupportsFloat64VertexAttributes) {
             MGLOG_W_ONCE("VertexAttribLFormat: attribute %u asked for a 64-bit (GL_DOUBLE) format, but this "
-                    "backend has no double-precision vertex attribute support - see the "
-                    "\"64-bit vertex attributes\" / \"shaderFloat64\" POST row for what that costs",
+                    "backend has no double-precision vertex attribute support - the format is recorded "
+                    "and queryable, but the array will be DROPPED at draw and the attribute will read "
+                    "its generic current value; see the \"64-bit vertex attributes\" / \"shaderFloat64\" "
+                    "POST row for what that costs",
                     attribindex);
-            MG_State::pGLContext->RecordError(
-                ErrorCode::InvalidOperation,
-                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", "VertexAttribLFormat",
-                                             "64-bit vertex attributes are not supported by this backend."));
-            return;
         }
 
         vao->SetAttributeFormatSeparate(attribindex, size, MG_Util::ConvertGLEnumToDataType(type),

MobileGL/MG_IntegrationTest/CMakeLists.txt

@@ -59,6 +59,7 @@ add_executable(MobileGLIntegrationTest
     Scenarios/AsyncCompileScenario.cpp
     Scenarios/XfbAfterClipDistanceScenario.cpp
     Scenarios/ThreeChannelAttachmentScenario.cpp
+    Scenarios/SnormAttachmentScenario.cpp
     Scenarios/PipelineFailureScenario.cpp
     Scenarios/AdvertisedLimitsScenario.cpp
     Scenarios/PixelStoreSweepScenario.cpp
@@ -80,16 +81,22 @@ add_executable(MobileGLIntegrationTest
     Scenarios/ImageLoadStoreSsoScenario.cpp
     Scenarios/ImageTargetKindScenario.cpp
     Scenarios/ImageFormatQualifierScenario.cpp
+    Scenarios/ImageSizeAfterRespecScenario.cpp
     Scenarios/SsboDeclarationFormScenario.cpp
     Scenarios/Glsl420DeclarationScenario.cpp
+    Scenarios/IoBlockNameCollisionScenario.cpp
     Scenarios/FragmentOutputArrayIndexScenario.cpp
     Scenarios/BufferTextureScenario.cpp
     Scenarios/VertexAttribBindingScenario.cpp
     Scenarios/XfbCaptureBufferReuseScenario.cpp
+    Scenarios/XfbPrimitiveQueryScenario.cpp
     Scenarios/VertexArrayEnableDisableScenario.cpp
     Scenarios/CopyImageLevelRangeScenario.cpp
     Scenarios/CopyImageLayeredScenario.cpp
+    Scenarios/PackedWordReadbackScenario.cpp
     Scenarios/LayeredAttachmentBarrierScenario.cpp
+    Scenarios/LayeredTextureReadbackScenario.cpp
+    Scenarios/AtomicCounterScenario.cpp
 )
 
 target_include_directories(MobileGLIntegrationTest PRIVATE
@@ -246,6 +253,19 @@ endif()
 set(MGL_ITEST_VULKAN_ENV ${MGL_ITEST_COMMON_ENV})
 if (MOBILEGL_ITEST_VK_ICD)
     list(APPEND MGL_ITEST_VULKAN_ENV "VK_ICD_FILENAMES=${MOBILEGL_ITEST_VK_ICD}")
+    # The three iterationRP repairs are tri-state quirks that default to device
+    # auto-detection, and lavapipe is not on any auto list - so on lavapipe the
+    # iterationRP scenarios run unrepaired and Program 203 misses its golden
+    # output. CI's integration-gpu job exports these three by hand; pinning them
+    # to the ICD instead means a local `ctest -L integration-gpu` measures the
+    # same thing the gate does, with no environment to remember.
+    if (MOBILEGL_ITEST_VK_ICD MATCHES "lvp_icd|lavapipe")
+        message(STATUS "Integration tests: lavapipe ICD - forcing the iterationRP repairs on")
+        list(APPEND MGL_ITEST_VULKAN_ENV
+            "MOBILEGL_FIX_ITERATIONRP_SUBGROUP_SCRATCH=1"
+            "MOBILEGL_DERIVE_NUM_SUBGROUPS=1"
+            "MOBILEGL_ITERATIONRP_FIX_BARRIER=1")
+    endif()
 endif()
 
 # The ENVIRONMENT test property is itself a `;`-list, and gtest_discover_tests

MobileGL/MG_IntegrationTest/Scenarios/AtomicCounterScenario.cpp

@@ -0,0 +1,239 @@
+// MobileGL - MobileGL/MG_IntegrationTest/Scenarios/AtomicCounterScenario.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// Scenario - ATOMIC COUNTERS, END TO END.
+//
+// GL_ATOMIC_COUNTER_BUFFER does not exist in ES, and glslang does not hand one to a backend
+// either: its Vulkan-relaxed parse rewrites every atomic_uint into a uint member of a
+// synthesized gl_AtomicCounterBlock_<N> STORAGE block. Making counters work therefore means
+// closing two open ends that used to be missing entirely -
+//
+//   * the block's shader-storage binding, which the IO mapper picked at random and which had no
+//     relation to the GL binding point N the application bound its buffer to (and could alias an
+//     SSBO the application binds itself), is moved to a slot reserved at the top of the driver's
+//     range; and
+//   * the buffer bound at GL_ATOMIC_COUNTER_BUFFER point N, which nothing in the ES backend ever
+//     read, is re-issued as a shader-storage binding at that reserved slot.
+//
+// Neither end alone is observable: with only the first the shader increments a block nobody
+// bound a buffer to, with only the second the buffer lands where the shader does not look. The
+// only thing that proves both is the VALUE, so every assertion here reads the counter back.
+//
+// Compute rather than a draw on purpose: the invocation count is exactly what was dispatched,
+// while a fragment stage's is a property of the rasterizer (helper invocations, early depth).
+// Conformance cases behind this: KHR-GL42/GL43.shader_atomic_counters.basic-usage-cs,
+// .advanced-usage-multi-stage and .advanced-usage-draw-update-draw.
+
+#include <string>
+#include <vector>
+
+#include "../Harness/HeadlessGL.h"
+#include "../Harness/ScenarioFixture.h"
+
+#ifdef GLAPI
+#undef GLAPI
+#endif
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glcorearb.h>
+#undef GL_GLEXT_PROTOTYPES
+
+namespace MGITest {
+    namespace {
+
+        // Two counters share binding 0 at DIFFERENT offsets and a third sits alone on binding 1.
+        // The offsets are what separates "the buffer arrived" from "the buffer arrived and the
+        // block is laid out the way GL says": a lowering that packed the members in declaration
+        // order without honouring `offset` would still pass a single-counter check.
+        constexpr const char* kCounterComputeSource = R"(#version 430 core
+layout(local_size_x = 4) in;
+layout(binding = 0, offset = 0) uniform atomic_uint g_first;
+layout(binding = 0, offset = 4) uniform atomic_uint g_second;
+layout(binding = 1, offset = 0) uniform atomic_uint g_other;
+void main() {
+    atomicCounterIncrement(g_first);
+    atomicCounterIncrement(g_second);
+    atomicCounterIncrement(g_second);
+    atomicCounterIncrement(g_other);
+}
+)";
+
+        constexpr int kLocalSizeX = 4;
+        constexpr int kWorkGroups = 2;
+        constexpr unsigned int kInvocations = kLocalSizeX * kWorkGroups;
+
+        // Deliberately non-zero: the shader adds to whatever the application uploaded, so a seed
+        // that survives is also proof that the buffer's CPU-side contents reached the driver.
+        constexpr unsigned int kSeedFirst = 5;
+        constexpr unsigned int kSeedSecond = 100;
+        constexpr unsigned int kSeedOther = 7;
+
+        class AtomicCounterScenario : public ScenarioTest {
+        protected:
+            void SetUp() override {
+                ScenarioTest::SetUp();
+                if (!Ready()) return;
+                GLint counters = 0;
+                glGetIntegerv(GL_MAX_COMPUTE_ATOMIC_COUNTERS, &counters);
+                GLint buffers = 0;
+                glGetIntegerv(GL_MAX_COMPUTE_ATOMIC_COUNTER_BUFFERS, &buffers);
+                if (counters < 3 || buffers < 2) {
+                    GTEST_SKIP() << "GL_MAX_COMPUTE_ATOMIC_COUNTERS is " << counters
+                                 << " and GL_MAX_COMPUTE_ATOMIC_COUNTER_BUFFERS is " << buffers
+                                 << "; this needs 3 and 2";
+                }
+                if (!AtomicCountersAreWired()) {
+                    GTEST_SKIP() << "atomic counter buffers are not wired up on " << Gl().BackendName()
+                                 << " yet: glslang lowers them onto a storage block and that block's descriptor "
+                                 << "is still resolved from the shader-storage binding points";
+                }
+                m_program = CompileComputeProgram(kCounterComputeSource);
+                ASSERT_NE(m_program, 0u) << m_buildLog;
+            }
+
+            void TearDown() override {
+                if (!Ready()) return;
+                glUseProgram(0);
+                if (!m_buffers.empty()) glDeleteBuffers(static_cast<GLsizei>(m_buffers.size()), m_buffers.data());
+                if (m_program != 0) glDeleteProgram(m_program);
+                m_buffers.clear();
+                m_program = 0;
+            }
+
+            // Magma binds the lowered block as an ordinary storage-buffer descriptor resolved
+            // from GL_SHADER_STORAGE_BUFFER point N, so the counter buffer never reaches it. The
+            // frontend half (limits, reflection queries, the link-time offset rules) is
+            // backend-agnostic and is covered by the unit suites; only the VALUE is scoped here.
+            bool AtomicCountersAreWired() const { return Gl().BackendName() != "DirectVulkan"; }
+
+            unsigned int CompileComputeProgram(const char* source) {
+                const GLuint shader = glCreateShader(GL_COMPUTE_SHADER);
+                glShaderSource(shader, 1, &source, nullptr);
+                glCompileShader(shader);
+                GLint compiled = 0;
+                glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+                if (compiled == GL_FALSE) {
+                    char log[2048] = {};
+                    glGetShaderInfoLog(shader, sizeof(log) - 1, nullptr, log);
+                    m_buildLog = std::string("compute shader did not compile: ") + log;
+                    glDeleteShader(shader);
+                    return 0;
+                }
+                const GLuint program = glCreateProgram();
+                glAttachShader(program, shader);
+                glLinkProgram(program);
+                glDeleteShader(shader);
+                GLint linked = 0;
+                glGetProgramiv(program, GL_LINK_STATUS, &linked);
+                if (linked == GL_FALSE) {
+                    char log[2048] = {};
+                    glGetProgramInfoLog(program, sizeof(log) - 1, nullptr, log);
+                    m_buildLog = std::string("compute program did not link: ") + log;
+                    glDeleteProgram(program);
+                    return 0;
+                }
+                return program;
+            }
+
+            // A counter buffer of `count` uints, seeded and bound to atomic-counter point
+            // `binding`.
+            GLuint MakeCounterBuffer(GLuint binding, const std::vector<unsigned int>& seed) {
+                GLuint buffer = 0;
+                glGenBuffers(1, &buffer);
+                glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, buffer);
+                glBufferData(GL_ATOMIC_COUNTER_BUFFER,
+                             static_cast<GLsizeiptr>(seed.size() * sizeof(unsigned int)), seed.data(),
+                             GL_DYNAMIC_DRAW);
+                glBindBufferBase(GL_ATOMIC_COUNTER_BUFFER, binding, buffer);
+                glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, 0);
+                m_buffers.push_back(buffer);
+                return buffer;
+            }
+
+            std::vector<unsigned int> ReadCounters(GLuint buffer, int count) {
+                std::vector<unsigned int> values(static_cast<std::size_t>(count), 0xDEADBEEFu);
+                glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, buffer);
+                glGetBufferSubData(GL_ATOMIC_COUNTER_BUFFER, 0,
+                                   static_cast<GLsizeiptr>(values.size() * sizeof(unsigned int)), values.data());
+                glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, 0);
+                return values;
+            }
+
+            void Dispatch() {
+                glUseProgram(m_program);
+                glDispatchCompute(kWorkGroups, 1, 1);
+                glMemoryBarrier(GL_ATOMIC_COUNTER_BARRIER_BIT | GL_BUFFER_UPDATE_BARRIER_BIT);
+            }
+
+            unsigned int m_program = 0;
+            std::string m_buildLog;
+            std::vector<GLuint> m_buffers;
+        };
+
+    } // namespace
+
+    // The counter values a dispatch leaves behind, per binding point and per offset within one
+    // binding. Nothing in the ES backend used to touch BufferTarget::AtomicCounter at all, so
+    // before the wiring landed every one of these read back its seed unchanged.
+    TEST_F(AtomicCounterScenario, DispatchIncrementsTheBoundCounterBuffers) {
+        if (!Ready() || IsSkipped()) return;
+
+        const GLuint zero = MakeCounterBuffer(0, {kSeedFirst, kSeedSecond});
+        const GLuint one = MakeCounterBuffer(1, {kSeedOther});
+        ASSERT_EQ(FirstGLError(), 0u) << "binding the counter buffers raised a GL error";
+
+        Dispatch();
+        EXPECT_EQ(FirstGLError(), 0u) << "the dispatch raised a GL error";
+
+        const std::vector<unsigned int> zeroValues = ReadCounters(zero, 2);
+        const std::vector<unsigned int> oneValues = ReadCounters(one, 1);
+        EXPECT_EQ(FirstGLError(), 0u) << "reading the counters back raised a GL error";
+
+        EXPECT_EQ(zeroValues[0], kSeedFirst + kInvocations)
+            << "binding 0 offset 0 read back " << zeroValues[0] << "; " << kSeedFirst
+            << " means the shader's increments never reached the buffer the application bound";
+        EXPECT_EQ(zeroValues[1], kSeedSecond + 2 * kInvocations)
+            << "binding 0 offset 4 read back " << zeroValues[1] << "; the seed means the counter at a NON-ZERO "
+            << "offset was not carried through the lowering, even though offset 0 was";
+        EXPECT_EQ(oneValues[0], kSeedOther + kInvocations)
+            << "binding 1 read back " << oneValues[0] << "; a counter buffer past the first binding point "
+            << "resolves to a different reserved slot and is where an off-by-one shows up";
+    }
+
+    // A second dispatch continues from where the first left off, and a re-seed between them is
+    // visible to the shader. Both halves of the buffer's traffic have to work, in both
+    // directions: the increments are only observable through the readback path, and the re-seed
+    // is only observable if the upload reaches the driver AFTER the buffer has been GPU-written.
+    TEST_F(AtomicCounterScenario, CountersAccumulateAcrossDispatchesAndFollowAReseed) {
+        if (!Ready() || IsSkipped()) return;
+
+        const GLuint zero = MakeCounterBuffer(0, {0u, 0u});
+        MakeCounterBuffer(1, {0u});
+        ASSERT_EQ(FirstGLError(), 0u);
+
+        Dispatch();
+        Dispatch();
+        std::vector<unsigned int> values = ReadCounters(zero, 2);
+        EXPECT_EQ(FirstGLError(), 0u);
+        EXPECT_EQ(values[0], 2 * kInvocations) << "two dispatches did not accumulate";
+        EXPECT_EQ(values[1], 4 * kInvocations) << "two dispatches did not accumulate at offset 4";
+
+        const unsigned int reseed[2] = {1000u, 2000u};
+        glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, zero);
+        glBufferSubData(GL_ATOMIC_COUNTER_BUFFER, 0, sizeof(reseed), reseed);
+        glBindBuffer(GL_ATOMIC_COUNTER_BUFFER, 0);
+        ASSERT_EQ(FirstGLError(), 0u) << "re-seeding the counter buffer raised a GL error";
+
+        Dispatch();
+        values = ReadCounters(zero, 2);
+        EXPECT_EQ(FirstGLError(), 0u);
+        EXPECT_EQ(values[0], reseed[0] + kInvocations) << "the re-seeded value did not reach the shader";
+        EXPECT_EQ(values[1], reseed[1] + 2 * kInvocations) << "the re-seeded value at offset 4 did not reach the shader";
+    }
+
+} // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/BufferTextureScenario.cpp

@@ -299,4 +299,99 @@ void main() {
         EXPECT_EQ(FirstGLError(), 0u);
     }
 
+    // glGetTexLevelParameter used to refuse EVERY pname on a buffer texture: WIDTH/HEIGHT/DEPTH
+    // fell out of a mipmap-only switch as GL_INVALID_OPERATION, and GL_TEXTURE_BUFFER_SIZE /
+    // GL_TEXTURE_BUFFER_OFFSET were not in the switch at all, so they came back GL_INVALID_ENUM.
+    // KHR-GL43.texture_buffer wraps both queries in GLU_EXPECT_NO_ERROR, so the error alone fails
+    // the case before any value is compared.
+    //
+    // The two halves report DIFFERENT units and only one of them is clamped, which is the thing
+    // easiest to get backwards: WIDTH is a TEXEL count clamped to GL_MAX_TEXTURE_BUFFER_SIZE,
+    // BUFFER_SIZE is the range in basic machine units exactly as it was given.
+    TEST_F(BufferTextureScenario, LevelQueriesDescribeTheAttachedBufferRange) {
+        if (!Ready()) return;
+        FirstGLError();
+
+        GLint offsetAlignment = 1;
+        glGetIntegerv(GL_TEXTURE_BUFFER_OFFSET_ALIGNMENT, &offsetAlignment);
+        if (offsetAlignment < 1) offsetAlignment = 1;
+        GLint maxTexels = 0;
+        glGetIntegerv(GL_MAX_TEXTURE_BUFFER_SIZE, &maxTexels);
+        ASSERT_EQ(FirstGLError(), 0u);
+        ASSERT_GT(maxTexels, 0) << "an OpenGL 4.x context may not advertise a zero buffer-texture limit";
+
+        constexpr GLint kTexelBytes = 4; // GL_RGBA8
+        const GLsizeiptr rangeOffset = static_cast<GLsizeiptr>(offsetAlignment);
+        const GLsizeiptr rangeBytes = 32 * kTexelBytes;
+        // Deliberately bigger than the range, so a getter that answered out of the BUFFER rather
+        // than out of the texture's window would be caught.
+        const GLsizeiptr bufferBytes = rangeOffset + rangeBytes + 16 * kTexelBytes;
+
+        const std::vector<GLubyte> zeros(static_cast<size_t>(bufferBytes), 0);
+        GLuint buffer = 0;
+        glGenBuffers(1, &buffer);
+        glBindBuffer(GL_TEXTURE_BUFFER, buffer);
+        glBufferData(GL_TEXTURE_BUFFER, bufferBytes, zeros.data(), GL_STATIC_DRAW);
+
+        GLuint texture = 0;
+        glGenTextures(1, &texture);
+        glBindTexture(GL_TEXTURE_BUFFER, texture);
+        glTexBufferRange(GL_TEXTURE_BUFFER, GL_RGBA8, buffer, rangeOffset, rangeBytes);
+        ASSERT_EQ(FirstGLError(), 0u) << "glTexBufferRange(GL_RGBA8) was refused";
+
+        const auto levelQuery = [](GLenum pname) {
+            GLint value = -1;
+            glGetTexLevelParameteriv(GL_TEXTURE_BUFFER, 0, pname, &value);
+            return value;
+        };
+        const auto levelQueryF = [](GLenum pname) {
+            GLfloat value = -1.0f;
+            glGetTexLevelParameterfv(GL_TEXTURE_BUFFER, 0, pname, &value);
+            return value;
+        };
+
+        EXPECT_EQ(levelQuery(GL_TEXTURE_WIDTH), static_cast<GLint>(rangeBytes / kTexelBytes))
+            << "GL_TEXTURE_WIDTH is a texel count over the attached RANGE";
+        EXPECT_EQ(levelQuery(GL_TEXTURE_HEIGHT), 1);
+        EXPECT_EQ(levelQuery(GL_TEXTURE_DEPTH), 1);
+        EXPECT_EQ(levelQuery(GL_TEXTURE_BUFFER_SIZE), static_cast<GLint>(rangeBytes))
+            << "GL_TEXTURE_BUFFER_SIZE reports basic machine units, not texels";
+        EXPECT_EQ(levelQuery(GL_TEXTURE_BUFFER_OFFSET), static_cast<GLint>(rangeOffset));
+        EXPECT_EQ(FirstGLError(), 0u) << "a buffer-texture level query raised an error";
+        EXPECT_LE(levelQuery(GL_TEXTURE_WIDTH), maxTexels)
+            << "GL_TEXTURE_WIDTH must stay clamped to GL_MAX_TEXTURE_BUFFER_SIZE";
+
+        // The float getter is a separate switch and has drifted from the integer one before.
+        EXPECT_FLOAT_EQ(levelQueryF(GL_TEXTURE_WIDTH), static_cast<GLfloat>(rangeBytes / kTexelBytes));
+        EXPECT_FLOAT_EQ(levelQueryF(GL_TEXTURE_HEIGHT), 1.0f);
+        EXPECT_FLOAT_EQ(levelQueryF(GL_TEXTURE_BUFFER_SIZE), static_cast<GLfloat>(rangeBytes));
+        EXPECT_EQ(FirstGLError(), 0u) << "the float form of a buffer-texture level query raised an error";
+
+        // The whole-buffer form follows the buffer's current size instead of freezing a window.
+        glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA8, buffer);
+        EXPECT_EQ(levelQuery(GL_TEXTURE_BUFFER_OFFSET), 0);
+        EXPECT_EQ(levelQuery(GL_TEXTURE_BUFFER_SIZE), static_cast<GLint>(bufferBytes));
+        EXPECT_EQ(levelQuery(GL_TEXTURE_WIDTH), static_cast<GLint>(bufferBytes / kTexelBytes));
+        EXPECT_EQ(FirstGLError(), 0u);
+
+        // Both buffer pnames belong to buffer textures alone; anything else is INVALID_OPERATION,
+        // the same shape GL_TEXTURE_COMPRESSED_IMAGE_SIZE uses for an uncompressed image.
+        GLuint plainTexture = 0;
+        glGenTextures(1, &plainTexture);
+        glBindTexture(GL_TEXTURE_2D, plainTexture);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 4, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+        EXPECT_EQ(FirstGLError(), 0u);
+        GLint unused = -1;
+        glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_BUFFER_SIZE, &unused);
+        EXPECT_EQ(FirstGLError(), static_cast<unsigned int>(GL_INVALID_OPERATION));
+
+        glBindTexture(GL_TEXTURE_2D, 0);
+        glBindTexture(GL_TEXTURE_BUFFER, 0);
+        glBindBuffer(GL_TEXTURE_BUFFER, 0);
+        glDeleteTextures(1, &plainTexture);
+        glDeleteTextures(1, &texture);
+        glDeleteBuffers(1, &buffer);
+        EXPECT_EQ(FirstGLError(), 0u);
+    }
+
 } // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/ClipDistanceScenario.cpp

@@ -151,6 +151,18 @@ void main() { fragColor = vec4(0.0, 1.0, 0.0, 1.0); }
                 glReadPixels(x, y, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, out);
             }
 
+            // GL_MAX_CLIP_DISTANCES is a real backend answer, not a constant: DirectGLES reports
+            // 0 on a driver without GL_EXT_clip_cull_distance, and DirectVulkan reports 0 without
+            // the shaderClipDistance device feature. On such a stack the shader above cannot
+            // compile - and MUST not, because declaring a clip distance the backend cannot host
+            // is exactly what used to link cleanly and then render nothing. Skip rather than
+            // fail: there is no clipping to assert about.
+            static bool BackendHostsTwoClipDistances() {
+                GLint maxClipDistances = 0;
+                glGetIntegerv(GL_MAX_CLIP_DISTANCES, &maxClipDistances);
+                return maxClipDistances >= 2;
+            }
+
             // Never assume the eight start disabled - see the header note about
             // XfbAfterClipDistanceScenario leaving one on for the rest of the process.
             static void DisableEveryClipDistance() {
@@ -229,6 +241,9 @@ void main() { fragColor = vec4(0.0, 1.0, 0.0, 1.0); }
     // The claim: an enabled clip distance removes the fragments where it is negative.
     TEST_F(ClipDistanceScenario, AnEnabledClipDistanceRemovesTheNegativeHalf) {
         if (!Ready()) return;
+        if (!BackendHostsTwoClipDistances()) {
+            GTEST_SKIP() << "this backend advertises no clip distances, so there is nothing to clip with";
+        }
         HeadlessGL& gl = Gl();
         const int width = gl.Width();
         const int height = gl.Height();
@@ -280,6 +295,9 @@ void main() { fragColor = vec4(0.0, 1.0, 0.0, 1.0); }
     // draw simply failed - would pass the case above.
     TEST_F(ClipDistanceScenario, ADisabledClipDistanceRemovesNothing) {
         if (!Ready()) return;
+        if (!BackendHostsTwoClipDistances()) {
+            GTEST_SKIP() << "this backend advertises no clip distances, so there is nothing to clip with";
+        }
         HeadlessGL& gl = Gl();
         const int width = gl.Width();
         const int height = gl.Height();
@@ -329,6 +347,9 @@ void main() { fragColor = vec4(0.0, 1.0, 0.0, 1.0); }
     // passes both cases above and fails this one.
     TEST_F(ClipDistanceScenario, TheEnablesAreIndependentPerDistance) {
         if (!Ready()) return;
+        if (!BackendHostsTwoClipDistances()) {
+            GTEST_SKIP() << "this backend advertises no clip distances, so there is nothing to clip with";
+        }
         HeadlessGL& gl = Gl();
         const int width = gl.Width();
         const int height = gl.Height();

MobileGL/MG_IntegrationTest/Scenarios/DoublePrecisionScenario.cpp

@@ -697,24 +697,127 @@ void main() {
             EXPECT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR));
         }
 
-        TEST_F(DoublePrecisionScenario, A64BitVertexFormatIsDeclinedOnEveryBackend) {
+        TEST_F(DoublePrecisionScenario, A64BitVertexFormatIsRecordedAndItsArrayIsDroppedAtDraw) {
             if (!Ready()) return;
             // The demotion leaves no 64-bit shader input to feed, so there is nothing a 64-bit
             // vertex FETCH could be fetched into - on either backend, and no longer only on the
-            // ones whose device lacks shaderFloat64. Declined loudly rather than accepted and
-            // drawn as garbage; the matching POST row says the same thing at startup.
+            // ones whose device lacks shaderFloat64.
+            //
+            // What that costs is the ARRAY, not the CALL. GL 4.6 core 10.3.2 defines no error for
+            // a well-formed glVertexAttribLFormat and 64-bit attributes are core in the GL 4.3
+            // context MobileGL advertises, so refusing the call would be non-conformant and would
+            // leave four pure state queries unanswerable
+            // (KHR-GL43.vertex_attrib_binding.basic-state1/3). The format is therefore recorded and
+            // queryable; the enabled array is what gets dropped, and the attribute then reads its
+            // generic current value. The matching POST row says exactly that at startup.
             GLuint vao = 0;
             glGenVertexArrays(1, &vao);
             glBindVertexArray(vao);
             while (glGetError() != GL_NO_ERROR) {}
 
-            glVertexAttribLFormat(0, 3, GL_DOUBLE, 0);
-            EXPECT_EQ(glGetError(), static_cast<GLenum>(GL_INVALID_OPERATION));
+            glVertexAttribLFormat(1, 3, GL_DOUBLE, 8);
+            EXPECT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR))
+                << "glVertexAttribLFormat is a legal call in a GL 4.3 context";
+
+            GLint attribSize = 0;
+            GLint attribType = 0;
+            GLint attribIsLong = 0;
+            GLint attribRelativeOffset = 0;
+            glGetVertexAttribiv(1, GL_VERTEX_ATTRIB_ARRAY_SIZE, &attribSize);
+            glGetVertexAttribiv(1, GL_VERTEX_ATTRIB_ARRAY_TYPE, &attribType);
+            glGetVertexAttribiv(1, GL_VERTEX_ATTRIB_ARRAY_LONG, &attribIsLong);
+            glGetVertexAttribiv(1, GL_VERTEX_ATTRIB_RELATIVE_OFFSET, &attribRelativeOffset);
+            EXPECT_EQ(attribSize, 3);
+            EXPECT_EQ(attribType, static_cast<GLint>(GL_DOUBLE));
+            EXPECT_EQ(attribIsLong, GL_TRUE) << "GL_VERTEX_ATTRIB_ARRAY_LONG is what makes this the "
+                                                "unconverted form; without it the state is a lie";
+            EXPECT_EQ(attribRelativeOffset, 8);
+            EXPECT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR));
 
             glBindVertexArray(0);
             glDeleteVertexArrays(1, &vao);
             while (glGetError() != GL_NO_ERROR) {}
         }
 
+        // The consequence of recording the state rather than refusing the call: a 64-bit array can
+        // now be ENABLED in a VAO that a draw uses, which it never could before. That must not
+        // take the draw down. Leaving such an array enabled with no pointer behind it is exactly
+        // the documented Adreno null-deref (SIGSEGV inside the next glDraw*), so DirectGLES
+        // disables it before glVertexAttribPointer can ever see GL_DOUBLE, and DirectVulkan maps
+        // the format to VK_FORMAT_UNDEFINED so it never enters the pipeline's vertex input state.
+        //
+        // The shader deliberately does NOT read location 1: that keeps the two backends on the
+        // same path (DirectVulkan declines a draw whose SHADER reads an unsupported enabled array,
+        // by design and loudly, which is a different assertion from this one) and it is the shape
+        // the crash needed - an enabled array nothing set a pointer for.
+        TEST_F(DoublePrecisionScenario, AnEnabledLongArrayDoesNotBreakADrawThatIgnoresIt) {
+            if (!Ready()) return;
+
+            constexpr const char* kVs = R"(#version 430 core
+layout(location = 0) in vec2 aPos;
+void main() { gl_Position = vec4(aPos, 0.0, 1.0); }
+)";
+            constexpr const char* kFs = R"(#version 430 core
+out vec4 o_color;
+void main() { o_color = vec4(0.0, 1.0, 0.0, 1.0); }
+)";
+            std::string error;
+            const unsigned int program = CompileProgram(kVs, kFs, &error);
+            ASSERT_NE(program, 0u) << error;
+
+            ColorFbo target = MakeColorFbo(32, 32);
+            ASSERT_NE(target.fbo, 0u) << "could not create the render target";
+            BindFbo(target);
+
+            const float positions[8] = {-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f};
+            const double doubles[4] = {1.0, 2.0, 3.0, 4.0};
+
+            GLuint vao = 0;
+            GLuint positionBuffer = 0;
+            GLuint doubleBuffer = 0;
+            glGenVertexArrays(1, &vao);
+            glBindVertexArray(vao);
+            glGenBuffers(1, &positionBuffer);
+            glBindBuffer(GL_ARRAY_BUFFER, positionBuffer);
+            glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STATIC_DRAW);
+            glGenBuffers(1, &doubleBuffer);
+            glBindBuffer(GL_ARRAY_BUFFER, doubleBuffer);
+            glBufferData(GL_ARRAY_BUFFER, sizeof(doubles), doubles, GL_STATIC_DRAW);
+            glBindBuffer(GL_ARRAY_BUFFER, 0);
+
+            glVertexAttribFormat(0, 2, GL_FLOAT, GL_FALSE, 0);
+            glVertexAttribBinding(0, 0);
+            glBindVertexBuffer(0, positionBuffer, 0, static_cast<GLsizei>(2 * sizeof(float)));
+            glEnableVertexAttribArray(0);
+
+            glVertexAttribLFormat(1, 1, GL_DOUBLE, 0);
+            glVertexAttribBinding(1, 1);
+            glBindVertexBuffer(1, doubleBuffer, 0, static_cast<GLsizei>(sizeof(double)));
+            glEnableVertexAttribArray(1);
+            EXPECT_EQ(FirstGLError(), 0u) << "setting up the 64-bit array was refused";
+
+            ClearTo(0.0f, 0.0f, 0.0f, 1.0f);
+            glUseProgram(program);
+            glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+            EXPECT_EQ(FirstGLError(), 0u) << "a draw with an enabled 64-bit array must not raise an error";
+
+            const Image image = ReadPixels(target.width, target.height);
+            ASSERT_FALSE(image.Empty());
+            EXPECT_GT(image.At(target.width / 2, target.height / 2).g, 200)
+                << "the draw did not happen; the enabled 64-bit array must be dropped, not fatal";
+
+            glDisableVertexAttribArray(0);
+            glDisableVertexAttribArray(1);
+            glBindVertexArray(0);
+            glDeleteVertexArrays(1, &vao);
+            glDeleteBuffers(1, &positionBuffer);
+            glDeleteBuffers(1, &doubleBuffer);
+            BindDefaultFramebuffer();
+            DestroyColorFbo(target);
+            glUseProgram(0);
+            glDeleteProgram(program);
+            EXPECT_EQ(FirstGLError(), 0u);
+        }
+
     } // namespace
 } // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/ImageSizeAfterRespecScenario.cpp

@@ -0,0 +1,234 @@
+// MobileGL - MobileGL/MG_IntegrationTest/Scenarios/ImageSizeAfterRespecScenario.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// Scenario - A DRAW READS imageSize() AFTER THE IMAGE TEXTURE IS RE-SPECIFIED.
+//
+// KHR-GL43.shader_image_size.advanced-changeSize reduced to its mechanism. The application binds
+// a texture to an image unit ONCE, draws, then re-specifies that same texture with a new size
+// through glTexImage2D and draws again - without touching the image unit. GL says the unit
+// references the texture OBJECT, so the second draw must see the new dimensions.
+//
+// On Espryt it did not, and the reason is two facts meeting:
+//
+//   1. ES 3.1 only allows IMMUTABLE storage on an image unit, so the backend forces glTexStorage
+//      backing on any texture that reaches one (SyncTextureObjectToBackend's
+//      imageBindableStorageRequired). Immutable storage cannot be redefined, so a glTexImage2D
+//      that changes size or format has to MINT A NEW ES TEXTURE NAME.
+//   2. The draw path never re-issued glBindImageTexture. Image units were established eagerly,
+//      once, when the application called glBindImageTexture, and PrepareForDraw only ever
+//      re-synced SAMPLED textures - so the unit kept pointing at the deleted name and
+//      imageSize() reported whatever that stale binding still meant.
+//
+// A dispatch was never affected: PrepareForCompute has always swept the image units. This is a
+// draw-path scenario for exactly that reason - a compute-shaped case cannot see the defect.
+//
+// Both backends run it. Magma re-derives its image descriptors per draw and so was never wrong
+// here, which makes it the control: the two backends have to agree on what the second draw sees.
+
+#include <string>
+#include <vector>
+
+#include "../Harness/HeadlessGL.h"
+#include "../Harness/ScenarioFixture.h"
+
+#ifdef GLAPI
+#undef GLAPI
+#endif
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glcorearb.h>
+#undef GL_GLEXT_PROTOTYPES
+
+namespace MGITest {
+    namespace {
+
+        constexpr int kTargetSize = 8;
+
+        constexpr const char* kVS = R"(#version 430 core
+void main()
+{
+    // A single triangle that covers the whole target, with no vertex buffer at all: the
+    // scenario is about the image unit, so nothing else may be able to make it fail.
+    switch (gl_VertexID)
+    {
+      case 0: gl_Position = vec4(-1.0, -1.0, 0.0, 1.0); break;
+      case 1: gl_Position = vec4( 3.0, -1.0, 0.0, 1.0); break;
+      case 2: gl_Position = vec4(-1.0,  3.0, 0.0, 1.0); break;
+    }
+}
+)";
+
+        // Green when the image the unit currently holds has the size the application last gave
+        // it, red otherwise - the conformance case's own comparison, and its own colours.
+        constexpr const char* kFS = R"(#version 430 core
+layout(rgba8) readonly uniform image2D g_image;
+uniform ivec2 g_expected_size;
+layout(location = 0) out vec4 o_color;
+void main()
+{
+    o_color = (imageSize(g_image) == g_expected_size) ? vec4(0.0, 1.0, 0.0, 1.0) : vec4(1.0, 0.0, 0.0, 1.0);
+}
+)";
+
+        class ImageSizeAfterRespecScenario : public ScenarioTest {
+        protected:
+            void TearDown() override {
+                if (!Ready()) return;
+                glUseProgram(0);
+                glBindImageTexture(0, 0, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA8);
+                glBindFramebuffer(GL_FRAMEBUFFER, 0);
+                if (m_program != 0) glDeleteProgram(m_program);
+                if (m_fbo != 0) glDeleteFramebuffers(1, &m_fbo);
+                if (m_color != 0) glDeleteTextures(1, &m_color);
+                if (m_image != 0) glDeleteTextures(1, &m_image);
+                if (m_vao != 0) glDeleteVertexArrays(1, &m_vao);
+                m_program = m_fbo = m_color = m_image = m_vao = 0;
+                while (glGetError() != GL_NO_ERROR) {
+                }
+            }
+
+            // imageSize() needs a fragment-stage image uniform; a driver that serves none should
+            // skip rather than fail.
+            bool FragmentImagesAreUsable() const {
+                GLint maxImageUnits = 0;
+                GLint maxFragmentImageUniforms = 0;
+                glGetIntegerv(GL_MAX_IMAGE_UNITS, &maxImageUnits);
+                glGetIntegerv(GL_MAX_FRAGMENT_IMAGE_UNIFORMS, &maxFragmentImageUniforms);
+                while (glGetError() != GL_NO_ERROR) {
+                }
+                return maxImageUnits >= 1 && maxFragmentImageUniforms >= 1;
+            }
+
+            GLuint MakeProgram() {
+                const GLuint vs = glCreateShader(GL_VERTEX_SHADER);
+                const GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
+                glShaderSource(vs, 1, &kVS, nullptr);
+                glShaderSource(fs, 1, &kFS, nullptr);
+                glCompileShader(vs);
+                glCompileShader(fs);
+                for (const GLuint shader : {vs, fs}) {
+                    GLint compiled = GL_FALSE;
+                    glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+                    if (compiled == GL_FALSE) {
+                        char log[4096] = {};
+                        glGetShaderInfoLog(shader, sizeof(log) - 1, nullptr, log);
+                        ADD_FAILURE() << "a shader did not compile: " << log;
+                        glDeleteShader(vs);
+                        glDeleteShader(fs);
+                        return 0;
+                    }
+                }
+                const GLuint program = glCreateProgram();
+                glAttachShader(program, vs);
+                glAttachShader(program, fs);
+                glLinkProgram(program);
+                glDeleteShader(vs);
+                glDeleteShader(fs);
+                GLint linked = GL_FALSE;
+                glGetProgramiv(program, GL_LINK_STATUS, &linked);
+                if (linked == GL_FALSE) {
+                    char log[4096] = {};
+                    glGetProgramInfoLog(program, sizeof(log) - 1, nullptr, log);
+                    ADD_FAILURE() << "the program did not link: " << log;
+                    glDeleteProgram(program);
+                    return 0;
+                }
+                return program;
+            }
+
+            void MakeRenderTarget() {
+                glGenTextures(1, &m_color);
+                glBindTexture(GL_TEXTURE_2D, m_color);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+                glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, kTargetSize, kTargetSize, 0, GL_RGBA, GL_UNSIGNED_BYTE,
+                             nullptr);
+                glGenFramebuffers(1, &m_fbo);
+                glBindFramebuffer(GL_FRAMEBUFFER, m_fbo);
+                glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_color, 0);
+            }
+
+            // Draw once with `expected` pushed to the shader and report the centre pixel.
+            void DrawAndReadCentre(int expectedWidth, int expectedHeight, unsigned char (&centre)[4]) {
+                const GLint location = glGetUniformLocation(m_program, "g_expected_size");
+                ASSERT_NE(location, -1) << "the program has no g_expected_size uniform";
+                glUseProgram(m_program);
+                glUniform2i(location, expectedWidth, expectedHeight);
+                glViewport(0, 0, kTargetSize, kTargetSize);
+                glDisable(GL_SCISSOR_TEST);
+                glDisable(GL_DEPTH_TEST);
+                glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
+                glClear(GL_COLOR_BUFFER_BIT);
+                glDrawArrays(GL_TRIANGLES, 0, 3);
+                ASSERT_EQ(FirstGLError(), 0u) << "the draw left a GL error";
+
+                std::vector<unsigned char> pixels(static_cast<std::size_t>(kTargetSize) * kTargetSize * 4, 0);
+                glReadPixels(0, 0, kTargetSize, kTargetSize, GL_RGBA, GL_UNSIGNED_BYTE, pixels.data());
+                ASSERT_EQ(FirstGLError(), 0u) << "reading the target back errored";
+                const std::size_t offset =
+                    (static_cast<std::size_t>(kTargetSize / 2) * kTargetSize + kTargetSize / 2) * 4;
+                for (int i = 0; i < 4; ++i) {
+                    centre[i] = pixels[offset + static_cast<std::size_t>(i)];
+                }
+            }
+
+            GLuint m_program = 0;
+            GLuint m_fbo = 0;
+            GLuint m_color = 0;
+            GLuint m_image = 0;
+            GLuint m_vao = 0;
+        };
+
+    } // namespace
+
+    // The whole conformance shape: bind once, draw, re-specify the SAME texture smaller, draw
+    // again. The first draw is the control - it proves the binding and the shader work at all -
+    // and the second is the regression pin. Blue would mean the draw never ran; red means the
+    // image unit answered with the size the texture had BEFORE the re-spec.
+    TEST_F(ImageSizeAfterRespecScenario, ADrawSeesTheNewSizeOfARespecifiedImageTexture) {
+        if (!Ready()) return;
+        if (!FragmentImagesAreUsable()) GTEST_SKIP() << "no fragment-stage image uniform available";
+
+        m_program = MakeProgram();
+        if (m_program == 0) return;
+        glGenVertexArrays(1, &m_vao);
+        glBindVertexArray(m_vao);
+        MakeRenderTarget();
+        ASSERT_EQ(FirstGLError(), 0u) << "setting the render target up errored";
+
+        glGenTextures(1, &m_image);
+        glBindTexture(GL_TEXTURE_2D, m_image);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 32, 32, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+        glBindImageTexture(0, m_image, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA8);
+        ASSERT_EQ(FirstGLError(), 0u) << "binding the image texture errored";
+
+        unsigned char centre[4] = {0, 0, 0, 0};
+        DrawAndReadCentre(32, 32, centre);
+        EXPECT_EQ(static_cast<int>(centre[0]), 0) << "the FIRST draw already disagrees about imageSize(): got ("
+                                                  << static_cast<int>(centre[0]) << ", "
+                                                  << static_cast<int>(centre[1]) << ", "
+                                                  << static_cast<int>(centre[2]) << ")";
+        EXPECT_EQ(static_cast<int>(centre[1]), 255);
+
+        // The re-spec. The image unit is deliberately NOT re-bound: GL 4.6 core 8.26 says the
+        // unit references the texture object, so this alone has to be visible to the next draw.
+        glBindTexture(GL_TEXTURE_2D, m_image);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+        ASSERT_EQ(FirstGLError(), 0u) << "re-specifying the image texture errored";
+
+        DrawAndReadCentre(16, 16, centre);
+        EXPECT_EQ(static_cast<int>(centre[0]), 0)
+            << "after the re-spec the draw still sees the OLD image size; centre pixel was ("
+            << static_cast<int>(centre[0]) << ", " << static_cast<int>(centre[1]) << ", "
+            << static_cast<int>(centre[2]) << ")";
+        EXPECT_EQ(static_cast<int>(centre[1]), 255);
+    }
+
+} // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/ImageTargetKindScenario.cpp

@@ -374,6 +374,86 @@ namespace MGITest {
                 glUseProgram(0);
             }
 
+            // The same texture, bound four times over, varying nothing but `layered` and `layer`.
+            //
+            // GL 4.6 core 8.26 (and ES 3.2 8.22, word for word): "If the texture identified by
+            // texture does not have multiple layers or faces, the entire texture level is bound,
+            // regardless of the values of layered and layer." REGARDLESS means ignored - not
+            // clamped, and not an error - so every one of the four rows has to read the same texel
+            // out of a target that has no layers, including the two rows that name layer 1 on a
+            // texture whose only layer is 0. DirectGLES used to normalize `layered` and forward
+            // `layer` verbatim; Adreno honours the bogus layer by leaving the image unit reading
+            // zero, which is exactly the two rows KHR-GL42.bind_image_texture.single_layer failed.
+            //
+            // The bindings are checked back as well, because the fix depends on WHERE the
+            // normalization happens: the frontend shadow must keep echoing the application's own
+            // values (gl4cShaderImageLoadStoreTests' CheckBinding compares them exactly), and only
+            // the backend's driver call may drop the layer.
+            void RunNonLayerableLayerSweepCase(const TargetKind& kind) {
+                const GLuint program = MakeComputeProgram(SingleLoadSource(kind));
+                if (program == 0) return;
+                const GLuint texture = MakeTexture(kind, true);
+                if (texture == 0) return;
+
+                // A multisample texture has no TexSubImage, so MakeTexture leaves it unwritten and
+                // it is seeded the way the store cases do it - through a dispatch of its own.
+                const GLuint expected = kind.multisample ? kStoredValue : kFilledValue;
+                if (kind.multisample) {
+                    const GLuint storeProgram = MakeComputeProgram(SingleStoreSource(kind));
+                    if (storeProgram == 0) return;
+                    glBindImageTexture(0, texture, 0, GL_TRUE, 0, GL_READ_WRITE, GL_R32UI);
+                    glUseProgram(storeProgram);
+                    glUniform1i(0, 0);
+                    glDispatchCompute(1, 1, 1);
+                    glMemoryBarrier(GL_ALL_BARRIER_BITS);
+                    ASSERT_EQ(FirstGLError(), 0u) << kind.name << ": seeding the multisample texture errored";
+                }
+
+                const GLuint ssbo = MakeResultBuffer();
+                glUseProgram(program);
+                glUniform1i(0, 0);
+                ASSERT_EQ(FirstGLError(), 0u) << kind.name << ": assigning the image unit errored";
+
+                // glcBindImageTextureTests' own four rows, in its own order.
+                struct LayerRow {
+                    GLboolean layered;
+                    GLint layer;
+                };
+                static constexpr LayerRow kRows[] = {{GL_TRUE, 1}, {GL_TRUE, 0}, {GL_FALSE, 1}, {GL_FALSE, 0}};
+
+                for (const LayerRow& row : kRows) {
+                    const std::string where = std::string(kind.name) +
+                                              ": layered=" + (row.layered == GL_TRUE ? "TRUE" : "FALSE") +
+                                              " layer=" + std::to_string(row.layer);
+                    // Re-zeroed per row, so a row whose binding reads nothing cannot pass on the
+                    // previous row's answer.
+                    const GLuint zero = 0u;
+                    glBindBuffer(GL_SHADER_STORAGE_BUFFER, ssbo);
+                    glBufferSubData(GL_SHADER_STORAGE_BUFFER, 0, sizeof(GLuint), &zero);
+
+                    glBindImageTexture(0, texture, 0, row.layered, row.layer, GL_READ_ONLY, GL_R32UI);
+                    EXPECT_EQ(FirstGLError(), 0u) << where << ": glBindImageTexture errored";
+
+                    GLint reportedLayered = -1;
+                    GLint reportedLayer = -1;
+                    glGetIntegeri_v(GL_IMAGE_BINDING_LAYERED, 0, &reportedLayered);
+                    glGetIntegeri_v(GL_IMAGE_BINDING_LAYER, 0, &reportedLayer);
+                    EXPECT_EQ(reportedLayered, row.layered == GL_TRUE ? 1 : 0)
+                        << where << ": GL_IMAGE_BINDING_LAYERED stopped reporting the application's value";
+                    EXPECT_EQ(reportedLayer, row.layer)
+                        << where << ": GL_IMAGE_BINDING_LAYER stopped reporting the application's value";
+
+                    glDispatchCompute(1, 1, 1);
+                    glMemoryBarrier(GL_ALL_BARRIER_BITS);
+                    EXPECT_EQ(FirstGLError(), 0u) << where << ": the dispatch leaked a GL error";
+                    EXPECT_EQ(ReadResult(ssbo), expected)
+                        << where
+                        << ": the texel did not come back, so the binding named a layer the texture "
+                           "does not have instead of the whole level";
+                }
+                glUseProgram(0);
+            }
+
             std::vector<GLuint> m_programs;
             std::vector<GLuint> m_textures;
             std::vector<GLuint> m_buffers;
@@ -435,6 +515,31 @@ namespace MGITest {
 #undef MGL_DEFINE_LOAD_CASE
 #undef MGL_DEFINE_STORE_CASE
 
+    // ---- and the same texture bound four times, varying only layered/layer ---
+    //
+    // KHR-GL42.bind_image_texture.single_layer's sweep, on the kinds whose backend target has
+    // neither layers nor faces. Two of its four rows name layer 1 on a single-layer texture,
+    // which the spec says is to be ignored outright rather than honoured or rejected - and
+    // which DirectGLES used to forward to the ES driver as written.
+
+#define MGL_DEFINE_LAYER_SWEEP_CASE(CaseName, Kind)                                                             \
+    TEST_F(ImageTargetKindScenario, IgnoresLayerFor##CaseName) {                                                \
+        if (!Ready()) return;                                                                                   \
+        if (!ImagesAreUsable()) GTEST_SKIP() << "no compute image uniforms";                                    \
+        if ((Kind).multisample && !MultisampleImagesAreUsable()) {                                              \
+            GTEST_SKIP() << "GL_MAX_IMAGE_SAMPLES is 0, so the conformance case substitutes a plain 2D image "  \
+                            "here and never asks for a multisample one";                                        \
+        }                                                                                                       \
+        RunNonLayerableLayerSweepCase(Kind);                                                                    \
+    }
+
+    MGL_DEFINE_LAYER_SWEEP_CASE(Texture2D, kKind2D)
+    MGL_DEFINE_LAYER_SWEEP_CASE(Texture1D, kKind1D)
+    MGL_DEFINE_LAYER_SWEEP_CASE(TextureRectangle, kKindRect)
+    MGL_DEFINE_LAYER_SWEEP_CASE(Texture2DMultisample, kKind2DMS)
+
+#undef MGL_DEFINE_LAYER_SWEEP_CASE
+
     // ---- and all of them at once -------------------------------------------
     //
     // The conformance case's actual shape. The single-kind cases above cannot see a defect that

MobileGL/MG_IntegrationTest/Scenarios/IoBlockNameCollisionScenario.cpp

@@ -0,0 +1,389 @@
+// MobileGL - MobileGL/MG_IntegrationTest/Scenarios/IoBlockNameCollisionScenario.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// Scenario - ONE BLOCK NAME USED IN BOTH DIRECTIONS BY ONE STAGE STILL CARRIES ITS PAYLOAD.
+//
+// Desktop GLSL keeps SEPARATE name namespaces for input and output interface blocks, so a
+// single stage may legally write
+//
+//     in  TcsData { ... } tes_in[];
+//     out TcsData { ... } tes_out;
+//
+// The tessellation evaluation stage of both interface-block tests in
+// KHR-GL42/43.shading_language_420pack does exactly that, and MobileGL's backend used to
+// hand the shape straight through: SPIRV-Cross splits the namespace the same way glslang
+// does (block_input_names vs block_output_names) and re-emits BOTH blocks under the name
+// TcsData, so the generated ESSL declares two different blocks of one name in one shader.
+// Adreno's ES compiler keeps them apart. Mali's does not - the stage compiles, the program
+// links, and the evaluation stage's writes never reach the geometry stage, which is all 22
+// of that group's Mali failures and none of Adreno's or DirectVulkan's.
+//
+// Both cases below drive the SAME five-stage pipeline (vertex -> tessellation control ->
+// tessellation evaluation -> geometry -> fragment) and differ only in whether the
+// evaluation stage reuses one name. The distinct-name case is the negative control: it is
+// what says a red pixel in the colliding case is about the name and not about this machine's
+// tessellation, its geometry stage, or the block mechanism in general.
+//
+// Colour code, so a failure names its own cause:
+//   green  - the payload crossed all four stage boundaries, which is the pass.
+//   blue   - the clear colour: nothing was drawn at all (the program did not link, or the
+//            backend program was rejected and every draw became a no-op).
+//   red    - the pipeline ran but the plain (non-block) varying did not arrive, i.e. the
+//            failure is not about interface blocks.
+//   black  - the pipeline ran, the plain varying arrived, and the BLOCK payload came back
+//            zeroed or garbage. That is the defect this scenario exists for.
+//
+// llvmpipe and lavapipe run this faithfully but do NOT reproduce the original defect - the
+// aliasing is a Mali ES compiler behaviour. Read a green run here as "the rename did not
+// break the ordinary path"; the claim it pins on the device is the CTS group above.
+
+#include <string>
+#include <vector>
+
+#include "../Harness/HeadlessGL.h"
+#include "../Harness/ScenarioFixture.h"
+
+#ifdef GLAPI
+#undef GLAPI
+#endif
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glcorearb.h>
+#undef GL_GLEXT_PROTOTYPES
+
+namespace MGITest {
+    namespace {
+
+        // The payload starts here and is copied, unmodified, through every block below.
+        const char* const kVertexSource = R"(#version 420 core
+out VsData {
+    vec4 payload;
+} vs_out;
+void main()
+{
+    vs_out.payload = vec4(0.0, 1.0, 0.0, 1.0);
+    gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
+}
+)";
+
+        const char* const kTessControlSource = R"(#version 420 core
+layout(vertices = 1) out;
+in VsData {
+    vec4 payload;
+} tcs_in[];
+out TcsData {
+    vec4 payload;
+} tcs_out[];
+void main()
+{
+    tcs_out[gl_InvocationID].payload = tcs_in[gl_InvocationID].payload;
+    gl_TessLevelOuter[0] = 1.0;
+    gl_TessLevelOuter[1] = 1.0;
+    gl_TessLevelOuter[2] = 1.0;
+    gl_TessLevelOuter[3] = 1.0;
+    gl_TessLevelInner[0] = 1.0;
+    gl_TessLevelInner[1] = 1.0;
+}
+)";
+
+        // THE CASE UNDER TEST: one name, both directions, in one stage.
+        const char* const kCollidingTessEvalSource = R"(#version 420 core
+layout(isolines, point_mode) in;
+in TcsData {
+    vec4 payload;
+} tes_in[];
+out TcsData {
+    vec4 payload;
+} tes_out;
+out float tes_gs_alive;
+void main()
+{
+    tes_out.payload = tes_in[0].payload;
+    tes_gs_alive = 1.0;
+}
+)";
+
+        // The negative control: byte-identical but for the output block's name.
+        const char* const kDistinctTessEvalSource = R"(#version 420 core
+layout(isolines, point_mode) in;
+in TcsData {
+    vec4 payload;
+} tes_in[];
+out TesData {
+    vec4 payload;
+} tes_out;
+out float tes_gs_alive;
+void main()
+{
+    tes_out.payload = tes_in[0].payload;
+    tes_gs_alive = 1.0;
+}
+)";
+
+        // One geometry source per evaluation stage, because the block it consumes is named
+        // after the block the evaluation stage produced.
+        const char* const kCollidingGeometrySource = R"(#version 420 core
+layout(points) in;
+layout(triangle_strip, max_vertices = 4) out;
+in TcsData {
+    vec4 payload;
+} gs_in[];
+in float tes_gs_alive[];
+out GsData {
+    vec4 payload;
+} gs_out;
+out float gs_fs_alive;
+void EmitCorner(vec2 corner)
+{
+    gs_out.payload = gs_in[0].payload;
+    gs_fs_alive = tes_gs_alive[0];
+    gl_Position = vec4(corner, 0.0, 1.0);
+    EmitVertex();
+}
+void main()
+{
+    EmitCorner(vec2(-1.0, -1.0));
+    EmitCorner(vec2(-1.0,  1.0));
+    EmitCorner(vec2( 1.0, -1.0));
+    EmitCorner(vec2( 1.0,  1.0));
+}
+)";
+
+        const char* const kDistinctGeometrySource = R"(#version 420 core
+layout(points) in;
+layout(triangle_strip, max_vertices = 4) out;
+in TesData {
+    vec4 payload;
+} gs_in[];
+in float tes_gs_alive[];
+out GsData {
+    vec4 payload;
+} gs_out;
+out float gs_fs_alive;
+void EmitCorner(vec2 corner)
+{
+    gs_out.payload = gs_in[0].payload;
+    gs_fs_alive = tes_gs_alive[0];
+    gl_Position = vec4(corner, 0.0, 1.0);
+    EmitVertex();
+}
+void main()
+{
+    EmitCorner(vec2(-1.0, -1.0));
+    EmitCorner(vec2(-1.0,  1.0));
+    EmitCorner(vec2( 1.0, -1.0));
+    EmitCorner(vec2( 1.0,  1.0));
+}
+)";
+
+        // Red when the PLAIN varying did not arrive, so "the pipeline is broken" and "the
+        // block payload is broken" cannot be confused for one another.
+        const char* const kFragmentSource = R"(#version 420 core
+in GsData {
+    vec4 payload;
+} fs_in;
+in float gs_fs_alive;
+out vec4 fragColor;
+void main()
+{
+    fragColor = gs_fs_alive > 0.5 ? fs_in.payload : vec4(1.0, 0.0, 0.0, 1.0);
+}
+)";
+
+        class IoBlockNameCollisionScenario : public ScenarioTest {
+        protected:
+            void SetUp() override {
+                ScenarioTest::SetUp();
+                if (!Ready()) return;
+                glGenVertexArrays(1, &m_vao);
+                glBindVertexArray(m_vao);
+                if (!BackendHostsTessellationAndGeometry()) {
+                    GTEST_SKIP() << "no tessellation/geometry stages on " << Gl().BackendName() << " ("
+                                 << Gl().RendererString() << "); there is no five-stage pipeline to "
+                                 << "carry a block through";
+                }
+            }
+
+            void TearDown() override {
+                if (!Ready()) return;
+                glUseProgram(0);
+                for (const GLuint program : m_programs) {
+                    glDeleteProgram(program);
+                }
+                m_programs.clear();
+                glBindVertexArray(0);
+                if (m_vao != 0) glDeleteVertexArrays(1, &m_vao);
+                m_vao = 0;
+            }
+
+            // GL_MAX_TESS_GEN_LEVEL is a real backend answer, not a frontend constant: it
+            // reads 0 on a DirectGLES driver without GL_EXT_tessellation_shader and on a
+            // DirectVulkan device without the tessellationShader feature. There is no
+            // five-stage pipeline to assert about on such a stack.
+            static bool BackendHostsTessellationAndGeometry() {
+                GLint maxTessGenLevel = 0;
+                glGetIntegerv(GL_MAX_TESS_GEN_LEVEL, &maxTessGenLevel);
+                GLint maxGeometryOutputVertices = 0;
+                glGetIntegerv(GL_MAX_GEOMETRY_OUTPUT_VERTICES, &maxGeometryOutputVertices);
+                while (glGetError() != GL_NO_ERROR) {
+                }
+                return maxTessGenLevel >= 1 && maxGeometryOutputVertices >= 4;
+            }
+
+            GLuint BuildPipeline(const char* tessEvalSource, const char* geometrySource) {
+                const GLenum stages[] = {GL_VERTEX_SHADER, GL_TESS_CONTROL_SHADER,
+                                         GL_TESS_EVALUATION_SHADER, GL_GEOMETRY_SHADER,
+                                         GL_FRAGMENT_SHADER};
+                const char* const sources[] = {kVertexSource, kTessControlSource, tessEvalSource,
+                                               geometrySource, kFragmentSource};
+
+                GLuint shaders[5] = {0, 0, 0, 0, 0};
+                bool ok = true;
+                for (int i = 0; i < 5; ++i) {
+                    shaders[i] = glCreateShader(stages[i]);
+                    glShaderSource(shaders[i], 1, &sources[i], nullptr);
+                    glCompileShader(shaders[i]);
+                    GLint compiled = 0;
+                    glGetShaderiv(shaders[i], GL_COMPILE_STATUS, &compiled);
+                    if (!compiled) {
+                        m_buildLog = InfoLog(shaders[i], true);
+                        ok = false;
+                        break;
+                    }
+                }
+                if (!ok) {
+                    for (const GLuint shader : shaders) {
+                        if (shader != 0) glDeleteShader(shader);
+                    }
+                    return 0;
+                }
+
+                const GLuint program = glCreateProgram();
+                for (const GLuint shader : shaders) {
+                    glAttachShader(program, shader);
+                }
+                glLinkProgram(program);
+                GLint linked = 0;
+                glGetProgramiv(program, GL_LINK_STATUS, &linked);
+                for (const GLuint shader : shaders) {
+                    glDeleteShader(shader);
+                }
+                if (!linked) {
+                    m_buildLog = InfoLog(program, false);
+                    glDeleteProgram(program);
+                    return 0;
+                }
+                m_programs.push_back(program);
+                return program;
+            }
+
+            // Clears to BLUE, so "the draw painted nothing" is a colour of its own rather
+            // than something that could be mistaken for a zeroed payload.
+            Rgba8 DrawAndReadCentre(GLuint program) const {
+                glViewport(0, 0, Gl().Width(), Gl().Height());
+                glClearColor(0.0f, 0.0f, 1.0f, 1.0f);
+                glClear(GL_COLOR_BUFFER_BIT);
+                glUseProgram(program);
+                glPatchParameteri(GL_PATCH_VERTICES, 1);
+                glDrawArrays(GL_PATCHES, 0, 1);
+
+                Rgba8 pixel{};
+                glReadPixels(Gl().Width() / 2, Gl().Height() / 2, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
+                return pixel;
+            }
+
+            static bool IsGreen(const Rgba8& pixel) {
+                return pixel.r < 64 && pixel.g > 192 && pixel.b < 64;
+            }
+
+            const std::string& BuildLog() const { return m_buildLog; }
+
+            static GLenum FirstGLError() {
+                const GLenum first = glGetError();
+                while (glGetError() != GL_NO_ERROR) {
+                }
+                return first;
+            }
+
+        private:
+            static std::string InfoLog(GLuint object, bool isShader) {
+                GLint length = 0;
+                if (isShader) {
+                    glGetShaderiv(object, GL_INFO_LOG_LENGTH, &length);
+                } else {
+                    glGetProgramiv(object, GL_INFO_LOG_LENGTH, &length);
+                }
+                std::vector<char> log(static_cast<std::size_t>(length > 1 ? length : 1), '\0');
+                if (isShader) {
+                    glGetShaderInfoLog(object, static_cast<GLsizei>(log.size()), nullptr, log.data());
+                } else {
+                    glGetProgramInfoLog(object, static_cast<GLsizei>(log.size()), nullptr, log.data());
+                }
+                return std::string(log.data());
+            }
+
+            GLuint m_vao = 0;
+            std::vector<GLuint> m_programs;
+            std::string m_buildLog;
+        };
+
+        // The negative control, and it runs first on purpose: if this one is not green there
+        // is nothing to conclude from the case below it.
+        //
+        // It is also the CALIBRATION. GL_MAX_TESS_GEN_LEVEL answers for the tessellation
+        // stages honestly, but nothing MobileGL reports answers for the geometry stage the
+        // same way (GL_MAX_GEOMETRY_* are frontend constants and an ES driver may legitimately
+        // report zero geometry storage blocks while having geometry shaders), so a stack that
+        // cannot build a five-stage program at all is recognised here, by trying.
+        TEST_F(IoBlockNameCollisionScenario, DistinctlyNamedBlocksCarryThePayloadThroughFiveStages) {
+            if (!Ready()) return;
+
+            const GLuint program = BuildPipeline(kDistinctTessEvalSource, kDistinctGeometrySource);
+            if (program == 0) {
+                GTEST_SKIP() << "this stack cannot build a five-stage tessellation+geometry program on "
+                             << Gl().BackendName() << ", so there is no block to carry through: "
+                             << BuildLog();
+            }
+
+            const Rgba8 centre = DrawAndReadCentre(program);
+            EXPECT_EQ(FirstGLError(), 0u);
+            EXPECT_TRUE(IsGreen(centre)) << "the control pipeline did not deliver its payload: " << centre;
+        }
+
+        TEST_F(IoBlockNameCollisionScenario, OneBlockNameInBothDirectionsStillCarriesThePayload) {
+            if (!Ready()) return;
+
+            // Same calibration as the case above, and for the same reason: a five-stage program
+            // this stack cannot build at all is not evidence about block names. Only once the
+            // DISTINCT-name build succeeds does a failure of the colliding one mean something.
+            if (BuildPipeline(kDistinctTessEvalSource, kDistinctGeometrySource) == 0) {
+                GTEST_SKIP() << "this stack cannot build a five-stage tessellation+geometry program on "
+                             << Gl().BackendName() << ", so there is no block to carry through: "
+                             << BuildLog();
+            }
+
+            // Legal desktop GLSL: input and output block names live in separate namespaces, so
+            // the evaluation stage below declares TcsData twice and must still compile. The
+            // control above having built is what makes this assertion about the NAME.
+            const GLuint program = BuildPipeline(kCollidingTessEvalSource, kCollidingGeometrySource);
+            ASSERT_NE(program, 0u)
+                << "an interface block name reused across the two directions of one stage is legal "
+                   "desktop GLSL, but the program did not build: "
+                << BuildLog();
+
+            const Rgba8 centre = DrawAndReadCentre(program);
+            EXPECT_EQ(FirstGLError(), 0u);
+            EXPECT_TRUE(IsGreen(centre))
+                << "the payload did not survive the stage that names its input and output block "
+                   "the same: "
+                << centre << " (blue: nothing drew; red: the plain varying was lost too; black: "
+                             "the block arrived empty)";
+        }
+
+    } // namespace
+} // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/LayeredTextureReadbackScenario.cpp

@@ -0,0 +1,286 @@
+// MobileGL - MobileGL/MG_IntegrationTest/Scenarios/LayeredTextureReadbackScenario.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// Scenario - READING EVERY LAYER OF A 1D-ARRAY / CUBE-MAP-ARRAY LEVEL BACK.
+//
+// glGetTexImage has no ES equivalent, so Espryt serves it by attaching the level to a scratch
+// READ framebuffer and reading it with glReadPixels. Two of the targets it has to answer for do
+// not fit that shape the way the others do, and both came back as zeroes in
+// KHR-GL4x.shader_image_load_store.basic-allTargets-* and .non-layered_binding:
+//
+//   * GL_TEXTURE_1D_ARRAY carries its LAYERS in the state-side height - that is what
+//     glTexImage2D(GL_TEXTURE_1D_ARRAY, w, layers) means - while the ES texture behind it is a 2D
+//     array of height 1 with the layers in depth. The readback used the state-side shape, so it
+//     asked layer 0 for a `layers`-row rectangle that layer does not have: row 0 was the only one
+//     that could be right, and everything past it was whatever reading outside an attachment
+//     produces.
+//   * GL_TEXTURE_CUBE_MAP_ARRAY has no glFramebufferTexture2D target token at all, so the 2D
+//     attach it used to take errored, the scratch FBO stayed incomplete, and every read fell
+//     through to the CPU shadow - which holds what was UPLOADED, i.e. the seed, not what the
+//     shader stored.
+//
+// Both cases store from a compute dispatch (so the only copy of the data is the GPU one and a
+// stale shadow cannot pass) and then read the whole level back in one glGetTexImage, checking
+// every layer separately so a failure names which one. r32ui throughout: it is a core GLSL ES
+// image format, so nothing here can be confused with the missing-format story that
+// ImageFormatQualifierScenario covers.
+//
+// Magma reads these back through its own path and is unaffected by the ES attachment rules, so
+// both cases run on both backends and must agree.
+
+#include <cstddef>
+#include <string>
+#include <vector>
+
+#include "../Harness/HeadlessGL.h"
+#include "../Harness/ScenarioFixture.h"
+
+#ifdef GLAPI
+#undef GLAPI
+#endif
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glcorearb.h>
+#undef GL_GLEXT_PROTOTYPES
+
+namespace MGITest {
+    namespace {
+
+        constexpr int kExtent = 4;
+        constexpr int kArrayLayers = 3;     // enough that "layer 0 only" is visibly wrong
+        constexpr int kCubeLayerFaces = 12; // two cubes, which is what the conformance case uses
+        // A value no store writes, so "the store never landed" and "the store wrote the wrong
+        // thing" cannot be confused - and so a readback served from the stale CPU shadow is
+        // recognisable on sight.
+        constexpr GLuint kSeed = 0xFEEDBEEFu;
+        // Deliberately not 0: the unit has to travel through glUniform1i and be baked into the
+        // generated ESSL, so a defect there cannot hide behind the default.
+        constexpr GLint kImageUnit = 1;
+
+        GLuint Expected1DArrayTexel(int x, int layer) {
+            return 1000u + static_cast<GLuint>(layer) * 100u + static_cast<GLuint>(x);
+        }
+
+        GLuint ExpectedCubeArrayTexel(int x, int y, int layerFace) {
+            return 1000u + static_cast<GLuint>(layerFace) * 100u + static_cast<GLuint>(y) * 10u +
+                   static_cast<GLuint>(x);
+        }
+
+        // One invocation per texel, and the value it writes is a function of its coordinate - so
+        // a layer read from the wrong slice does not merely differ, it says which slice it came
+        // from.
+        const char* k1DArrayStoreSource = R"(#version 430 core
+
+layout (local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+
+layout (r32ui) writeonly uniform uimage1DArray uni_image;
+
+void main()
+{
+    uint x = gl_GlobalInvocationID.x;
+    uint layer = gl_GlobalInvocationID.z;
+    imageStore(uni_image, ivec2(int(x), int(layer)), uvec4(1000u + layer * 100u + x, 0u, 0u, 0u));
+}
+)";
+
+        const char* kCubeArrayStoreSource = R"(#version 430 core
+
+layout (local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+
+layout (r32ui) writeonly uniform uimageCubeArray uni_image;
+
+void main()
+{
+    uint x = gl_GlobalInvocationID.x;
+    uint y = gl_GlobalInvocationID.y;
+    uint layerFace = gl_GlobalInvocationID.z;
+    imageStore(uni_image, ivec3(int(x), int(y), int(layerFace)),
+               uvec4(1000u + layerFace * 100u + y * 10u + x, 0u, 0u, 0u));
+}
+)";
+
+        class LayeredTextureReadbackScenario : public ScenarioTest {
+        protected:
+            void TearDown() override {
+                if (!Ready()) return;
+                glUseProgram(0);
+                for (GLuint p : m_programs) glDeleteProgram(p);
+                for (GLuint t : m_textures) glDeleteTextures(1, &t);
+                m_programs.clear();
+                m_textures.clear();
+                GLint maxImageUnits = 0;
+                glGetIntegerv(GL_MAX_IMAGE_UNITS, &maxImageUnits);
+                for (GLint unit = 0; unit < maxImageUnits; ++unit) {
+                    glBindImageTexture(static_cast<GLuint>(unit), 0, 0, GL_FALSE, 0, GL_READ_ONLY, GL_R32UI);
+                }
+                while (glGetError() != GL_NO_ERROR) {
+                }
+            }
+
+            bool ImagesAreUsable() const {
+                GLint maxImageUnits = 0;
+                glGetIntegerv(GL_MAX_IMAGE_UNITS, &maxImageUnits);
+                GLint maxComputeImageUniforms = 0;
+                glGetIntegerv(GL_MAX_COMPUTE_IMAGE_UNIFORMS, &maxComputeImageUniforms);
+                while (glGetError() != GL_NO_ERROR) {
+                }
+                return maxImageUnits > kImageUnit && maxComputeImageUniforms >= 1;
+            }
+
+            GLuint MakeComputeProgram(const char* source) {
+                const GLuint shader = glCreateShader(GL_COMPUTE_SHADER);
+                glShaderSource(shader, 1, &source, nullptr);
+                glCompileShader(shader);
+                GLint compiled = GL_FALSE;
+                glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
+                if (compiled == GL_FALSE) {
+                    char log[4096] = {};
+                    glGetShaderInfoLog(shader, sizeof(log) - 1, nullptr, log);
+                    ADD_FAILURE() << "the compute shader did not compile: " << log;
+                    glDeleteShader(shader);
+                    return 0;
+                }
+                const GLuint program = glCreateProgram();
+                m_programs.push_back(program);
+                glAttachShader(program, shader);
+                glLinkProgram(program);
+                glDeleteShader(shader);
+                GLint linked = GL_FALSE;
+                glGetProgramiv(program, GL_LINK_STATUS, &linked);
+                if (linked == GL_FALSE) {
+                    char log[4096] = {};
+                    glGetProgramInfoLog(program, sizeof(log) - 1, nullptr, log);
+                    ADD_FAILURE() << "the compute program did not link: " << log;
+                    return 0;
+                }
+                return program;
+            }
+
+            GLuint TrackTexture() {
+                GLuint texture = 0;
+                glGenTextures(1, &texture);
+                m_textures.push_back(texture);
+                return texture;
+            }
+
+            // layered = GL_TRUE, i.e. the whole level: that is what makes every layer reachable
+            // from one dispatch, and it is what glBindImageTextures is specified to pass.
+            bool DispatchStore(GLuint program, GLuint texture, GLsizei groupsX, GLsizei groupsY, GLsizei groupsZ) {
+                glBindImageTexture(static_cast<GLuint>(kImageUnit), texture, 0, GL_TRUE, 0, GL_WRITE_ONLY, GL_R32UI);
+                if (const GLenum error = FirstGLError()) {
+                    ADD_FAILURE() << "glBindImageTexture errored with " << GLErrorName(error);
+                    return false;
+                }
+                glUseProgram(program);
+                const GLint location = glGetUniformLocation(program, "uni_image");
+                if (location < 0) {
+                    ADD_FAILURE() << "the image uniform was not reflected";
+                    return false;
+                }
+                glUniform1i(location, kImageUnit);
+                if (const GLenum error = FirstGLError()) {
+                    ADD_FAILURE() << "assigning the image unit errored with " << GLErrorName(error);
+                    return false;
+                }
+                glDispatchCompute(groupsX, groupsY, groupsZ);
+                glMemoryBarrier(GL_ALL_BARRIER_BITS);
+                glUseProgram(0);
+                if (const GLenum error = FirstGLError()) {
+                    ADD_FAILURE() << "the dispatch errored with " << GLErrorName(error);
+                    return false;
+                }
+                return true;
+            }
+
+            std::vector<GLuint> m_programs;
+            std::vector<GLuint> m_textures;
+        };
+
+        // The 1D-array half. A layer past the first is the whole test: layer 0 lines up with the
+        // ES image's only row whichever way the axes are read, so a readback that never swapped
+        // them still got it right and only the deeper layers came back wrong.
+        TEST_F(LayeredTextureReadbackScenario, GetTexImageReturnsEveryLayerOfA1DArray) {
+            if (!Ready()) return;
+            if (!ImagesAreUsable()) GTEST_SKIP() << "no compute image uniforms";
+
+            const GLuint program = MakeComputeProgram(k1DArrayStoreSource);
+            if (program == 0) return;
+
+            const GLuint texture = TrackTexture();
+            glBindTexture(GL_TEXTURE_1D_ARRAY, texture);
+            glTexParameteri(GL_TEXTURE_1D_ARRAY, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+            glTexParameteri(GL_TEXTURE_1D_ARRAY, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+            const std::vector<GLuint> seed(static_cast<std::size_t>(kExtent) * kArrayLayers, kSeed);
+            glTexImage2D(GL_TEXTURE_1D_ARRAY, 0, GL_R32UI, kExtent, kArrayLayers, 0, GL_RED_INTEGER, GL_UNSIGNED_INT,
+                         seed.data());
+            ASSERT_EQ(FirstGLError(), 0u) << "creating the R32UI 1D-array texture errored";
+
+            if (!DispatchStore(program, texture, kExtent, 1, kArrayLayers)) return;
+
+            std::vector<GLuint> texels(seed.size(), 0u);
+            glBindTexture(GL_TEXTURE_1D_ARRAY, texture);
+            glGetTexImage(GL_TEXTURE_1D_ARRAY, 0, GL_RED_INTEGER, GL_UNSIGNED_INT, texels.data());
+            ASSERT_EQ(FirstGLError(), 0u) << "reading the 1D-array level back errored";
+
+            // GL hands a 1D array back as a plain two-dimensional image whose ROWS are the
+            // layers, so the destination index is layer * width + x.
+            for (int layer = 0; layer < kArrayLayers; ++layer) {
+                for (int x = 0; x < kExtent; ++x) {
+                    const std::size_t index = static_cast<std::size_t>(layer) * kExtent + x;
+                    EXPECT_EQ(texels[index], Expected1DArrayTexel(x, layer))
+                        << "layer " << layer << " texel " << x << " read back "
+                        << (texels[index] == kSeed ? "the seed (the store never reached it, or the readback came "
+                                                     "from the stale CPU shadow)"
+                                                   : "an unexpected value");
+                }
+            }
+        }
+
+        // The cube-map-array half. glFramebufferTexture2D has no token for the target, so the
+        // scratch FBO used to stay incomplete and every read - including layer 0 - was answered
+        // from the CPU shadow; the seed is what makes that visible rather than merely wrong.
+        TEST_F(LayeredTextureReadbackScenario, GetTexImageReturnsEveryLayerFaceOfACubeMapArray) {
+            if (!Ready()) return;
+            if (!ImagesAreUsable()) GTEST_SKIP() << "no compute image uniforms";
+
+            const GLuint program = MakeComputeProgram(kCubeArrayStoreSource);
+            if (program == 0) return;
+
+            const GLuint texture = TrackTexture();
+            glBindTexture(GL_TEXTURE_CUBE_MAP_ARRAY, texture);
+            glTexParameteri(GL_TEXTURE_CUBE_MAP_ARRAY, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+            glTexParameteri(GL_TEXTURE_CUBE_MAP_ARRAY, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+            const std::vector<GLuint> seed(static_cast<std::size_t>(kExtent) * kExtent * kCubeLayerFaces, kSeed);
+            glTexImage3D(GL_TEXTURE_CUBE_MAP_ARRAY, 0, GL_R32UI, kExtent, kExtent, kCubeLayerFaces, 0, GL_RED_INTEGER,
+                         GL_UNSIGNED_INT, seed.data());
+            ASSERT_EQ(FirstGLError(), 0u) << "creating the R32UI cube-map-array texture errored";
+
+            if (!DispatchStore(program, texture, kExtent, kExtent, kCubeLayerFaces)) return;
+
+            std::vector<GLuint> texels(seed.size(), 0u);
+            glBindTexture(GL_TEXTURE_CUBE_MAP_ARRAY, texture);
+            glGetTexImage(GL_TEXTURE_CUBE_MAP_ARRAY, 0, GL_RED_INTEGER, GL_UNSIGNED_INT, texels.data());
+            ASSERT_EQ(FirstGLError(), 0u) << "reading the cube-map-array level back errored";
+
+            for (int layerFace = 0; layerFace < kCubeLayerFaces; ++layerFace) {
+                for (int y = 0; y < kExtent; ++y) {
+                    for (int x = 0; x < kExtent; ++x) {
+                        const std::size_t index =
+                            (static_cast<std::size_t>(layerFace) * kExtent + y) * kExtent + x;
+                        EXPECT_EQ(texels[index], ExpectedCubeArrayTexel(x, y, layerFace))
+                            << "layer-face " << layerFace << " texel (" << x << ", " << y << ") read back "
+                            << (texels[index] == kSeed ? "the seed (the store never reached it, or the readback "
+                                                         "came from the stale CPU shadow)"
+                                                       : "an unexpected value");
+                    }
+                }
+            }
+        }
+
+    } // namespace
+} // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/PackedWordReadbackScenario.cpp

@@ -0,0 +1,220 @@
+// MobileGL - MobileGL/MG_IntegrationTest/Scenarios/PackedWordReadbackScenario.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// glGetTexImage of a 32-bit packed format read with its OWN client type owes the application the
+// words the image HOLDS, and KHR-GL43.copy_image compares exactly those words. Two routes used to
+// answer, and both are wrong for a level glCopyImageSubData wrote:
+//
+//   * the colour-attachment route reads GL_RGBA/GL_FLOAT and re-encodes, which canonicalizes an
+//     RGB9_E5 shared exponent and collapses an R11F_G11F_B10F NaN payload to 1;
+//   * the CPU shadow only holds what was UPLOADED, and the mirror that replays a copy into it
+//     declines - silently - for a renderbuffer source, which has no shadow to mirror from.
+//
+// Both are pinned here with words the CTS itself uses, because both failures are invisible to a
+// value comparison: every assertion below is on BITS that decode to the very value the wrong
+// answer also decodes to.
+//
+// The fix is a raw-word route (DirectGLES::ReadPackedLevelWordsViaScratch: copy the level into a
+// scratch GL_R32UI image, read that back as unsigned integers), and DirectVulkan reaches the same
+// place through PackReadbackToClientOrPbo's raw-word branch over the staging bytes - so these
+// scenarios are backend-agnostic on purpose.
+
+#include <cstddef>
+#include <ios>
+#include <vector>
+
+#include "../Harness/HeadlessGL.h"
+#include "../Harness/ScenarioFixture.h"
+
+#ifdef GLAPI
+#undef GLAPI
+#endif
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glcorearb.h>
+#undef GL_GLEXT_PROTOTYPES
+
+namespace MGITest {
+    namespace {
+
+        constexpr GLsizei kExtent = 4;
+
+        // The non-canonical RGB9_E5 word KHR-GL43.copy_image writes: R=0, G=0, B mantissa 63,
+        // shared exponent 31, i.e. the value 8064, which the spec's own encoder would emit as
+        // 0xe7e00000 instead. Anything that decodes and re-encodes hands back the canonical word.
+        //
+        // Reinterpreted in the destination of an RGB9_E5 -> R11F_G11F_B10F copy it is R=0,
+        // G=1920, B=995 - and B's 5-bit exponent is all ones with a nonzero mantissa, i.e. a NaN
+        // whose payload 3 does not survive a float32 round trip (it comes back as the canonical
+        // payload 1, B=993, word 0xf87c0000). The two defects therefore land on the same word.
+        constexpr GLuint kRgb9E5Word = 0xf8fc0000u;
+
+        // The R11F_G11F_B10F word the same test pairs with it: R=0, G=0, B = exponent 12,
+        // mantissa 0 = 0.125. As an RGB9_E5 word it is all-zero channels with a shared exponent of
+        // 12, which the canonical encoder would write as 0x00000000 - so a decode/re-encode of THIS
+        // one loses every bit that distinguishes it.
+        constexpr GLuint kR11fG11fB10fWord = 0x60000000u;
+
+        class PackedWordReadbackScenario : public ScenarioTest {
+        protected:
+            void SetUp() override {
+                ScenarioTest::SetUp();
+                if (!Ready()) return;
+                DrainErrors();
+            }
+
+            void TearDown() override {
+                if (!Ready()) return;
+                DeleteObjects();
+                DrainErrors();
+                ScenarioTest::TearDown();
+            }
+
+            static void DrainErrors() {
+                for (int i = 0; i < 16 && glGetError() != GL_NO_ERROR; ++i) {
+                }
+            }
+
+            void DeleteObjects() {
+                if (m_src != 0) glDeleteTextures(1, &m_src);
+                if (m_dst != 0) glDeleteTextures(1, &m_dst);
+                if (m_rbo != 0) glDeleteRenderbuffers(1, &m_rbo);
+                m_src = 0;
+                m_dst = 0;
+                m_rbo = 0;
+            }
+
+            // A complete single-level texture whose every texel holds `word`, uploaded through the
+            // packed client type so the stored bits are the client's bits and nothing has had a
+            // chance to re-encode them.
+            GLuint MakePackedTexture(GLenum internalFormat, GLenum type, GLuint word) {
+                const std::vector<GLuint> words(static_cast<std::size_t>(kExtent) * kExtent, word);
+                GLuint texture = 0;
+                glGenTextures(1, &texture);
+                glBindTexture(GL_TEXTURE_2D, texture);
+                glTexImage2D(GL_TEXTURE_2D, 0, static_cast<GLint>(internalFormat), kExtent, kExtent, 0, GL_RGB, type,
+                             words.data());
+                // What Utils::makeTextureComplete does in the conformance cases, and what
+                // glCopyImageSubData requires of both endpoints.
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+                glBindTexture(GL_TEXTURE_2D, 0);
+                return texture;
+            }
+
+            // Every texel of level 0, as raw client words.
+            std::vector<GLuint> ReadPackedWords(GLuint texture, GLenum type) {
+                std::vector<GLuint> words(static_cast<std::size_t>(kExtent) * kExtent, 0xDEADBEEFu);
+                glBindTexture(GL_TEXTURE_2D, texture);
+                glGetTexImage(GL_TEXTURE_2D, 0, GL_RGB, type, words.data());
+                glBindTexture(GL_TEXTURE_2D, 0);
+                return words;
+            }
+
+            // The copy under test. Returns the error it raised so a driver that cannot perform the
+            // move at all can skip rather than fail: the point of these cases is which BITS come
+            // back, and there are none to compare if the copy never happened.
+            GLenum CopyWholeImage(GLuint srcName, GLenum srcTarget, GLuint dstName, GLenum dstTarget) {
+                DrainErrors();
+                glCopyImageSubData(srcName, srcTarget, 0, 0, 0, 0, dstName, dstTarget, 0, 0, 0, 0, kExtent, kExtent,
+                                   1);
+                const GLenum error = glGetError();
+                EXPECT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR)) << "the copy recorded more than one error";
+                return error;
+            }
+
+            static void ExpectEveryTexel(const std::vector<GLuint>& words, GLuint expected, const char* what) {
+                for (std::size_t i = 0; i < words.size(); ++i) {
+                    ASSERT_EQ(words[i], expected)
+                        << what << ": texel " << i << " read 0x" << std::hex << words[i] << ", expected 0x"
+                        << expected;
+                }
+            }
+
+            GLuint m_src = 0;
+            GLuint m_dst = 0;
+            GLuint m_rbo = 0;
+        };
+
+        // The control that has to hold before either regression means anything: a packed word
+        // uploaded and read straight back must be the SAME word, not merely the same colour.
+        TEST_F(PackedWordReadbackScenario, AnUploadedPackedWordReadsBackVerbatim) {
+            if (!Ready()) GTEST_SKIP();
+
+            m_src = MakePackedTexture(GL_RGB9_E5, GL_UNSIGNED_INT_5_9_9_9_REV, kRgb9E5Word);
+            ASSERT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR)) << "RGB9_E5 upload";
+            ExpectEveryTexel(ReadPackedWords(m_src, GL_UNSIGNED_INT_5_9_9_9_REV), kRgb9E5Word, "RGB9_E5 round trip");
+
+            m_dst = MakePackedTexture(GL_R11F_G11F_B10F, GL_UNSIGNED_INT_10F_11F_11F_REV, kR11fG11fB10fWord);
+            ASSERT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR)) << "R11F_G11F_B10F upload";
+            ExpectEveryTexel(ReadPackedWords(m_dst, GL_UNSIGNED_INT_10F_11F_11F_REV), kR11fG11fB10fWord,
+                             "R11F_G11F_B10F round trip");
+        }
+
+        // KHR-GL43.copy_image.functional rgb9_e5 -> r11f_g11f_b10f, all nine target combinations of
+        // which failed on both GPUs. glCopyImageSubData is a raw block move, so the destination
+        // physically holds the source's word - but the readback decoded it to float and re-encoded,
+        // and the destination's blue field is a NaN whose payload float32 does not carry. Every
+        // texel came back 0xf87c0000 (payload 1) instead of 0xf8fc0000 (payload 3): the same
+        // "colour", two bits apart.
+        TEST_F(PackedWordReadbackScenario, ACopiedRgb9E5WordSurvivesInAnR11fG11fB10fDestination) {
+            if (!Ready()) GTEST_SKIP();
+
+            m_src = MakePackedTexture(GL_RGB9_E5, GL_UNSIGNED_INT_5_9_9_9_REV, kRgb9E5Word);
+            m_dst = MakePackedTexture(GL_R11F_G11F_B10F, GL_UNSIGNED_INT_10F_11F_11F_REV, 0u);
+            ASSERT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR)) << "texture setup";
+
+            const GLenum copyError = CopyWholeImage(m_src, GL_TEXTURE_2D, m_dst, GL_TEXTURE_2D);
+            if (copyError != static_cast<GLenum>(GL_NO_ERROR)) {
+                GTEST_SKIP() << "this driver declined the RGB9_E5 -> R11F_G11F_B10F copy (" << copyError << ")";
+            }
+
+            ExpectEveryTexel(ReadPackedWords(m_dst, GL_UNSIGNED_INT_10F_11F_11F_REV), kRgb9E5Word,
+                             "copied word in the R11F_G11F_B10F destination");
+            // ...and the source is still the source. This is verify()'s FIRST check in the
+            // conformance case, and the half that a canonicalizing readback fails on its own.
+            ExpectEveryTexel(ReadPackedWords(m_src, GL_UNSIGNED_INT_5_9_9_9_REV), kRgb9E5Word,
+                             "the RGB9_E5 source after the copy");
+        }
+
+        // KHR-GL43.copy_image.functional *->rgb9_e5 with a GL_RENDERBUFFER source: exactly the three
+        // renderbuffer combinations of each such family failed, and no texture one did. The
+        // destination's CPU shadow is what the readback answered from, the mirror that replays a
+        // copy into it declines when an endpoint is a renderbuffer (there is no shadow to mirror
+        // FROM), and the decline is silent - so glGetTexImage handed back the destination's
+        // pre-copy contents. The word chosen here makes that unmissable: it decodes to the same
+        // all-zero channels the canonical encoder would write as 0x00000000.
+        TEST_F(PackedWordReadbackScenario, ACopyThroughARenderbufferReachesAnRgb9E5Destination) {
+            if (!Ready()) GTEST_SKIP();
+
+            m_src = MakePackedTexture(GL_R11F_G11F_B10F, GL_UNSIGNED_INT_10F_11F_11F_REV, kR11fG11fB10fWord);
+            m_dst = MakePackedTexture(GL_RGB9_E5, GL_UNSIGNED_INT_5_9_9_9_REV, 0xFFFFFFFFu);
+            glGenRenderbuffers(1, &m_rbo);
+            glBindRenderbuffer(GL_RENDERBUFFER, m_rbo);
+            glRenderbufferStorage(GL_RENDERBUFFER, GL_R11F_G11F_B10F, kExtent, kExtent);
+            glBindRenderbuffer(GL_RENDERBUFFER, 0);
+            ASSERT_EQ(glGetError(), static_cast<GLenum>(GL_NO_ERROR)) << "renderbuffer setup";
+
+            // The conformance case's own shape: texture -> renderbuffer -> texture.
+            const GLenum toRenderbuffer = CopyWholeImage(m_src, GL_TEXTURE_2D, m_rbo, GL_RENDERBUFFER);
+            if (toRenderbuffer != static_cast<GLenum>(GL_NO_ERROR)) {
+                GTEST_SKIP() << "this driver declined a renderbuffer copy destination (" << toRenderbuffer << ")";
+            }
+            const GLenum fromRenderbuffer = CopyWholeImage(m_rbo, GL_RENDERBUFFER, m_dst, GL_TEXTURE_2D);
+            if (fromRenderbuffer != static_cast<GLenum>(GL_NO_ERROR)) {
+                GTEST_SKIP() << "this driver declined a renderbuffer copy source (" << fromRenderbuffer << ")";
+            }
+
+            ExpectEveryTexel(ReadPackedWords(m_dst, GL_UNSIGNED_INT_5_9_9_9_REV), kR11fG11fB10fWord,
+                             "copied word in the RGB9_E5 destination");
+        }
+
+    } // namespace
+} // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/SnormAttachmentScenario.cpp

@@ -0,0 +1,245 @@
+// MobileGL - MobileGL/MG_IntegrationTest/Scenarios/SnormAttachmentScenario.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// Scenario - SIGNED-NORMALIZED COLOUR ATTACHMENTS, on a live driver.
+//
+// The bug: a GLES driver without GL_EXT_render_snorm treats every signed-normalized format as
+// texture-only. DirectGLES had a colour-renderable substitute for exactly one of the eight
+// (GL_RGB16_SNORM, through the three-channel widening), so an R8_SNORM or R16_SNORM attachment got
+// no storage the driver would render into: the ES framebuffer was incomplete, the draw landed
+// nowhere, and glGetTexImage fell through to the CPU shadow - all zeroes for a texture created with
+// no data. KHR-GL4x.texture_swizzle renders into a SINGLE-CHANNEL SNORM output for every one of its
+// SNORM source formats, which is why all 46 of its GL43 SNORM cases failed on Mali.
+//
+// THE OTHER HALF, and the reason this scenario asserts VALUES rather than only completeness: the
+// substitute has to be exact. A half float's 11-bit mantissa cannot represent a 16-bit SNORM
+// channel - 23451/32767 quantizes about six SNORM steps away, against a conformance window of one -
+// so the 16-bit formats must land on a 32-bit float even though the 8-bit ones are fine in a half.
+// Trading 46 visible failures for silent precision loss in Iris' SNORM normal buffers would be the
+// worse outcome, so the round trip below is pinned tightly enough to fail on a half-float substitute
+// (tolerance two SNORM steps, half-float error six).
+//
+// WHAT THIS GATE CAN AND CANNOT SEE. Both CI drivers (Mesa llvmpipe) and Adreno expose
+// GL_EXT_render_snorm, so they take the NATIVE path here and the substitution stays dead. That is
+// precisely why the assertions are written as invariants of the format rather than of the fallback:
+// "a signed-normalized colour attachment is complete and round-trips its channel values" has to
+// hold whichever path answers it, so the scenario fails if anyone ever routes these formats to a
+// lossy storage on a driver where it IS live. The substitution itself can only be observed on a
+// device without EXT_render_snorm (Mali Immortalis-G925).
+//
+// DirectGLES only, like the three-channel scenario next door: DirectVulkan resolves SNORM formats
+// on its own terms and asserting Espryt's answers there would pin a coincidence.
+
+#include <string>
+#include <vector>
+
+#include "../Harness/HeadlessGL.h"
+#include "../Harness/ScenarioFixture.h"
+
+#ifdef GLAPI
+#undef GLAPI
+#endif
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glcorearb.h>
+#undef GL_GLEXT_PROTOTYPES
+
+namespace MGITest {
+    namespace {
+
+        constexpr const char* kVS = R"(#version 330 core
+in vec2 aPos;
+void main() {
+    gl_Position = vec4(aPos, 0.0, 1.0);
+}
+)";
+
+        // A uniform rather than a literal so nothing can constant-fold the value into a different
+        // precision than the one the attachment stores.
+        constexpr const char* kFS = R"(#version 330 core
+out vec4 oColor;
+uniform float uValue;
+void main() { oColor = vec4(uValue, 0.0, 0.0, 1.0); }
+)";
+
+        constexpr int kSize = 8;
+
+        // The two channel values the round trip is pinned on. Both are positive on purpose:
+        // glReadPixels applies GL_CLAMP_READ_COLOR (GL_FIXED_ONLY by default) to a fixed-point
+        // colour buffer, so the negative half of a SNORM attachment reads back as 0 and would
+        // measure the clamp instead of the storage.
+        constexpr int kSnorm8Value = 99;
+        constexpr int kSnorm16Value = 23451;
+
+        class SnormAttachmentScenario : public ScenarioTest {
+        protected:
+            void SetUp() override {
+                ScenarioTest::SetUp();
+                if (!Ready()) return;
+                if (Gl().BackendName() != "DirectGLES") {
+                    GTEST_SKIP() << "the signed-normalized substitution is a DirectGLES fallback; backend is "
+                                 << Gl().BackendName();
+                }
+            }
+
+            // A single-level 2D texture in `internalFormat`, or 0 when the driver rejects the
+            // storage outright (which is a different failure from rejecting the ATTACHMENT).
+            static GLuint MakeTexture(GLenum internalFormat) {
+                GLuint texture = 0;
+                glGenTextures(1, &texture);
+                glBindTexture(GL_TEXTURE_2D, texture);
+                glTexStorage2D(GL_TEXTURE_2D, 1, internalFormat, kSize, kSize);
+                if (glGetError() != GL_NO_ERROR) {
+                    glDeleteTextures(1, &texture);
+                    return 0;
+                }
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+                glBindTexture(GL_TEXTURE_2D, 0);
+                return texture;
+            }
+
+            static GLenum SingleAttachmentStatus(GLenum internalFormat) {
+                const GLuint texture = MakeTexture(internalFormat);
+                if (texture == 0) return GL_NONE;
+                GLuint fbo = 0;
+                glGenFramebuffers(1, &fbo);
+                glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo);
+                glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
+                const GLenum status = glCheckFramebufferStatus(GL_DRAW_FRAMEBUFFER);
+                glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
+                glDeleteFramebuffers(1, &fbo);
+                glDeleteTextures(1, &texture);
+                return status;
+            }
+
+            // Renders `value` into the red channel of a fresh `internalFormat` attachment and hands
+            // back what glReadPixels sees. Returns false when the framebuffer never came up, which
+            // is the failure mode this scenario exists for - a draw into an incomplete framebuffer
+            // is dropped by the driver and leaves the caller reading the cleared texture.
+            bool RenderAndReadRed(GLenum internalFormat, float value, float* outRed) {
+                std::string error;
+                const GLuint program = CompileProgram(kVS, kFS, &error);
+                EXPECT_NE(program, 0u) << error;
+                if (program == 0) return false;
+                const GLint valueLocation = glGetUniformLocation(program, "uValue");
+                EXPECT_GE(valueLocation, 0);
+
+                const GLuint texture = MakeTexture(internalFormat);
+                EXPECT_NE(texture, 0u) << "the driver refused the texture storage itself";
+                if (texture == 0) {
+                    glDeleteProgram(program);
+                    return false;
+                }
+
+                GLuint fbo = 0;
+                glGenFramebuffers(1, &fbo);
+                glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+                glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
+                const bool complete = glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE;
+
+                if (complete) {
+                    const float quad[] = {-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f};
+                    GLuint vao = 0;
+                    GLuint vbo = 0;
+                    glGenVertexArrays(1, &vao);
+                    glBindVertexArray(vao);
+                    glGenBuffers(1, &vbo);
+                    glBindBuffer(GL_ARRAY_BUFFER, vbo);
+                    glBufferData(GL_ARRAY_BUFFER, sizeof(quad), quad, GL_STATIC_DRAW);
+                    glEnableVertexAttribArray(0);
+                    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), nullptr);
+                    glUseProgram(program);
+                    glUniform1f(valueLocation, value);
+                    glViewport(0, 0, kSize, kSize);
+                    // Cleared to zero so a dropped draw cannot be mistaken for a correct one.
+                    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
+                    glClear(GL_COLOR_BUFFER_BIT);
+                    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+                    std::vector<float> pixels(static_cast<std::size_t>(kSize) * kSize * 4, -1.0f);
+                    glReadBuffer(GL_COLOR_ATTACHMENT0);
+                    glReadPixels(0, 0, kSize, kSize, GL_RGBA, GL_FLOAT, pixels.data());
+                    if (outRed) *outRed = pixels[0];
+
+                    glDeleteBuffers(1, &vbo);
+                    glDeleteVertexArrays(1, &vao);
+                }
+
+                glBindFramebuffer(GL_FRAMEBUFFER, 0);
+                glDeleteFramebuffers(1, &fbo);
+                glDeleteTextures(1, &texture);
+                glDeleteProgram(program);
+                return complete;
+            }
+        };
+
+        // THE regression gate for the frontend's answer. Every one of these used to be
+        // GL_FRAMEBUFFER_UNSUPPORTED on a driver without EXT_render_snorm, and nothing in the CTS
+        // (or in Iris) checks the status before drawing, so the failure was silent all the way to a
+        // readback of zeroes.
+        TEST_F(SnormAttachmentScenario, SignedNormalizedColorAttachmentsReportComplete) {
+            if (!Ready() || IsSkipped()) return;
+
+            // GL_R8 is the control: colour-renderable in ES core, so it must pass with or without
+            // any substitution. If it ever fails, nothing below means anything.
+            EXPECT_EQ(SingleAttachmentStatus(GL_R8), static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE))
+                << "GL_R8 is ES-core colour-renderable";
+
+            // The single-channel pair KHR-GL4x.texture_swizzle renders into for every SNORM source
+            // format - the whole 46-case failure.
+            EXPECT_EQ(SingleAttachmentStatus(GL_R8_SNORM), static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE));
+            EXPECT_EQ(SingleAttachmentStatus(GL_R16_SNORM), static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE));
+            // ...and the two- and four-channel siblings, which are what a shaderpack actually
+            // declares (Iris colortex buffers in RGBA16_SNORM).
+            EXPECT_EQ(SingleAttachmentStatus(GL_RG8_SNORM), static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE));
+            EXPECT_EQ(SingleAttachmentStatus(GL_RG16_SNORM), static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE));
+            EXPECT_EQ(SingleAttachmentStatus(GL_RGBA8_SNORM), static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE));
+            EXPECT_EQ(SingleAttachmentStatus(GL_RGBA16_SNORM), static_cast<GLenum>(GL_FRAMEBUFFER_COMPLETE));
+
+            EXPECT_EQ(FirstGLError(), 0u) << GLErrorName(FirstGLError());
+        }
+
+        // The other half: whatever storage answers for the attachment has to hold the channel value
+        // to the format's own precision. This is the assertion that fails if the 16-bit formats are
+        // ever routed to a half float - the substitute an implementer naturally reaches for, because
+        // it is what the 8-bit ones correctly use.
+        TEST_F(SnormAttachmentScenario, SignedNormalizedAttachmentsRoundTripTheirChannelValues) {
+            if (!Ready() || IsSkipped()) return;
+
+            const float snorm8Expected = static_cast<float>(kSnorm8Value) / 127.0f;
+            float red8 = -1.0f;
+            ASSERT_TRUE(RenderAndReadRed(GL_R8_SNORM, snorm8Expected, &red8))
+                << "an R8_SNORM colour attachment must be complete before any value can be asserted";
+            // Two 8-bit SNORM steps. A half float is exact here (worst case 0.03 of a step), so this
+            // only has to catch a storage that quantizes harder than the format itself.
+            EXPECT_NEAR(red8, snorm8Expected, 2.0f / 127.0f)
+                << "R8_SNORM attachment lost its channel value";
+            EXPECT_GT(red8, 0.5f) << "the draw never landed - this is the cleared texture, not the rendered one";
+
+            const float snorm16Expected = static_cast<float>(kSnorm16Value) / 32767.0f;
+            float red16 = -1.0f;
+            ASSERT_TRUE(RenderAndReadRed(GL_R16_SNORM, snorm16Expected, &red16))
+                << "an R16_SNORM colour attachment must be complete before any value can be asserted";
+            // Two 16-bit SNORM steps (6.1e-5). A half float would land 1.9e-4 away - three times
+            // this window - which is exactly the failure this bound exists to catch.
+            EXPECT_NEAR(red16, snorm16Expected, 2.0f / 32767.0f)
+                << "R16_SNORM attachment was stored in something that cannot hold 16 signed bits";
+            EXPECT_GT(red16, 0.5f) << "the draw never landed - this is the cleared texture, not the rendered one";
+
+            float red16x4 = -1.0f;
+            ASSERT_TRUE(RenderAndReadRed(GL_RGBA16_SNORM, snorm16Expected, &red16x4))
+                << "an RGBA16_SNORM colour attachment must be complete before any value can be asserted";
+            EXPECT_NEAR(red16x4, snorm16Expected, 2.0f / 32767.0f)
+                << "RGBA16_SNORM attachment was stored in something that cannot hold 16 signed bits";
+
+            EXPECT_EQ(FirstGLError(), 0u) << GLErrorName(FirstGLError());
+        }
+
+    } // namespace
+} // namespace MGITest

MobileGL/MG_IntegrationTest/Scenarios/XfbPrimitiveQueryScenario.cpp

@@ -0,0 +1,268 @@
+// MobileGL - MobileGL/MG_IntegrationTest/Scenarios/XfbPrimitiveQueryScenario.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// What the two transform feedback queries report for a VERTEX-ONLY capture that
+// OVERFLOWS its buffer - the shape of KHR-GL30.transform_feedback.query_vertex_*,
+// and the one place where the two targets must disagree:
+//
+//   * GL_PRIMITIVES_GENERATED counts what the capture stage assembled: 4 points.
+//   * GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN counts what the capture buffers
+//     took. With room for three vertices, a full buffer stops recording whole
+//     primitives (GL 4.6 core 13.2.2), so the answer is 3, not 4 and not 6.
+//
+// Both numbers came from the backend's own GPU counter until the driver underneath
+// DirectGLES was caught reporting exactly twice the written count for this shape
+// (Adreno 830, vertex-only capture issued right after a large render pass). The
+// frontend already computes the desktop-exact number for a capture with no geometry
+// stage, so that is what answers PRIMITIVES_WRITTEN there now - and this scenario is
+// what pins the value, on every backend, without a device.
+//
+// The non-overflowing case is the negative control: with room for all four points
+// the two targets must AGREE at 4, so a "written" that silently reports the
+// generated count cannot pass both cases at once.
+
+#include <cmath>
+#include <string>
+#include <vector>
+
+#include "../Harness/HeadlessGL.h"
+#include "../Harness/ScenarioFixture.h"
+
+#ifdef GLAPI
+#undef GLAPI
+#endif
+#define GL_GLEXT_PROTOTYPES
+#include <GL/gl.h>
+#include <GL/glcorearb.h>
+#undef GL_GLEXT_PROTOTYPES
+
+namespace MGITest {
+    namespace {
+
+        constexpr float kPoison = -1234.0f;
+        // One vec4 per captured point.
+        constexpr std::size_t kFloatsPerVertex = 4;
+        constexpr std::size_t kBytesPerVertex = kFloatsPerVertex * sizeof(float);
+        // The draw: four points, whichever way the capture buffer is sized.
+        constexpr GLsizei kDrawnPoints = 4;
+
+        GLuint CompileShader(GLenum type, const std::string& source, std::string* log) {
+            const GLuint shader = glCreateShader(type);
+            const char* text = source.c_str();
+            glShaderSource(shader, 1, &text, nullptr);
+            glCompileShader(shader);
+            GLint status = GL_FALSE;
+            glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
+            if (status == GL_FALSE) {
+                GLint length = 0;
+                glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
+                std::vector<char> buffer(static_cast<std::size_t>(length) + 1, '\0');
+                glGetShaderInfoLog(shader, length + 1, nullptr, buffer.data());
+                if (log != nullptr) *log = buffer.data();
+                glDeleteShader(shader);
+                return 0;
+            }
+            return shader;
+        }
+
+        // Vertex-only capture program - no geometry stage, so nothing amplifies and the
+        // primitives written are the primitives drawn (up to the buffer's capacity).
+        GLuint BuildCaptureProgram(std::string* log) {
+            const std::string vertexSource = R"(#version 430 core
+layout(location = 0) in vec4 vs_in_value;
+out vec4 vs_out_value;
+void main() {
+  vs_out_value = vs_in_value;
+}
+)";
+            const GLuint vertexShader = CompileShader(GL_VERTEX_SHADER, vertexSource, log);
+            if (vertexShader == 0) return 0;
+            const GLuint program = glCreateProgram();
+            glAttachShader(program, vertexShader);
+            const char* varying = "vs_out_value";
+            glTransformFeedbackVaryings(program, 1, &varying, GL_INTERLEAVED_ATTRIBS);
+            glLinkProgram(program);
+            glDeleteShader(vertexShader);
+            GLint status = GL_FALSE;
+            glGetProgramiv(program, GL_LINK_STATUS, &status);
+            if (status == GL_FALSE) {
+                GLint length = 0;
+                glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
+                std::vector<char> buffer(static_cast<std::size_t>(length) + 1, '\0');
+                glGetProgramInfoLog(program, length + 1, nullptr, buffer.data());
+                if (log != nullptr) *log = buffer.data();
+                glDeleteProgram(program);
+                return 0;
+            }
+            return program;
+        }
+
+        class XfbPrimitiveQueryScenario : public ScenarioTest {
+        protected:
+            void SetUp() override {
+                ScenarioTest::SetUp();
+                if (!Ready()) return;
+
+                std::string log;
+                m_program = BuildCaptureProgram(&log);
+                ASSERT_NE(m_program, 0u) << "capture program failed to build: " << log;
+
+                glGenVertexArrays(1, &m_vao);
+                glBindVertexArray(m_vao);
+                glGenBuffers(1, &m_vbo);
+                glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
+                // Vertex i is (i, i+1, i+2, i+3), so a record that landed in the wrong slot
+                // is as visible as one that never landed at all.
+                float vertices[kDrawnPoints * kFloatsPerVertex] = {};
+                for (int point = 0; point < kDrawnPoints; ++point) {
+                    for (std::size_t component = 0; component < kFloatsPerVertex; ++component) {
+                        vertices[static_cast<std::size_t>(point) * kFloatsPerVertex + component] =
+                            static_cast<float>(point) + static_cast<float>(component);
+                    }
+                }
+                glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+                glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, nullptr);
+                glEnableVertexAttribArray(0);
+                glBindBuffer(GL_ARRAY_BUFFER, 0);
+
+                glGenQueries(2, m_queries);
+                ASSERT_NE(m_queries[0], 0u);
+                ASSERT_NE(m_queries[1], 0u);
+            }
+
+            void TearDown() override {
+                if (!Ready()) return;
+                glDeleteQueries(2, m_queries);
+                glBindVertexArray(0);
+                if (m_vbo != 0) glDeleteBuffers(1, &m_vbo);
+                if (m_vao != 0) glDeleteVertexArrays(1, &m_vao);
+                if (m_program != 0) glDeleteProgram(m_program);
+                glUseProgram(0);
+                ScenarioTest::TearDown();
+            }
+
+            // A capture buffer with room for exactly `vertexCapacity` records, poisoned so
+            // that "captured nothing" is legible, bound to capture point 0.
+            GLuint MakeCaptureBuffer(std::size_t vertexCapacity) {
+                GLuint buffer = 0;
+                glGenBuffers(1, &buffer);
+                glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, buffer);
+                const std::vector<float> poison(vertexCapacity * kFloatsPerVertex, kPoison);
+                glBufferData(GL_TRANSFORM_FEEDBACK_BUFFER,
+                             static_cast<GLsizeiptr>(vertexCapacity * kBytesPerVertex), poison.data(),
+                             GL_DYNAMIC_DRAW);
+                return buffer;
+            }
+
+            // ONE capture span, four points, with both query targets open across it - the
+            // order KHR-GL30.transform_feedback.query_vertex_interleaved_test uses: the
+            // queries wrap the whole span, never the other way round.
+            void RunQueriedSpan(GLuint* written, GLuint* generated) {
+                glEnable(GL_RASTERIZER_DISCARD);
+                glUseProgram(m_program);
+                glBindVertexArray(m_vao);
+
+                glBeginQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, m_queries[0]);
+                glBeginQuery(GL_PRIMITIVES_GENERATED, m_queries[1]);
+                glBeginTransformFeedback(GL_POINTS);
+                glDrawArrays(GL_POINTS, 0, kDrawnPoints);
+                glEndTransformFeedback();
+                glEndQuery(GL_PRIMITIVES_GENERATED);
+                glEndQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN);
+
+                glDisable(GL_RASTERIZER_DISCARD);
+                glUseProgram(0);
+
+                *written = 0xFFFFFFFFu;
+                *generated = 0xFFFFFFFFu;
+                glGetQueryObjectuiv(m_queries[0], GL_QUERY_RESULT, written);
+                glGetQueryObjectuiv(m_queries[1], GL_QUERY_RESULT, generated);
+            }
+
+            // The capture record at slot `point` must be the vertex the draw fetched there.
+            static ::testing::AssertionResult CapturedVertexIs(const float* record, int point) {
+                for (std::size_t component = 0; component < kFloatsPerVertex; ++component) {
+                    const float expected = static_cast<float>(point) + static_cast<float>(component);
+                    const float got = record[component];
+                    // isfinite first: every ordered comparison against a NaN is false, so a
+                    // pair of one-sided range tests REPORTS SUCCESS for uninitialised storage
+                    // that happens to read as NaN.
+                    if (!std::isfinite(got) || std::fabs(got - expected) > 0.01f) {
+                        return ::testing::AssertionFailure()
+                               << "point " << point << " component " << component << " is " << got << ", expected "
+                               << expected << (got == kPoison ? " (the capture never reached these bytes)" : "");
+                    }
+                }
+                return ::testing::AssertionSuccess();
+            }
+
+            GLuint m_program = 0;
+            GLuint m_vao = 0;
+            GLuint m_vbo = 0;
+            GLuint m_queries[2] = {0, 0};
+        };
+
+        // The negative control: the buffer holds every point the draw produces, so both
+        // targets must report the same 4. A "written" that is really the generated count
+        // passes this case and fails the next one; a "written" that is really zero fails
+        // this one.
+        TEST_F(XfbPrimitiveQueryScenario, ACaptureThatFitsReportsEveryPrimitiveOnBothTargets) {
+            if (!Ready()) GTEST_SKIP();
+
+            const GLuint captureBuffer = MakeCaptureBuffer(kDrawnPoints);
+            GLuint written = 0;
+            GLuint generated = 0;
+            RunQueriedSpan(&written, &generated);
+
+            EXPECT_EQ(written, 4u);
+            EXPECT_EQ(generated, 4u);
+
+            std::vector<float> readback(kDrawnPoints * kFloatsPerVertex, kPoison);
+            glGetBufferSubData(GL_TRANSFORM_FEEDBACK_BUFFER, 0,
+                               static_cast<GLsizeiptr>(kDrawnPoints * kBytesPerVertex), readback.data());
+            for (int point = 0; point < kDrawnPoints; ++point) {
+                EXPECT_TRUE(CapturedVertexIs(readback.data() + static_cast<std::size_t>(point) * kFloatsPerVertex,
+                                             point));
+            }
+
+            glDeleteBuffers(1, &captureBuffer);
+            EXPECT_EQ(glGetError(), GL_NO_ERROR);
+        }
+
+        // The pin: four points into a buffer sized for three. The fourth is not written, so
+        // the two targets part ways at 3 and 4 - the exact pair
+        // KHR-GL30.transform_feedback.query_vertex_interleaved_test checks, and the pair the
+        // Adreno driver counter got wrong (it answered 6).
+        TEST_F(XfbPrimitiveQueryScenario, AnOverflowingVertexOnlyCaptureStopsWritingAtTheBufferCapacity) {
+            if (!Ready()) GTEST_SKIP();
+
+            constexpr std::size_t kCapacityVertices = 3;
+            const GLuint captureBuffer = MakeCaptureBuffer(kCapacityVertices);
+            GLuint written = 0;
+            GLuint generated = 0;
+            RunQueriedSpan(&written, &generated);
+
+            EXPECT_EQ(written, 3u) << "the capture buffer holds " << kCapacityVertices << " points";
+            EXPECT_EQ(generated, 4u) << "every point the draw assembled is generated, capacity or not";
+
+            // The three records that DID fit are the first three points, in order: an
+            // overflow truncates the capture, it does not scramble or drop what preceded it.
+            std::vector<float> readback(kCapacityVertices * kFloatsPerVertex, kPoison);
+            glGetBufferSubData(GL_TRANSFORM_FEEDBACK_BUFFER, 0,
+                               static_cast<GLsizeiptr>(kCapacityVertices * kBytesPerVertex), readback.data());
+            for (int point = 0; point < static_cast<int>(kCapacityVertices); ++point) {
+                EXPECT_TRUE(CapturedVertexIs(readback.data() + static_cast<std::size_t>(point) * kFloatsPerVertex,
+                                             point));
+            }
+
+            glDeleteBuffers(1, &captureBuffer);
+            EXPECT_EQ(glGetError(), GL_NO_ERROR);
+        }
+
+    } // namespace
+} // namespace MGITest

MobileGL/MG_State/GLState/BufferState/BufferObject.cpp

@@ -163,7 +163,7 @@ namespace MobileGL::MG_State::GLState {
             if (!m_resource.IsGpuResident() &&
                 !(m_mappingAccess & BufferMappingAccessBit::FlushExplicit)) { // if we didn't flush explicitly
                 if (!(m_mappingAccess & BufferMappingAccessBit::Persistent)) {
-                    Memcpy(m_resource.Bytes() + m_mappedRange.start, m_stagingData.data(),
+                    Memcpy(m_resource.Bytes() + m_mappedRange.start, m_stagingData.data() + m_stagingBias,
                            m_mappedRange.end - m_mappedRange.start);
                 }
                 NotifyFlushMappedRange(m_mappedRange, m_mappingAccess);
@@ -175,6 +175,7 @@ namespace MobileGL::MG_State::GLState {
         m_isMapped = false;
         m_mappingAccess = BufferMappingAccessBit::Null;
         m_mappedRange = {0, 0};
+        m_stagingBias = 0;
         m_ownsStagingData = false;
     }
 
@@ -193,7 +194,7 @@ namespace MobileGL::MG_State::GLState {
         // FLUSH_EXPLICIT maps are never GPU-resident (only coherent maps are adopted), so
         // the staged bytes must be copied into the shadow before the backend reads them.
         if (!(m_mappingAccess & BufferMappingAccessBit::Persistent)) {
-            Memcpy(m_resource.Bytes() + start, m_stagingData.data() + offset, length);
+            Memcpy(m_resource.Bytes() + start, m_stagingData.data() + m_stagingBias + offset, length);
         }
         NotifyFlushMappedRange({start, end}, m_mappingAccess);
     }
@@ -311,6 +312,9 @@ namespace MobileGL::MG_State::GLState {
             m_mappedRange = {0, m_size};
 
             if (m_mappingAccess & BufferMappingAccessBit::Write) {
+                // glMapBuffer maps from offset 0, so no bias: the allocation's own
+                // GL_MIN_MAP_BUFFER_ALIGNMENT-aligned base is what the application must get.
+                m_stagingBias = 0;
                 m_stagingData.resize(m_size);
                 m_ownsStagingData = true;
 
@@ -372,14 +376,21 @@ namespace MobileGL::MG_State::GLState {
         }
 
         if (access & BufferMappingAccessBit::Write) {
-            m_stagingData.resize(range.end - range.start);
+            // ARB_map_buffer_alignment constrains (returned pointer - offset), not the pointer:
+            // a map at offset 63 must hand back a pointer 63 bytes past the alignment grid, which
+            // is exactly what the read path below gets for free from shadowBase + offset. The
+            // staging store has to be biased by the same phase to match, so it over-allocates by
+            // it and the mapped bytes start at data() + m_stagingBias.
+            m_stagingBias = range.start % MIN_MAP_BUFFER_ALIGNMENT;
+            const SizeT mappedLength = range.end - range.start;
+            m_stagingData.resize(m_stagingBias + mappedLength);
             m_ownsStagingData = true;
 
             if (!(access & (BufferMappingAccessBit::InvalidateRange | BufferMappingAccessBit::InvalidateBuffer))) {
-                Memcpy(m_stagingData.data(), m_resource.Bytes() + range.start, m_stagingData.size());
+                Memcpy(m_stagingData.data() + m_stagingBias, m_resource.Bytes() + range.start, mappedLength);
             }
 
-            return m_stagingData.data();
+            return m_stagingData.data() + m_stagingBias;
         } else {
             m_ownsStagingData = false;
             return m_resource.Bytes() + range.start;
@@ -438,7 +449,7 @@ namespace MobileGL::MG_State::GLState {
             return const_cast<Uint8*>(m_resource.Bytes()) + m_mappedRange.start;
         }
         if (m_ownsStagingData) {
-            return const_cast<Uint8*>(m_stagingData.data());
+            return const_cast<Uint8*>(m_stagingData.data()) + m_stagingBias;
         }
         return const_cast<Uint8*>(m_resource.Bytes()) + m_mappedRange.start;
     }

MobileGL/MG_State/GLState/BufferState/BufferObject.h

@@ -239,7 +239,14 @@ namespace MobileGL {
             // Set by MarkGpuWritten, cleared by SyncGpuWrites once the shadow is refreshed.
             Bool m_gpuWritePending = false;
             Range1D m_mappedRange;
-            Vector<Uint8> m_stagingData;
+            // The write-map staging store. MapAlignedData because the application is handed a
+            // pointer into it, and biased by m_stagingBias because ARB_map_buffer_alignment
+            // requires (returned pointer - offset) to be aligned, not the pointer itself: a range
+            // map at offset 63 must hand back a pointer sitting 63 bytes past the alignment grid.
+            // The bias is the offset's phase, so the mapped bytes still start at
+            // m_stagingData.data() + m_stagingBias and the allocation is that much longer.
+            MapAlignedData m_stagingData;
+            SizeT m_stagingBias = 0;
             Bool m_ownsStagingData;
         };
     } // namespace MG_State::GLState

MobileGL/MG_State/GLState/BufferState/PipeResource.h

@@ -10,8 +10,56 @@
 #include <Includes.h>
 #include <MG_Util/Types.h>
 #include <bit>
+#include <new>
+#include <vector>
 
 namespace MobileGL::MG_State::GLState {
+    // GL_MIN_MAP_BUFFER_ALIGNMENT. GL 4.2 / ARB_map_buffer_alignment fix the minimum at 64 and
+    // MobileGL advertises exactly that (MG_Impl/GLImpl/Getter/GL_Getter.cpp reads this constant),
+    // so under-reporting is not available - the implementation has to be brought up to the number
+    // instead. The promise is about POINTERS, not just the query: glMapBuffer must return a
+    // 64-byte-aligned pointer, and glMapBufferRange must return one whose base - the returned
+    // pointer minus the offset the caller asked for - is. Every pointer the frontend hands out
+    // comes from the shadow below or from BufferObject's staging buffer, and std::vector only
+    // promises alignof(std::max_align_t) (16 on aarch64), so both allocations carry the alignment
+    // themselves. One constant for the getter and the allocator, because the two may never
+    // disagree - the same reason the atomic-counter limits are shared through
+    // MG_Util/ShaderTranspiler/Types.h.
+    inline constexpr SizeT MIN_MAP_BUFFER_ALIGNMENT = 64;
+
+    // Allocator that gives every allocation MIN_MAP_BUFFER_ALIGNMENT. Deliberately minimal: the
+    // vectors it backs hold raw bytes and are only ever sized, so allocate/deallocate plus the
+    // rebinding and equality boilerplate std::vector requires is the whole interface.
+    template <typename T>
+    struct MapAlignedAllocator {
+        using value_type = T;
+
+        MapAlignedAllocator() noexcept = default;
+        template <typename U>
+        MapAlignedAllocator(const MapAlignedAllocator<U>&) noexcept {}
+
+        T* allocate(SizeT count) {
+            if (count == 0) return nullptr;
+            return static_cast<T*>(
+                ::operator new(count * sizeof(T), std::align_val_t{MIN_MAP_BUFFER_ALIGNMENT}));
+        }
+        void deallocate(T* pointer, SizeT) noexcept {
+            ::operator delete(pointer, std::align_val_t{MIN_MAP_BUFFER_ALIGNMENT});
+        }
+
+        template <typename U>
+        Bool operator==(const MapAlignedAllocator<U>&) const noexcept {
+            return true;
+        }
+        template <typename U>
+        Bool operator!=(const MapAlignedAllocator<U>&) const noexcept {
+            return false;
+        }
+    };
+
+    // Byte store for anything the application may end up holding a mapped pointer into.
+    using MapAlignedData = std::vector<Uint8, MapAlignedAllocator<Uint8>>;
+
     // Opaque, refcounted handle to the backend's GPU storage for one buffer
     // (the driver-side resource). The active backend derives from it and attaches
     // its own payload (VkBufferResource / GLESBufferResource). Held by PipeResource.
@@ -57,8 +105,8 @@ namespace MobileGL::MG_State::GLState {
         }
         // Direct shadow access, used only by the backend's upload-from-shadow path,
         // which never runs for a GPU-resident (persistent) buffer.
-        Data& Shadow() { return *m_shadow; }
-        const Data& Shadow() const { return *m_shadow; }
+        MapAlignedData& Shadow() { return *m_shadow; }
+        const MapAlignedData& Shadow() const { return *m_shadow; }
 
         // Transition to persistent GPU residency: adopt the backend's coherent
         // mapped base as the source of truth and drop the CPU shadow. The caller
@@ -85,7 +133,10 @@ namespace MobileGL::MG_State::GLState {
         SharedPtr<BackendBufferResource> ReleaseBackend() { return std::move(m_backend); }
 
     private:
-        SharedPtr<Data> m_shadow = MakeShared<Data>();
+        // MapAlignedData, not Data: a read-only glMapBuffer hands the application this very
+        // pointer, and a range map hands it base + offset, so the base has to be on the
+        // GL_MIN_MAP_BUFFER_ALIGNMENT grid for either to satisfy ARB_map_buffer_alignment.
+        SharedPtr<MapAlignedData> m_shadow = MakeShared<MapAlignedData>();
         void* m_gpuMapped = nullptr;
         SharedPtr<BackendBufferResource> m_backend;
     };

MobileGL/MG_State/GLState/Core.h

@@ -328,6 +328,7 @@ namespace MobileGL {
                 // transform feedback counter cannot see them - nothing was being captured.
                 void AddTransformFeedbackPausedPrimitives(Uint64 primitives) {
                     m_transformFeedbackPausedPrimitiveCounter += primitives;
+                    m_transformFeedbackGeneratedPrimitiveCounter += primitives;
                 }
                 Uint64 GetTransformFeedbackPausedPrimitiveCounter() const {
                     return m_transformFeedbackPausedPrimitiveCounter;
@@ -342,8 +343,55 @@ namespace MobileGL {
                 // (pre-clamp; drives the GS strip capture-order fixup at EndTF).
                 void AddTransformFeedbackInputPrimitives(Uint64 primitives) {
                     m_transformFeedbackInputPrimitives += primitives;
+                    m_transformFeedbackGeneratedPrimitiveCounter += primitives;
                 }
                 Uint64 GetTransformFeedbackInputPrimitives() const { return m_transformFeedbackInputPrimitives; }
+                // What a GL_PRIMITIVES_GENERATED query counts over its span: every primitive the
+                // capture stage assembled, including the ones a paused span discarded (those are
+                // generated but never written). Kept as its own running total rather than derived
+                // from the input counter above, which BeginTransformFeedback resets per span while
+                // a query may cover several of them.
+                Uint64 GetTransformFeedbackGeneratedCounter() const {
+                    return m_transformFeedbackGeneratedPrimitiveCounter;
+                }
+                // Capture draws whose written-primitive count the CPU accounting reproduced
+                // exactly, and the subset it could not: a program with a geometry stage amplifies
+                // by whatever the shader emits, which only the driver's own counter knows. The
+                // transform feedback queries diff both over their span to decide whether the CPU
+                // delta may stand in for the backend's GPU result (GL_Query.cpp).
+                void AddTransformFeedbackAccountedCaptureDraw() { ++m_transformFeedbackAccountedCaptureDraws; }
+                Uint64 GetTransformFeedbackAccountedCaptureDraws() const {
+                    return m_transformFeedbackAccountedCaptureDraws;
+                }
+                void AddTransformFeedbackGeometryCaptureDraw() { ++m_transformFeedbackGeometryCaptureDraws; }
+                Uint64 GetTransformFeedbackGeometryCaptureDraws() const {
+                    return m_transformFeedbackGeometryCaptureDraws;
+                }
+
+                // Conditional rendering (GL 4.6 core 10.9). `discard` is the verdict already
+                // resolved from the query object at glBeginConditionalRender - the predicate is
+                // read ONCE there, not per command, because GL specifies the block against the
+                // result available at Begin and re-reading it would let a query that is still
+                // being written change the answer mid-block.
+                void BeginConditionalRender(GLuint queryId, GLenum mode, Bool discard) {
+                    m_conditionalRenderActive = true;
+                    m_conditionalRenderQuery = queryId;
+                    m_conditionalRenderMode = mode;
+                    m_conditionalRenderDiscards = discard;
+                }
+                void EndConditionalRender() {
+                    m_conditionalRenderActive = false;
+                    m_conditionalRenderQuery = 0;
+                    m_conditionalRenderMode = GL_NONE;
+                    m_conditionalRenderDiscards = false;
+                }
+                Bool IsConditionalRenderActive() const { return m_conditionalRenderActive; }
+                GLuint GetConditionalRenderQuery() const { return m_conditionalRenderQuery; }
+                // Whether the commands GL 4.6 core 10.9 makes conditional are being discarded
+                // right now. False whenever no block is open, so a caller needs no second test.
+                Bool ConditionalRenderDiscardsCommands() const {
+                    return m_conditionalRenderActive && m_conditionalRenderDiscards;
+                }
 
                 // Transform feedback objects (ARB_transform_feedback2 / GL 4.0 core).
                 // The capture state above and the indexed GL_TRANSFORM_FEEDBACK_BUFFER
@@ -439,6 +487,16 @@ namespace MobileGL {
                 Uint64 m_transformFeedbackPausedPrimitiveCounter = 0;
                 Uint64 m_transformFeedbackCapturedVertices = 0;
                 Uint64 m_transformFeedbackInputPrimitives = 0;
+                Uint64 m_transformFeedbackGeneratedPrimitiveCounter = 0;
+                Uint64 m_transformFeedbackAccountedCaptureDraws = 0;
+                Uint64 m_transformFeedbackGeometryCaptureDraws = 0;
+
+                // Conditional rendering. Context state, not object state: GL 4.6 core 10.9 allows
+                // exactly one block open at a time and no object owns it.
+                Bool m_conditionalRenderActive = false;
+                Bool m_conditionalRenderDiscards = false;
+                GLuint m_conditionalRenderQuery = 0;
+                GLenum m_conditionalRenderMode = GL_NONE;
 
                 // Everything a transform feedback object owns while it is NOT the bound one.
                 struct TransformFeedbackObjectState {

MobileGL/MG_State/GLState/ProgramState/ProgramLinkTask.cpp

@@ -8,6 +8,8 @@
 
 #include "ProgramLinkTask.h"
 
+#include <MG_State/GLState/ProgramState/ProgramTranslationCache.h>
+
 #include <MG_State/GLState/VertexArrayState/VertexArrayObject.h>
 #include <MG_Util/Async/ShaderCompilePool.h>
 #include <MG_Util/Converters/GLToStr/GLEnumConverter.h>
@@ -36,6 +38,70 @@ namespace {
         return std::min(backendLimit, capacity);
     }
 
+    // Everything the post-link query surface ever asks a glslang::TType, flattened into a
+    // POD. The list is closed and was audited call site by call site: nothing after the link
+    // walks a struct, a type name or the AST, so there is no recursion to mirror.
+    //
+    // Why it has to be flattened at all: TObjectReflection::type points into the TProgram's
+    // OWN TPoolAllocator (reflection.cpp clones each TType into it), so every one of these
+    // pointers dangles the moment the TProgram is released - and releasing it is exactly what
+    // lets a link be served from the L1 translation memo without a parse.
+    static MobileGL::MG_State::GLState::ProgramObject::TypeFacts MakeTypeFacts(const glslang::TType* type) {
+        MobileGL::MG_State::GLState::ProgramObject::TypeFacts facts;
+        if (type == nullptr) return facts;
+        facts.isArray = type->isArray();
+        facts.isSizedArray = type->isSizedArray();
+        facts.isMatrix = type->isMatrix();
+        facts.isVector = type->isVector();
+        facts.isOpaque = type->isOpaque();
+        facts.isTexture = type->isTexture();
+        facts.isImage = type->isImage();
+        facts.isDouble = type->getBasicType() == glslang::EbtDouble;
+        facts.isVoid = type->getBasicType() == glslang::EbtVoid;
+        facts.basicType = static_cast<MobileGL::Int>(type->getBasicType());
+        // Stored RAW, exactly as glslang reports them (0 for a non-matrix, 1 for a scalar),
+        // because the callers already gate on isMatrix()/isVector() themselves.
+        facts.vectorSize = type->getVectorSize();
+        facts.matrixCols = type->getMatrixCols();
+        facts.matrixRows = type->getMatrixRows();
+        const glslang::TQualifier& qualifier = type->getQualifier();
+        facts.isBuffer = qualifier.storage == glslang::EvqBuffer;
+        facts.isPatch = qualifier.patch;
+        facts.hasIndex = qualifier.hasIndex();
+        facts.layoutIndex = static_cast<MobileGL::Int>(qualifier.layoutIndex);
+        facts.hasFormat = qualifier.hasFormat();
+        facts.layoutFormat = static_cast<MobileGL::Uint>(qualifier.getFormat());
+        facts.layoutMatrix = static_cast<MobileGL::Int>(qualifier.layoutMatrix);
+        return facts;
+    }
+
+    // One glslang::TObjectReflection, flattened. Shared by uniforms, blocks, pipe inputs and
+    // pipe outputs, because glslang reflects all four as TObjectReflection.
+    static MobileGL::MG_State::GLState::ProgramObject::ResourceReflection MakeResourceReflection(
+        const glslang::TObjectReflection& object) {
+        MobileGL::MG_State::GLState::ProgramObject::ResourceReflection record;
+        record.name = object.name;
+        record.glDefineType = object.glDefineType;
+        record.offset = object.offset;
+        record.size = object.size;
+        record.index = object.index;
+        record.counterIndex = object.counterIndex;
+        record.arrayStride = object.arrayStride;
+        record.topLevelArraySize = object.topLevelArraySize;
+        record.topLevelArrayStride = object.topLevelArrayStride;
+        record.binding = object.getBinding();
+        record.location = object.layoutLocation();
+        record.stages = static_cast<MobileGL::Uint32>(object.stages);
+        record.type = MakeTypeFacts(object.getType());
+        // GL_UNIFORM_SIZE / GL_ARRAY_SIZE, resolved here so no caller needs the TType:
+        // TObjectReflection::size carries the element count only for a NON-block array, so
+        // the sized-array outer count wins whenever it exists.
+        const glslang::TType* type = object.getType();
+        record.arraySize = (type != nullptr && type->isSizedArray()) ? type->getOuterArraySize()
+                                                                     : (object.size < 1 ? 1 : object.size);
+        return record;
+    }
+
     static MobileGL::String StripArrayElementSuffix(const MobileGL::String& name) {
         const MobileGL::SizeT bracket = name.find('[');
         return bracket == MobileGL::String::npos ? name : name.substr(0, bracket);
@@ -63,6 +129,180 @@ namespace {
         return element;
     }
 
+    // GL 4.6 core 7.7 / ARB_shader_atomic_counters: within one binding no two atomic counters
+    // may occupy the same bytes, every offset is a multiple of 4, and no counter may reach past
+    // GL_MAX_ATOMIC_COUNTER_BUFFER_SIZE. glslang enforces all three in fixOffset(), which the
+    // Vulkan-relaxed parse never reaches - vkRelaxedRemapUniformVariable folds the atomic_uint
+    // into a synthesized storage block and returns from declareVariable() before fixOffset()
+    // runs, clearing explicitOffset on the way ("xxTODO: use logic from fixOffset()"). Two
+    // counters declared at the same binding AND the same offset therefore linked cleanly.
+    //
+    // The offsets themselves survive that lowering (reflection and the SPIR-V generator both
+    // honour layoutOffset), so the check belongs here, over the same model the GL queries answer
+    // from. Returns the info-log line for an illegal layout, empty for a legal one.
+    static MobileGL::String ValidateAtomicCounterLayout(glslang::TProgram& reflection) {
+        using MobileGL::Bool;
+        using MobileGL::Int;
+        using MobileGL::SizeT;
+        using MobileGL::String;
+        using MobileGL::Vector;
+        namespace Transpiler = MobileGL::MG_Util::ShaderTranspiler;
+
+        const Int blockCount = reflection.getNumUniformBlocks();
+        if (blockCount <= 0) return {};
+        const SizeT prefixLength = std::strlen(Transpiler::ATOMIC_COUNTER_BLOCK_PREFIX);
+        Vector<Bool> isCounterBlock(static_cast<SizeT>(blockCount), false);
+        Bool anyCounterBlock = false;
+        for (Int i = 0; i < blockCount; ++i) {
+            const auto& block = reflection.getUniformBlock(i);
+            isCounterBlock[static_cast<SizeT>(i)] =
+                block.name.compare(0, prefixLength, Transpiler::ATOMIC_COUNTER_BLOCK_PREFIX) == 0;
+            anyCounterBlock = anyCounterBlock || isCounterBlock[static_cast<SizeT>(i)];
+        }
+        if (!anyCounterBlock) return {}; // every program that declares no atomic counter
+
+        struct CounterSpan {
+            Int offset = 0;
+            Int size = 0;
+            String name;
+        };
+        Vector<Vector<CounterSpan>> spansByBlock(static_cast<SizeT>(blockCount));
+        const Int uniformCount = reflection.getNumUniformVariables();
+        for (Int i = 0; i < uniformCount; ++i) {
+            const auto& uniform = reflection.getUniform(i);
+            const Int owner = uniform.index;
+            if (owner < 0 || owner >= blockCount || !isCounterBlock[static_cast<SizeT>(owner)]) continue;
+            const Int offset = uniform.offset;
+            if (offset < 0) continue; // no offset recorded; nothing to compare
+            Int elements = uniform.size > 1 ? uniform.size : 1;
+            if (const glslang::TType* type = uniform.getType(); type != nullptr && type->isArray()) {
+                elements = type->isSizedArray() ? type->getCumulativeArraySize() : 1;
+            }
+            const Int size = elements * static_cast<Int>(sizeof(MobileGL::Uint32));
+            if (offset % 4 != 0) {
+                return std::format("Atomic counter '{}' is declared at offset {}, which is not a multiple of 4.",
+                                   uniform.name, offset);
+            }
+            if (offset > Transpiler::MAX_ATOMIC_COUNTER_BUFFER_SIZE - size) {
+                return std::format("Atomic counter '{}' ends at byte {}, past the {}-byte "
+                                   "GL_MAX_ATOMIC_COUNTER_BUFFER_SIZE.",
+                                   uniform.name, offset + size, Transpiler::MAX_ATOMIC_COUNTER_BUFFER_SIZE);
+            }
+            auto& spans = spansByBlock[static_cast<SizeT>(owner)];
+            for (const CounterSpan& existing : spans) {
+                if (offset < existing.offset + existing.size && existing.offset < offset + size) {
+                    return std::format("Atomic counters '{}' and '{}' share a binding and overlap at byte offset {}.",
+                                       existing.name, uniform.name, std::max(offset, existing.offset));
+                }
+            }
+            spans.push_back({offset, size, uniform.name});
+        }
+        return {};
+    }
+
+    // GL 4.6 core 7.6: LinkProgram FAILS when a stage's count of active image uniforms exceeds
+    // GL_MAX_{VERTEX,TESS_CONTROL,TESS_EVALUATION,GEOMETRY,FRAGMENT,COMPUTE}_IMAGE_UNIFORMS, or
+    // when their sum exceeds GL_MAX_COMBINED_IMAGE_UNIFORMS. Nothing enforced it: glslang carries
+    // those numbers in TBuiltInResource only so gl_Max*ImageUniforms can expand from them, and
+    // its linker never counts uniforms against them - so a program declaring one image uniform
+    // more than the limit linked cleanly and then rendered nothing.
+    //
+    // The limits are the ones glGetIntegerv answers (MG_Impl/GLImpl/Getter/GL_Getter.cpp), the
+    // hardcoded tessellation zeros included: a program may not exceed a limit the implementation
+    // advertises, whatever the driver underneath would have taken.
+    //
+    // Counts the APPLICATION's image uniforms. The DirectGLES read/write split emits a second
+    // declaration for an image a stage both reads and writes (MG_Backend/DirectGLES/Utils.h), but
+    // that happens in the backend after this link, and counting the expanded set here would
+    // reject programs that are legal by the numbers GL advertises. Returns the info-log line for
+    // a program over a limit, empty for one within them.
+    static MobileGL::String ValidateImageUniformLimits(
+        glslang::TProgram& reflection, const MobileGL::MG_Util::ShaderTranspiler::CompileEnv& env) {
+        using MobileGL::Array;
+        using MobileGL::Int;
+        using MobileGL::SizeT;
+        using MobileGL::UnorderedMap;
+
+        static constexpr EShLanguage kStages[] = {EShLangVertex,   EShLangTessControl, EShLangTessEvaluation,
+                                                  EShLangGeometry, EShLangFragment,    EShLangCompute};
+        static constexpr const char* kLimitNames[] = {
+            "GL_MAX_VERTEX_IMAGE_UNIFORMS",   "GL_MAX_TESS_CONTROL_IMAGE_UNIFORMS",
+            "GL_MAX_TESS_EVALUATION_IMAGE_UNIFORMS", "GL_MAX_GEOMETRY_IMAGE_UNIFORMS",
+            "GL_MAX_FRAGMENT_IMAGE_UNIFORMS", "GL_MAX_COMPUTE_IMAGE_UNIFORMS"};
+        constexpr SizeT kStageCount = sizeof(kStages) / sizeof(kStages[0]);
+        const Int limits[kStageCount] = {env.params.MaxVertexImageUniforms,
+                                         0,
+                                         0,
+                                         env.params.MaxGeometryImageUniforms,
+                                         env.params.MaxFragmentImageUniforms,
+                                         env.params.MaxComputeImageUniforms};
+
+        // Reflection spells an image ARRAY one of two ways, and which one it picks depends on how
+        // the shader indexed it: a variable index makes glslang expand the array into one entry
+        // per element ("u_image[0]".."u_image[8]", each carrying the ELEMENT type), while an
+        // array never dereferenced at all stays a single entry carrying the array type. One
+        // program can even produce both spellings for the same array. So neither counting entries
+        // nor trusting the declared size is right on its own - they are reconciled per declared
+        // name with a max, which is exact for either spelling and cannot double-count the mixture.
+        struct ImageUse {
+            Int entries = 0;  // reflection entries seen for this name in this stage
+            Int declared = 0; // largest element count any of them declared
+        };
+        UnorderedMap<MobileGL::String, Array<ImageUse, kStageCount>> useByName;
+
+        const Int uniformCount = reflection.getNumUniformVariables();
+        for (Int i = 0; i < uniformCount; ++i) {
+            const auto& uniform = reflection.getUniform(i);
+            const glslang::TType* type = uniform.getType();
+            if (type == nullptr || !type->isImage()) continue;
+            // An array occupies one image unit per element; an unsized one (never indexed, so
+            // never more than the single element glslang kept) counts as one.
+            Int elements = uniform.size > 1 ? uniform.size : 1;
+            if (type->isArray()) {
+                elements = type->isSizedArray() ? type->getCumulativeArraySize() : 1;
+            }
+            // `stages` is the set of stages that REFERENCE the uniform, which is exactly what GL
+            // counts: an image declared in two stages costs a unit in each, and one no stage
+            // reads is not active at all and costs nothing.
+            Array<ImageUse, kStageCount>* use = nullptr;
+            for (SizeT stage = 0; stage < kStageCount; ++stage) {
+                if ((static_cast<unsigned>(uniform.stages) & (1u << static_cast<unsigned>(kStages[stage]))) == 0) {
+                    continue;
+                }
+                // The one insert this uniform performs, so the reference survives the rest of the
+                // stage loop - a flat hash map relocates on insert, never on read.
+                if (use == nullptr) {
+                    use = &useByName[StripArrayElementSuffix(uniform.name)];
+                }
+                ++(*use)[stage].entries;
+                (*use)[stage].declared = std::max((*use)[stage].declared, elements);
+            }
+        }
+
+        Int counts[kStageCount] = {};
+        for (const auto& entry : useByName) {
+            for (SizeT stage = 0; stage < kStageCount; ++stage) {
+                counts[stage] += std::max(entry.second[stage].entries, entry.second[stage].declared);
+            }
+        }
+
+        Int combined = 0;
+        for (SizeT stage = 0; stage < kStageCount; ++stage) {
+            combined += counts[stage];
+            if (counts[stage] > limits[stage]) {
+                return std::format("This program uses {} active image uniforms in one stage, more than the {} "
+                                   "{} allows.",
+                                   counts[stage], limits[stage], kLimitNames[stage]);
+            }
+        }
+        if (combined > env.params.MaxCombinedImageUniforms) {
+            return std::format("This program uses {} active image uniforms across its stages, more than the {} "
+                               "GL_MAX_COMBINED_IMAGE_UNIFORMS allows.",
+                               combined, env.params.MaxCombinedImageUniforms);
+        }
+        return {};
+    }
+
     static bool IsBuiltInPipelineOutput(const glslang::TObjectReflection& output) {
         const auto* type = output.getType();
         return type && type->getQualifier().builtIn != glslang::EbvNone;
@@ -309,6 +549,20 @@ namespace MobileGL::MG_State::GLState {
 
         MGLOG_D("ProgramObject %u: Link body start, shaders to link: %zu", in.externalIndex, in.shaders.size());
 
+        if (!ValidateAttachedShaders()) return;
+
+        // The two merges below read the COMPILE snapshots only - no parsed shader - so they
+        // run before the L1 probe, which needs the merged opaque bindings in its key.
+        MergeShaderSideChannels();
+        if (!artifacts.infoLog.empty()) return; // a conflicting explicit uniform location
+
+        // ---- L1 of the shader translation memo ----
+        // Everything below this point - the parse, the link, mapIO, GlslangToSpv, spirv-opt,
+        // buildReflection and the global-UBO routing - is what a hit skips. See
+        // ProgramTranslationCache.h.
+        spirvHandoff.spirvCacheKey = BuildSpirvCacheKey(env);
+        if (TryPublishFromTranslationCache()) return;
+
         Vector<SharedPtr<glslang::TShader>> shaders;
         if (!ConsumeShaders(shaders)) return;
 
@@ -335,30 +589,6 @@ namespace MobileGL::MG_State::GLState {
             }
         }
 
-        // Merge the shaders' lexically extracted explicit uniform locations. The same
-        // uniform declared in several stages must agree on its location (config-A glslang
-        // enforced this at mapIO; the relaxed parse no longer sees the qualifiers).
-        for (const auto& shader : in.shaders) {
-            const ShaderCompileArtifacts& compiled = CompiledArtifacts(shader.compiled);
-            for (const auto& [name, location] : compiled.explicitUniformLocations) {
-                const auto [it, inserted] = artifacts.linkedExplicitUniformLocations.emplace(name, location);
-                if (!inserted && it->second != location) {
-                    artifacts.infoLog = std::format(
-                        "Uniform '{}' is declared with conflicting explicit locations ({} and {}) "
-                        "across stages.",
-                        name, it->second, location);
-                    DeferLog(std::format("ProgramObject {}: Link failed - {}", in.externalIndex, artifacts.infoLog));
-                    return;
-                }
-            }
-            // Sampler/image layout(binding = N) initial units, likewise invisible to the
-            // relaxed parse. Stage order matches the old per-stage mapIO capture, so a
-            // name declared in several stages keeps the last stage's binding as before.
-            for (const auto& [name, binding] : compiled.explicitOpaqueBindings) {
-                artifacts.explicitOpaqueUniformBindings[name] = binding;
-            }
-        }
-
         ProgramAttrib attrib{.shaders = Move(shaders),
                              .explicitVertexInLocations = in.explicitAttribLocations,
                              .explicitFragmentOutLocations = in.explicitFragDataLocation,
@@ -497,14 +727,138 @@ namespace MobileGL::MG_State::GLState {
         spirvHandoff.reflection.uniformIndexInTProgram = artifacts.uniformIndexInTProgram;
         spirvHandoff.reflection.tProgramUniformIndexToGl = artifacts.tProgramUniformIndexToGl;
         spirvHandoff.reflection.maxUniformLocation = artifacts.maxUniformLocation;
+        // The owned reflection mirror, and the block index space its global-UBO test needs.
+        // BuildGlobalUboRouting reads BOTH - per-uniform array size, opaqueness, GL type and
+        // matrix shape, plus "is this a member of a GL-visible block". Leaving them out of the
+        // handoff is not a compile error, it is a SILENT one: every array collapses to a
+        // single element and every element past the first falls through to the fallback tail
+        // allocator (ProgramTest.NestedStructArrayUniformElementWrites catches exactly that).
+        spirvHandoff.reflection.uniformReflection = artifacts.uniformReflection;
+        spirvHandoff.reflection.blockReflection = artifacts.blockReflection;
+        spirvHandoff.reflection.tProgramBlockIndexToGl = artifacts.tProgramBlockIndexToGl;
+        // Phase B pairs this with its own SpirvArtifacts to insert the completed front end.
+        // A COPY, because the GL-thread join moves `artifacts` out of this node before phase B
+        // runs - and with the TProgram dropped, because a memo must never hold a glslang arena.
+        if (spirvHandoff.spirvCacheKey.Valid()) {
+            auto forCache = MakeShared<ProgramObject::LinkArtifacts>(artifacts);
+            forCache->program.reset();
+            spirvHandoff.linkArtifactsForCache = Move(forCache);
+        }
         spirvHandoff.ready = true;
         MGLOG_D("ProgramObject %u: phase A done, %zu module(s) handed to the SPIR-V job", in.externalIndex,
                 spirvHandoff.shaderTypes.size());
     }
 
-    Bool ProgramLinkTask::ConsumeShaders(Vector<SharedPtr<glslang::TShader>>& outShaders) {
-        outShaders.assign(in.shaders.size(), nullptr);
+    // The L1 key. Every input below is one that can change the SPIR-V this program
+    // generates; see the key inventory on SpirvTranslationKeyInputs.
+    //
+    // Deliberately NOT keyed on: nothing that only steers a BACKEND transpile - see the
+    // classification on CompileEnv::frontendFingerprint, and L2's own key in
+    // MG_Util/ShaderTranspiler/TranslationCache.h.
+    MG_Util::ShaderTranspiler::TranslationCacheKey ProgramLinkTask::BuildSpirvCacheKey(
+        const MG_Util::ShaderTranspiler::CompileEnv& env) const {
+        using namespace MG_Util::ShaderTranspiler;
+        if (!ShaderTranslationCacheEnabled()) return {};
 
+        SpirvTranslationKeyInputs keyInputs;
+        // The FRONT-END fingerprint, not env.fingerprint: L1 must be shared by two contexts
+        // on different GPUs whenever glslang would produce the same thing for them. See the
+        // classification on CompileEnv::frontendFingerprint.
+        keyInputs.frontendFingerprint = env.frontendFingerprint;
+        // Always 0 on both production parse paths (ShaderCompileTask::RunCompilePipeline and
+        // ClaimParsedShader's re-parse). In the key regardless, so that a future non-zero
+        // value cannot alias a module parsed without it.
+        keyInputs.shaderCompileFlags = 0;
+        keyInputs.enableSpirvValidation = in.enableSpirvValidation;
+        keyInputs.stages.reserve(in.shaders.size());
+        for (const LinkShaderInput& shader : in.shaders) {
+            const ShaderCompileArtifacts& compiled = CompiledArtifacts(shader.compiled);
+            if (compiled.preprocessedSource.empty()) {
+                // No text to key on - an internal shader object, or an artifact this build
+                // did not populate. Refuse to key rather than key on nothing.
+                return {};
+            }
+            keyInputs.stages.push_back(SpirvTranslationKeyInputs::Stage{
+                .type = MG_Util::ConvertShaderStageToGLEnum(shader.stage),
+                .preprocessedSource = StringView(compiled.preprocessedSource)});
+        }
+        if (keyInputs.stages.empty()) return {};
+        keyInputs.explicitVertexInLocations = &in.explicitAttribLocations;
+        keyInputs.explicitFragmentOutLocations = &in.explicitFragDataLocation;
+        keyInputs.explicitFragmentOutIndices = &in.explicitFragDataIndex;
+        keyInputs.explicitOpaqueUniformBindings = &artifacts.explicitOpaqueUniformBindings;
+        // In the key ONLY because the payload now carries the reflection: transform feedback
+        // is resolved by reading the linked intermediates and never perturbs the generated
+        // SPIR-V, but it does shape xfbVaryings / xfbStrides / xfbBufferMode /
+        // gsStripTriangles, and maxFragmentOutputColorNumber decides whether the link is
+        // rejected at all. Widening a payload means widening the key.
+        keyInputs.requestedXfbVaryings = &in.requestedXfbVaryings;
+        keyInputs.xfbBufferMode = static_cast<Uint32>(in.requestedXfbBufferMode);
+        keyInputs.maxFragmentOutputColorNumber = in.maxFragmentOutputColorNumber;
+        return BuildSpirvTranslationKey(keyInputs);
+    }
+
+    // The link rejections that need nothing but the compile snapshots. They run before the
+    // L1 memo is consulted, so a hit can never paper over a program that must fail to link.
+    // The two lexical side channels the relaxed parse cannot provide, merged across stages:
+    // explicit default-block uniform locations (which must agree, or the link fails) and
+    // sampler/image layout(binding = N) initial units. Reads the COMPILE snapshots only, so
+    // it is legal - and necessary - before any shader is parsed: the merged bindings are part
+    // of the L1 memo key.
+    void ProgramLinkTask::MergeShaderSideChannels() {
+        // Merge the shaders' lexically extracted explicit uniform locations. The same
+        // uniform declared in several stages must agree on its location (config-A glslang
+        // enforced this at mapIO; the relaxed parse no longer sees the qualifiers).
+        for (const auto& shader : in.shaders) {
+            const ShaderCompileArtifacts& compiled = CompiledArtifacts(shader.compiled);
+            for (const auto& [name, location] : compiled.explicitUniformLocations) {
+                const auto [it, inserted] = artifacts.linkedExplicitUniformLocations.emplace(name, location);
+                if (!inserted && it->second != location) {
+                    artifacts.infoLog = std::format(
+                        "Uniform '{}' is declared with conflicting explicit locations ({} and {}) "
+                        "across stages.",
+                        name, it->second, location);
+                    DeferLog(std::format("ProgramObject {}: Link failed - {}", in.externalIndex, artifacts.infoLog));
+                    return;
+                }
+            }
+            // Sampler/image layout(binding = N) initial units, likewise invisible to the
+            // relaxed parse. Stage order matches the old per-stage mapIO capture, so a
+            // name declared in several stages keeps the last stage's binding as before.
+            for (const auto& [name, binding] : compiled.explicitOpaqueBindings) {
+                artifacts.explicitOpaqueUniformBindings[name] = binding;
+            }
+        }
+
+    }
+
+    // An L1 hit: the entire front end, published without constructing a TShader or a
+    // TProgram. Everything here is a copy out of plain owned data - `link.program` is null in
+    // the payload by construction, and nothing reads it any more.
+    Bool ProgramLinkTask::TryPublishFromTranslationCache() {
+        if (!spirvHandoff.spirvCacheKey.Valid()) return false;
+        const ProgramTranslationResultPtr hit =
+            GetProgramTranslationCache().Find(spirvHandoff.spirvCacheKey);
+        if (!hit) return false;
+
+        artifacts = hit->link;
+        spirvHandoff.shaderTypes.resize(in.shaders.size());
+        for (SizeT i = 0; i < in.shaders.size(); i++) {
+            spirvHandoff.shaderTypes[i] = MG_Util::ConvertShaderStageToGLEnum(in.shaders[i].stage);
+        }
+        // An ALIASING SharedPtr: it points at the payload's SpirvArtifacts while sharing
+        // ownership of the whole payload, so phase B publishes them without a second copy and
+        // without any chance of the entry being evicted from under it.
+        spirvHandoff.cachedSpirv =
+            SharedPtr<const ProgramObject::SpirvArtifacts>(hit, &hit->spirv);
+        spirvHandoff.ready = true;
+        MGLOG_D("ProgramObject %u: L1 cache hit - the whole front end was reused; no parse, no "
+                "link, no SPIR-V generation",
+                in.externalIndex);
+        return true;
+    }
+
+    Bool ProgramLinkTask::ValidateAttachedShaders() {
         // GL 4.6 core 7.3: a compute shader may only be linked with other compute shaders -
         // the compute pipeline has no other stages to link against, so a program that mixes
         // them must fail to link (KHR-GL43.compute_shader.api-program).
@@ -526,8 +880,6 @@ namespace MobileGL::MG_State::GLState {
             const LinkShaderInput& input = in.shaders[i];
             const GLenum shaderType = MG_Util::ConvertShaderStageToGLEnum(input.stage);
             const ShaderCompileArtifacts& compiled = CompiledArtifacts(input.compiled);
-            MGLOG_D("ProgramObject %u: Preparing shader[%zu] stage %s", in.externalIndex, i,
-                    MG_Util::ConvertGLEnumToString(shaderType).c_str());
 
             if (!compiled.compileStatus) {
                 // The compile log LEADS the quoted source, and that order is load-bearing:
@@ -546,6 +898,17 @@ namespace MobileGL::MG_State::GLState {
                                      in.externalIndex, i, artifacts.infoLog));
                 return false;
             }
+        }
+        return true;
+    }
+
+    Bool ProgramLinkTask::ConsumeShaders(Vector<SharedPtr<glslang::TShader>>& outShaders) {
+        outShaders.assign(in.shaders.size(), nullptr);
+        for (SizeT i = 0; i < in.shaders.size(); i++) {
+            const LinkShaderInput& input = in.shaders[i];
+            const GLenum shaderType = MG_Util::ConvertShaderStageToGLEnum(input.stage);
+            MGLOG_D("ProgramObject %u: Preparing shader[%zu] stage %s", in.externalIndex, i,
+                    MG_Util::ConvertGLEnumToString(shaderType).c_str());
             String reparseLog;
             outShaders[i] = input.compiled->ClaimParsedShader(reparseLog);
             if (!outShaders[i]) {
@@ -606,6 +969,22 @@ namespace MobileGL::MG_State::GLState {
             return false;
         }
 
+        if (String atomicCounterError = ValidateAtomicCounterLayout(*artifacts.program);
+            !atomicCounterError.empty()) {
+            artifacts.infoLog = Move(atomicCounterError);
+            DeferLog(std::format("ProgramObject {}: Link failed - {}", in.externalIndex, artifacts.infoLog));
+            ProgramObject::ResetLinkArtifacts(artifacts);
+            return false;
+        }
+
+        if (String imageUniformError = ValidateImageUniformLimits(*artifacts.program, env);
+            !imageUniformError.empty()) {
+            artifacts.infoLog = Move(imageUniformError);
+            DeferLog(std::format("ProgramObject {}: Link failed - {}", in.externalIndex, artifacts.infoLog));
+            ProgramObject::ResetLinkArtifacts(artifacts);
+            return false;
+        }
+
         // ---------- GL-facing index spaces (relaxed-parse cleanup) ----------
         // Blocks first: global-UBO membership drives the uniform filter below. The
         // synthesized MGL_GLOBAL_UBO is a transpiler artifact - its members are GL
@@ -658,7 +1037,16 @@ namespace MobileGL::MG_State::GLState {
         //    MGL_GLOBAL_UBO, so reflection cannot provide them ("source-explicit");
         //  - glslang's layoutLocation() for opaque uniforms, where the qualifier
         //    survives the relaxed parse (and mapIO auto-assigns the rest).
-        constexpr Uint kNoLocation = glslang::TQualifier::layoutLocationEnd;
+        //
+        // "no effective location yet". Deliberately OUTSIDE the location space rather than
+        // glslang::TQualifier::layoutLocationEnd, which is the first location past the pool and
+        // therefore only one off a legal one - a sentinel that sits at the boundary it guards has
+        // to be re-proved safe every time the ceiling moves, and glslang uses that same value for
+        // "this opaque uniform has no location" as well.
+        constexpr Uint kNoLocation = ~static_cast<Uint>(0);
+        // The ceiling glGetIntegerv(GL_MAX_UNIFORM_LOCATIONS) advertises, which is what the
+        // allocator below has to honour: locations 0..kMaxUniformLocations-1 and no others.
+        constexpr Uint kMaxUniformLocations = static_cast<Uint>(ProgramObject::MAX_UNIFORM_LOCATIONS);
         Vector<Uint> effectiveLocation(tProgramUniformCount, kNoLocation);
         Vector<Bool> locationIsSourceExplicit(tProgramUniformCount, false);
         UnorderedMap<String, Uint> structExplicitCursor; // declared root -> next member location
@@ -695,13 +1083,19 @@ namespace MobileGL::MG_State::GLState {
                     cursor->second += static_cast<Uint>(GetUniformLocationSpan(uniform));
                 }
             }
-            if (effectiveLocation[i] == kNoLocation && type != nullptr && type->isOpaque()) {
+            // glslang parks "no location" at layoutLocationEnd, which is a real location in this
+            // table's numbering - test for it explicitly rather than letting it through as one.
+            if (effectiveLocation[i] == kNoLocation && type != nullptr && type->isOpaque() &&
+                uniform.layoutLocation() != glslang::TQualifier::layoutLocationEnd) {
                 effectiveLocation[i] = uniform.layoutLocation();
             }
             if (locationIsSourceExplicit[i] &&
-                effectiveLocation[i] + static_cast<Uint>(GetUniformLocationSpan(uniform)) > kNoLocation) {
+                effectiveLocation[i] + static_cast<Uint>(GetUniformLocationSpan(uniform)) > kMaxUniformLocations) {
                 // Config A rejected out-of-range explicit locations at parse; keep them
-                // from growing the location table unboundedly.
+                // from growing the location table unboundedly. Stated against the advertised
+                // GL_MAX_UNIFORM_LOCATIONS, because that is the rule being enforced (GL 4.6 core
+                // 7.6.1): an array whose LAST element passes the ceiling is a link error even
+                // though its base compiled fine.
                 artifacts.infoLog = std::format("Uniform '{}' explicit location {} is out of range.", uniform.name,
                                                 effectiveLocation[i]);
                 ProgramObject::ResetLinkArtifacts(artifacts);
@@ -709,12 +1103,55 @@ namespace MobileGL::MG_State::GLState {
             }
         }
 
-        Int requiredUniformLocations = 0;
+        // ARB_explicit_uniform_location / GL 4.6 core 7.6.1: an explicit location is RESERVED
+        // whether or not the uniform turned out to be active. The dead default-block uniforms
+        // filtered out of glUniformIndexToTProgram above are invisible to every GL query - which
+        // is correct - but their locations must still be kept out of the implicit allocator's
+        // reach, or an implicit uniform is handed a location the source already claimed.
+        //
+        // Deliberately NOT written into artifacts.uniformLocations or uniformIndexInTProgram:
+        // glGetUniformLocation must keep answering -1 for a dead uniform, and a location no
+        // application can legally obtain must not become writable through glUniform*. The
+        // occupancy therefore lives in its own bitset, built once the table has been sized.
+        Vector<Pair<Uint, Int>> deadExplicitReservations;
+        Int deadReservedLocationCount = 0;
+        for (Int i = 0; i < tProgramUniformCount; i++) {
+            if (artifacts.tProgramUniformIndexToGl[i] >= 0) continue; // GL-visible: handled above
+            const auto& uniform = artifacts.program->getUniform(i);
+            if (!isGlobalUboMember(uniform) || uniform.stages != 0) continue;
+            const Int* explicitLocation = findExplicitLocation(uniform.name);
+            if (explicitLocation == nullptr) continue;
+
+            const Uint location = static_cast<Uint>(*explicitLocation);
+            const Int locationSpan = GetUniformLocationSpan(uniform);
+            if (location + static_cast<Uint>(locationSpan) > kMaxUniformLocations) {
+                artifacts.infoLog = std::format("Uniform '{}' explicit location {} is out of range.", uniform.name,
+                                                location);
+                ProgramObject::ResetLinkArtifacts(artifacts);
+                return false;
+            }
+            deadExplicitReservations.emplace_back(location, locationSpan);
+            deadReservedLocationCount += locationSpan;
+            artifacts.maxUniformLocation = std::max(artifacts.maxUniformLocation, location + locationSpan - 1);
+            MGLOG_D("ProgramObject %u: Reflection - inactive uniform '%s' reserves locations %u..%u without "
+                    "becoming GL-visible",
+                    in.externalIndex, uniform.name.c_str(), location, location + locationSpan - 1);
+        }
+
+        Int requiredUniformLocations = deadReservedLocationCount;
+        // The same count restricted to DEFAULT-BLOCK uniforms, which is the only thing
+        // GL_MAX_UNIFORM_LOCATIONS bounds. requiredUniformLocations cannot serve: it also carries
+        // named-block members, which take a slot in this allocator's table (an implementation
+        // detail) but consume no GL uniform location at all, so a big UBO array would otherwise
+        // fail a link the spec allows.
+        Int defaultBlockLocationDemand = deadReservedLocationCount;
         for (const Int i : artifacts.glUniformIndexToTProgram) {
             auto& uniform = artifacts.program->getUniform(i);
             const Uint location = effectiveLocation[i];
             const Int locationSpan = GetUniformLocationSpan(uniform);
             requiredUniformLocations += locationSpan;
+            const Bool inNamedBlock = uniform.index >= 0 && !isGlobalUboMember(uniform);
+            if (!inNamedBlock) defaultBlockLocationDemand += locationSpan;
             if (location != kNoLocation) {
                 artifacts.maxUniformLocation = std::max(artifacts.maxUniformLocation, location + locationSpan - 1);
             }
@@ -727,6 +1164,22 @@ namespace MobileGL::MG_State::GLState {
         MGLOG_D("ProgramObject %u: Reflection - computed maxUniformLocation=%u uniformNameMaxLength=%d",
                 in.externalIndex, artifacts.maxUniformLocation, artifacts.uniformNameMaxLength);
 
+        // GL 4.6 core 7.6.1: explicit, implicit and reserved-but-inactive default-block uniforms
+        // all draw from the one GL_MAX_UNIFORM_LOCATIONS pool, and a program asking for more than
+        // the implementation advertises FAILS TO LINK
+        // (KHR-GL43.explicit_uniform_location.uniform-loc-negative-link-max-num-of-locations).
+        // A single uniform whose own span passes the ceiling was already rejected above; this is
+        // the aggregate half of the same rule.
+        if (defaultBlockLocationDemand > static_cast<Int>(kMaxUniformLocations)) {
+            artifacts.infoLog =
+                std::format("Uniform locations exhausted: the default-block uniforms need {} locations but "
+                            "GL_MAX_UNIFORM_LOCATIONS is {}.",
+                            defaultBlockLocationDemand, kMaxUniformLocations);
+            DeferLog(std::format("ProgramObject {}: Link failed - {}", in.externalIndex, artifacts.infoLog));
+            ProgramObject::ResetLinkArtifacts(artifacts);
+            return false;
+        }
+
         if (artifacts.maxUniformLocation + 1 < requiredUniformLocations) {
             MGLOG_D("ProgramObject %u: Reflection - maxUniformLocation+1 (%u) < requiredUniformLocations (%d), "
                     "adjusting",
@@ -741,6 +1194,27 @@ namespace MobileGL::MG_State::GLState {
                                                 glslang::TQualifier::layoutLocationEnd);
         artifacts.uniformSamplerOrImageUnitIndex.resize(artifacts.maxUniformLocation + 1, -1);
 
+        // Occupancy for the inactive explicit uniforms collected above: a set bit means "the
+        // source claimed this location", which is enough to keep the two implicit passes off it
+        // without making the location reachable through any GL entry point. A location the
+        // fallback grow path mints later is past this bitset by construction (every reservation
+        // was folded into maxUniformLocation before the table was sized), so the lookup treats
+        // out-of-range as free rather than resizing in lockstep.
+        // Left empty - and unallocated - when nothing reserved anything, which is every program in
+        // the shader-pack corpus; the lookup below reads an empty bitset as "nothing is reserved".
+        Vector<Bool> reservedLocation;
+        if (!deadExplicitReservations.empty()) {
+            reservedLocation.assign(artifacts.maxUniformLocation + 1, false);
+            for (const auto& [reservedBase, reservedSpan] : deadExplicitReservations) {
+                for (Int element = 0; element < reservedSpan; ++element) {
+                    reservedLocation[reservedBase + element] = true;
+                }
+            }
+        }
+        const auto locationIsReserved = [&reservedLocation](SizeT location) {
+            return location < reservedLocation.size() && reservedLocation[location];
+        };
+
         Vector<int> unallocatedUniformIndex;
 
         // Pass 1: source-explicit locations. These are API contract
@@ -785,7 +1259,8 @@ namespace MobileGL::MG_State::GLState {
             Bool spanIsFree = location + locationSpan - 1 <= artifacts.maxUniformLocation;
             for (Int element = 0; spanIsFree && element < locationSpan; ++element) {
                 spanIsFree =
-                    artifacts.uniformIndexInTProgram[location + element] == glslang::TQualifier::layoutLocationEnd;
+                    artifacts.uniformIndexInTProgram[location + element] == glslang::TQualifier::layoutLocationEnd &&
+                    !locationIsReserved(location + element);
             }
             if (!spanIsFree) {
                 artifacts.uniformLocations[uniform.name] = kNoLocation;
@@ -817,7 +1292,8 @@ namespace MobileGL::MG_State::GLState {
                 bool hasRoom = locNeedle + locationSpan - 1 <= artifacts.maxUniformLocation;
                 for (Int element = 0; hasRoom && element < locationSpan; ++element) {
                     hasRoom = artifacts.uniformIndexInTProgram[locNeedle + element] ==
-                              glslang::TQualifier::layoutLocationEnd;
+                                  glslang::TQualifier::layoutLocationEnd &&
+                              !locationIsReserved(locNeedle + element);
                 }
                 if (!hasRoom) continue;
                 // Found a vacant location at locNeedle
@@ -987,9 +1463,78 @@ namespace MobileGL::MG_State::GLState {
             MGLOG_D("ProgramObject %u: Reflection - UBO[%d] name='%s' size=%u binding=%d", in.externalIndex, i,
                     ubo.name.c_str(), ubo.size, ubo.getBinding());
         }
+
+        SnapshotGlslangReflection();
         return true;
     }
 
+    // The last thing DoReflection does, and the thing that lets everything after it stop
+    // caring that a glslang::TProgram ever existed: copy every reflection record the GL query
+    // surface reads into LinkArtifacts' own owned tables.
+    //
+    // Indexed by TPROGRAM index throughout - the same space glUniformIndexToTProgram,
+    // tProgramUniformIndexToGl and uniformIndexInTProgram already speak - so the accessors
+    // that used to call program->getUniform(i) index uniformReflection[i] and are otherwise
+    // unchanged.
+    void ProgramLinkTask::SnapshotGlslangReflection() {
+        glslang::TProgram& program = *artifacts.program;
+
+        // Blocks FIRST: a uniform's effective layoutMatrix is resolved against its owning
+        // block below, which needs the block records to already exist.
+        const Int blockCount = program.getNumUniformBlocks();
+        artifacts.blockReflection.clear();
+        artifacts.blockReflection.reserve(static_cast<SizeT>(blockCount));
+        for (Int i = 0; i < blockCount; ++i) {
+            artifacts.blockReflection.push_back(MakeResourceReflection(program.getUniformBlock(i)));
+        }
+
+        const Int uniformCount = program.getNumUniformVariables();
+        artifacts.uniformReflection.clear();
+        artifacts.uniformReflection.reserve(static_cast<SizeT>(uniformCount));
+        artifacts.uniformIndexByName.clear();
+        artifacts.uniformIndexByName.reserve(static_cast<SizeT>(uniformCount));
+        for (Int i = 0; i < uniformCount; ++i) {
+            ProgramObject::UniformReflection record = MakeResourceReflection(program.getUniform(i));
+            // A block-level layout(row_major)/(column_major) that the member did not inherit
+            // in its own qualifier. Resolved once HERE rather than at every GL_UNIFORM_* query,
+            // which is what the getUniformBlock() fallback in the old accessors was doing.
+            if (record.type.layoutMatrix == static_cast<Int>(glslang::ElmNone) && record.index >= 0 &&
+                record.index < static_cast<Int>(artifacts.blockReflection.size())) {
+                record.type.layoutMatrix = artifacts.blockReflection[record.index].type.layoutMatrix;
+            }
+            // Keyed on the REFLECTED name and on uniforms only. That is deliberate and is the
+            // filtered semantics the old code hand-rolled: glslang's TReflection::nameToIndex
+            // also holds block and function entries, which is exactly why every
+            // getUniformIndex() call site re-checked getUniform(idx).name == name afterwards.
+            // First writer wins, so a duplicated name resolves the way a forward scan would.
+            artifacts.uniformIndexByName.emplace(record.name, i);
+            artifacts.uniformReflection.push_back(Move(record));
+        }
+
+        const Int pipeInputCount = program.getNumPipeInputs();
+        artifacts.pipeInputReflection.clear();
+        artifacts.pipeInputReflection.reserve(static_cast<SizeT>(pipeInputCount));
+        for (Int i = 0; i < pipeInputCount; ++i) {
+            artifacts.pipeInputReflection.push_back(MakeResourceReflection(program.getPipeInput(i)));
+        }
+
+        const Int pipeOutputCount = program.getNumPipeOutputs();
+        artifacts.pipeOutputReflection.clear();
+        artifacts.pipeOutputReflection.reserve(static_cast<SizeT>(pipeOutputCount));
+        for (Int i = 0; i < pipeOutputCount; ++i) {
+            artifacts.pipeOutputReflection.push_back(MakeResourceReflection(program.getPipeOutput(i)));
+        }
+
+        artifacts.lastStageIsFragment = program.getIntermediate(EShLangFragment) != nullptr;
+        for (Uint dim = 0; dim < 3u; ++dim) {
+            artifacts.computeLocalSize[dim] = program.getLocalSize(static_cast<Int>(dim));
+        }
+        MGLOG_D("ProgramObject %u: Reflection - snapshot: %zu uniform(s), %zu block(s), %zu input(s), "
+                "%zu output(s)",
+                in.externalIndex, artifacts.uniformReflection.size(), artifacts.blockReflection.size(),
+                artifacts.pipeInputReflection.size(), artifacts.pipeOutputReflection.size());
+    }
+
     Bool ProgramLinkTask::ValidateFragmentOutputLocations() {
         if (!artifacts.program) return false;
         // The pipe-output list is the output interface of the program's LAST stage. Only a

MobileGL/MG_State/GLState/ProgramState/ProgramLinkTask.h

@@ -12,6 +12,7 @@
 #include <MG_State/GLState/ProgramState/ShaderCompileTask.h>
 #include <MG_Util/Async/JobNode.h>
 #include <MG_Util/ShaderTranspiler/CompileEnv.h>
+#include <MG_Util/ShaderTranspiler/TranslationCache.h>
 
 namespace MobileGL::MG_State::GLState {
     // One attached shader, as the link sees it: never the ShaderObject, always a snapshot.
@@ -116,6 +117,27 @@ namespace MobileGL::MG_State::GLState {
             // for phase B after the join has moved `artifacts` away.
             ProgramObject::LinkArtifacts reflection;
 
+            // L1 shader-translation memo key for this program's SPIR-V (see
+            // MG_Util/ShaderTranspiler/TranslationCache.h). Built HERE, at the tail of phase
+            // A, and not by phase B - two reasons, both structural:
+            //   * the key covers the four link-time request maps and the merged opaque
+            //     bindings, and one of those (explicitOpaqueUniformBindings) lives in
+            //     `artifacts`, which phase B is forbidden to read because the GL-thread join
+            //     moves it out from under phase B;
+            //   * built once, it serves both the lookup and the insert, so the program's
+            //     sources are copied into the blob exactly once per link.
+            // Invalid (null blob) when the cache is disabled, or when a stage arrived
+            // without preprocessed source - in which case phase B simply translates.
+            MG_Util::ShaderTranspiler::TranslationCacheKey spirvCacheKey;
+
+            // Set on an L1 HIT: phase B publishes these SpirvArtifacts verbatim instead of
+            // generating anything. Null on a miss.
+            SharedPtr<const ProgramObject::SpirvArtifacts> cachedSpirv;
+            // Set on a MISS: the LinkArtifacts phase B has to pair with its own SpirvArtifacts
+            // to insert the completed front end. Copied here rather than read off the node,
+            // because the GL-thread join MOVES `artifacts` out before phase B runs.
+            SharedPtr<const ProgramObject::LinkArtifacts> linkArtifactsForCache;
+
             // The one flag phase B tests before doing anything: false means this link never
             // reached the tail of RunBody (it failed, or was cancelled mid-body).
             Bool ready = false;
@@ -142,8 +164,31 @@ namespace MobileGL::MG_State::GLState {
         // ---- the link body, split exactly as ProgramObject::Link() had it ----
         // Each returns false to abort the link with `artifacts.infoLog` already set, which is
         // GL's definition of a failed link: LINK_STATUS false plus a log, never a GL error.
+        // The two link-rejection gates that need no parsed shader: a compute stage mixed
+        // with any other, and an attached shader that failed to compile. Split out of
+        // ConsumeShaders so they still run - in the same order, with the same diagnostics -
+        // BEFORE the L1 memo is consulted, rather than behind a hit that would skip them.
+        // The two lexical side channels the relaxed parse cannot provide, merged across
+        // stages. Reads the compile snapshots only, so it runs before any parse - the merged
+        // opaque bindings are part of the L1 memo key. Sets artifacts.infoLog and leaves
+        // linkStatus false when two stages disagree on an explicit uniform location.
+        void MergeShaderSideChannels();
+        Bool ValidateAttachedShaders();
         Bool ConsumeShaders(Vector<SharedPtr<glslang::TShader>>& outShaders);
+        // Publishes a whole front end straight out of the L1 memo: no TShader, no TProgram,
+        // no SPIR-V generation. Returns false on a miss.
+        Bool TryPublishFromTranslationCache();
+
+        // The L1 memo key for the SPIR-V this program is about to generate, or an invalid
+        // key when the cache is off or a stage has no preprocessed source to key on.
+        // Called at the tail of RunBody, where every input it needs is still owned by this
+        // node and `artifacts` has not yet been published.
+        MG_Util::ShaderTranspiler::TranslationCacheKey BuildSpirvCacheKey(
+            const MG_Util::ShaderTranspiler::CompileEnv& env) const;
         Bool DoReflection(const MG_Util::ShaderTranspiler::CompileEnv& env);
+        // Copies every reflection record the GL query surface reads out of the glslang
+        // TProgram into LinkArtifacts own owned tables. Runs at the tail of DoReflection.
+        void SnapshotGlslangReflection();
         Bool ValidateFragmentOutputLocations();
         Bool ResolveTransformFeedbackVaryings();
         void ResolveGsTriangleStripCapture(const glslang::TIntermediate* captureIntermediate);

MobileGL/MG_State/GLState/ProgramState/ProgramObject.cpp

@@ -615,15 +615,22 @@ namespace MobileGL::MG_State::GLState {
 
 
     Int ProgramObject::GetFragmentDataLocation(const char* name) {
-        if (!Artifacts().program || !name) return -1;
+        // Answered from the OWNED pipe-output snapshot, not from Artifacts().program. The live
+        // TProgram is null on a translation-cache L1 hit - that is the entire point of the memo
+        // - and it is also null for any program that never linked. The old `if
+        // (!Artifacts().program) return -1` guard silently produced the never-linked answer for
+        // a perfectly good cached program, so glGetFragDataLocation returned -1 for every
+        // fragment output of it. The empty snapshot gives the never-linked case the same -1
+        // without needing the guard at all.
+        if (!name) return -1;
 
         const auto explicitLocation = Artifacts().linkedFragDataLocation.find(name);
-        const Int outputCount = Artifacts().program->getNumPipeOutputs();
-        for (Int index = 0; index < outputCount; ++index) {
-            const auto& output = Artifacts().program->getPipeOutput(index);
+        for (const PipeOutputReflection& output : Artifacts().pipeOutputReflection) {
             if (output.name != name) continue;
-            if (explicitLocation != Artifacts().linkedFragDataLocation.end()) return static_cast<Int>(explicitLocation->second);
-            return static_cast<Int>(output.layoutLocation());
+            if (explicitLocation != Artifacts().linkedFragDataLocation.end()) {
+                return static_cast<Int>(explicitLocation->second);
+            }
+            return output.location;
         }
         return -1;
     }

MobileGL/MG_State/GLState/ProgramState/ProgramObject.h

@@ -24,6 +24,85 @@ namespace MobileGL::MG_State::GLState {
 
     class ProgramObject {
     public:
+        // GL_MAX_UNIFORM_LOCATIONS: locations 0 .. MAX_UNIFORM_LOCATIONS-1 are the whole legal
+        // range (GL 4.6 core 7.6.1 / ARB_explicit_uniform_location). Shared with GL_Getter rather
+        // than spelled twice, because the link and the query must agree exactly - the CTS declares
+        // a uniform at the advertised value minus one and expects it to link
+        // (KHR-GL43.explicit_uniform_location.uniform-loc-max).
+        //
+        // Tied to glslang's own ceiling and NOT raisable past it: ParseHelper rejects
+        // `layout(location = N)` for N >= TQualifier::layoutLocationEnd at COMPILE time, so
+        // layoutLocationEnd - 1 is the largest location any shader in this stack can declare -
+        // which makes exactly layoutLocationEnd locations, 0 .. layoutLocationEnd - 1, the pool.
+        // Advertising more would promise a location no shader could name. Comfortably above the
+        // 1024 GL 4.3 requires.
+        static constexpr Int MAX_UNIFORM_LOCATIONS = static_cast<Int>(glslang::TQualifier::layoutLocationEnd);
+
+        // Everything the query surface ever asked a glslang::TType, flattened. Twenty
+        // predicates, no recursion: nothing post-link ever walks a struct, a type name or the
+        // AST, so a POD covers the whole surface exactly.
+        struct TypeFacts {
+            Bool isArray = false;
+            // A runtime-sized array (a storage block's unsized trailing member) is an array
+            // that is NOT sized; GL_ARRAY_SIZE reports 0 for it.
+            Bool isSizedArray = false;
+            Bool isMatrix = false;
+            Bool isVector = false;
+            Bool isOpaque = false;
+            Bool isTexture = false;
+            Bool isImage = false;
+            Bool isDouble = false;   // getBasicType() == EbtDouble
+            Bool isVoid = false;     // getBasicType() == EbtVoid (hidden block members)
+            Bool isBuffer = false;   // getQualifier().storage == EvqBuffer
+            Bool isPatch = false;    // getQualifier().patch
+            Bool hasIndex = false;   // getQualifier().hasIndex()
+            Bool hasFormat = false;  // getQualifier().hasFormat()
+            Int vectorSize = 0;
+            Int matrixCols = 0;
+            Int matrixRows = 0;
+            Int layoutIndex = 0;     // getQualifier().layoutIndex
+            Uint layoutFormat = 0;   // getQualifier().getFormat()
+            // glslang::TLayoutMatrix, widened. For a uniform this is already RESOLVED against
+            // the owning block's qualifier, so the getUniformBlock() fallback the old
+            // accessors carried is gone.
+            Int layoutMatrix = 0;
+            // glslang::TBasicType, widened - ApplyUniformInitialValues and the typed
+            // glGetUniform* paths compare against a handful of enumerators.
+            Int basicType = 0;
+        };
+
+        // One glslang::TObjectReflection, flattened. Used for uniforms, blocks, pipe inputs
+        // and pipe outputs alike, because glslang reflects all four as TObjectReflection.
+        struct ResourceReflection {
+            String name;
+            GLenum glDefineType = 0;
+            Int offset = -1;
+            // TObjectReflection::size, RAW. For a uniform prefer `arraySize` below, which is
+            // the resolved GL_UNIFORM_SIZE answer.
+            Int size = 0;
+            // TObjectReflection::index - for a uniform, the TPROGRAM block index owning it
+            // (-1 for a default-block one; translate with GlBlockIndexFromTProgram).
+            Int index = -1;
+            Int counterIndex = -1;
+            Int arrayStride = 0;
+            Int topLevelArraySize = 0;
+            Int topLevelArrayStride = 0;
+            Int binding = -1;
+            Int location = -1; // layoutLocation()
+            // EShLanguageMask of the stages that reference it; 0 means "declared but read by
+            // nobody", which is what the dead-default-block-uniform filter tests.
+            Uint32 stages = 0;
+            // GL_UNIFORM_SIZE / GL_ARRAY_SIZE, already resolved through the
+            // isSizedArray()/getOuterArraySize()/size fallback.
+            GLint arraySize = 1;
+            TypeFacts type;
+        };
+
+        using UniformReflection = ResourceReflection;
+        using BlockReflection = ResourceReflection;
+        using PipeInputReflection = ResourceReflection;
+        using PipeOutputReflection = ResourceReflection;
+
         ProgramObject(Uint externalIndex) : m_externalIndex(externalIndex), m_lifetimeId(AllocateLifetimeId()) {}
         // Cancel-not-join, exactly like ~ShaderObject: the link job owns its inputs, so an
         // in-flight link whose program just went away is safe to abandon where it stands.
@@ -134,8 +213,7 @@ namespace MobileGL::MG_State::GLState {
             const Int index = Artifacts().uniformIndexInTProgram[base];
             // "[k]" only addresses arrays ("scalar[0]" is not a uniform name), and only
             // in-range elements.
-            const glslang::TType* type = Artifacts().program->getUniform(index).getType();
-            if (type == nullptr || !type->isArray()) return -1;
+            if (!UniformAt(index).type.isArray) return -1;
             if (static_cast<GLint>(element) >= GetUniformArraySizeByTIndex(index)) return -1;
             const Int location = base + (Int)element;
             if (!UniformLocationsAliasSameUniform(base, location)) return -1;
@@ -175,44 +253,35 @@ namespace MobileGL::MG_State::GLState {
         }
 
         Int GetActiveUniformIndex(const String& name) const {
-            const Int tProgramCount = static_cast<Int>(Artifacts().tProgramUniformIndexToGl.size());
-            const Int uniformIndex = Artifacts().program->getUniformIndex(name.c_str());
-            if (uniformIndex >= 0 && uniformIndex < tProgramCount &&
-                Artifacts().program->getUniform(uniformIndex).name == name) {
-                return GlUniformIndexFromTProgram(uniformIndex);
+            // uniformIndexByName is keyed by the REFLECTED name, so a lookup that hits is
+            // already the exact-match the old code re-verified with a string compare after
+            // glslang's getUniformIndex(); a lookup that misses needs no bounds check.
+            const auto& byName = Artifacts().uniformIndexByName;
+            if (const auto direct = byName.find(name); direct != byName.end()) {
+                return GlUniformIndexFromTProgram(direct->second);
             }
 
             // Reflection stores an array uniform under "arr[0]"; accept the bare "arr"
             // spelling too. The reverse ("arr[0]" against a bare "arr" entry) is kept for
             // robustness against non-suffixed reflection entries.
             if (!name.empty() && name.back() != ']') {
-                const String suffixedName = name + "[0]";
-                const Int suffixedIndex = Artifacts().program->getUniformIndex(suffixedName.c_str());
-                if (suffixedIndex >= 0 && suffixedIndex < tProgramCount &&
-                    Artifacts().program->getUniform(suffixedIndex).name == suffixedName) {
-                    return GlUniformIndexFromTProgram(suffixedIndex);
-                }
-                return -1;
+                const auto suffixed = byName.find(name + "[0]");
+                return suffixed != byName.end() ? GlUniformIndexFromTProgram(suffixed->second) : -1;
             }
 
             if (name.length() <= 3 || name.compare(name.length() - 3, 3, "[0]") != 0) return -1;
-            const String baseName = name.substr(0, name.length() - 3);
-            const Int baseIndex = Artifacts().program->getUniformIndex(baseName.c_str());
-            if (baseIndex < 0 || baseIndex >= tProgramCount) return -1;
-            return Artifacts().program->getUniform(baseIndex).name == baseName ? GlUniformIndexFromTProgram(baseIndex)
-                                                                     : -1;
+            const auto base = byName.find(name.substr(0, name.length() - 3));
+            return base != byName.end() ? GlUniformIndexFromTProgram(base->second) : -1;
         }
 
         Bool IsValidUniformLocation(Int location) const { return IsValidUniformLocation(Artifacts(), location); }
 
         GLenum GetUniformType(Uint location) const {
-            auto& uniform = Artifacts().program->getUniform(Artifacts().uniformIndexInTProgram[location]);
-            return uniform.glDefineType;
+            return UniformAt(Artifacts().uniformIndexInTProgram[location]).glDefineType;
         }
 
         GLenum GetActiveUniformType(Uint index) const {
-            auto& uniform = Artifacts().program->getUniform(TProgramUniformIndex(index));
-            return uniform.glDefineType;
+            return UniformAt(TProgramUniformIndex(index)).glDefineType;
         }
 
         // Number of active array elements (GL_UNIFORM_SIZE / GL_ARRAY_SIZE); 1 for a non-array.
@@ -229,16 +298,15 @@ namespace MobileGL::MG_State::GLState {
         }
 
         Int GetActiveUniformBlockIndex(Uint index) const {
-            auto& uniform = Artifacts().program->getUniform(TProgramUniformIndex(index));
             // Members of the synthesized global UBO are default-block uniforms to GL: -1.
-            return GlBlockIndexFromTProgram(uniform.index);
+            return GlBlockIndexFromTProgram(UniformAt(TProgramUniformIndex(index)).index);
         }
 
         // GL_UNIFORM_OFFSET: byte offset within the owning named block; -1 for a default-block
         // uniform. The relaxed parse gives global-UBO members real byte offsets, but GL must keep
         // seeing them as default-block uniforms, so gate on the GL-visible block index.
         GLint GetActiveUniformOffset(Uint index) const {
-            const auto& uniform = Artifacts().program->getUniform(TProgramUniformIndex(index));
+            const auto& uniform = UniformAt(TProgramUniformIndex(index));
             if (GlBlockIndexFromTProgram(uniform.index) < 0) return -1;
             return uniform.offset;
         }
@@ -252,13 +320,12 @@ namespace MobileGL::MG_State::GLState {
         // generated SPIR-V lay the array out with std140 16-byte-rounded strides. MobileGL's UBO
         // layout is always std140, where every array element stride rounds up to a vec4.
         GLint GetActiveUniformArrayStride(Uint index) const {
-            const auto& uniform = Artifacts().program->getUniform(TProgramUniformIndex(index));
+            const auto& uniform = UniformAt(TProgramUniformIndex(index));
             if (GlBlockIndexFromTProgram(uniform.index) < 0) return -1;
-            const glslang::TType* type = uniform.getType();
-            if (type == nullptr || !type->isArray()) return 0;
-            if (type->isMatrix()) {
+            if (!uniform.type.isArray) return 0;
+            if (uniform.type.isMatrix) {
                 const bool rowMajor = GetActiveUniformIsRowMajor(index) != 0;
-                const int vectors = rowMajor ? type->getMatrixRows() : type->getMatrixCols();
+                const int vectors = rowMajor ? uniform.type.matrixRows : uniform.type.matrixCols;
                 return GetActiveUniformMatrixStride(index) * vectors;
             }
             return 16; // scalars and vectors: std140 rounds the element stride up to a vec4
@@ -272,15 +339,12 @@ namespace MobileGL::MG_State::GLState {
         // check suffices; the getUniformBlock() fallback is defensive for a config that instead leaves
         // an inheriting member's layoutMatrix == ElmNone.
         GLint GetActiveUniformIsRowMajor(Uint index) const {
-            const auto& uniform = Artifacts().program->getUniform(TProgramUniformIndex(index));
+            const auto& uniform = UniformAt(TProgramUniformIndex(index));
             if (GlBlockIndexFromTProgram(uniform.index) < 0) return 0;
-            const glslang::TType* type = uniform.getType();
-            if (type == nullptr || !type->isMatrix()) return 0;
-            glslang::TLayoutMatrix layoutMatrix = type->getQualifier().layoutMatrix;
-            if (layoutMatrix == glslang::ElmNone) {
-                layoutMatrix = Artifacts().program->getUniformBlock(uniform.index).getType()->getQualifier().layoutMatrix;
-            }
-            return (layoutMatrix == glslang::ElmRowMajor) ? 1 : 0;
+            if (!uniform.type.isMatrix) return 0;
+            // layoutMatrix is already resolved against the owning block's qualifier at
+            // snapshot time, so the getUniformBlock() fallback this used to carry is gone.
+            return (uniform.type.layoutMatrix == static_cast<Int>(glslang::ElmRowMajor)) ? 1 : 0;
         }
 
         // GL_UNIFORM_MATRIX_STRIDE: byte stride between columns (col-major) / rows (row-major) of a
@@ -290,16 +354,11 @@ namespace MobileGL::MG_State::GLState {
         // out as std140 (packed/shared are coerced), so this matches the offsets glslang reports. For
         // every GL 3.3 float matrix this evaluates to 16, independent of majorness.
         GLint GetActiveUniformMatrixStride(Uint index) const {
-            const auto& uniform = Artifacts().program->getUniform(TProgramUniformIndex(index));
+            const auto& uniform = UniformAt(TProgramUniformIndex(index));
             if (GlBlockIndexFromTProgram(uniform.index) < 0) return -1;
-            const glslang::TType* type = uniform.getType();
-            if (type == nullptr || !type->isMatrix()) return 0;
-            glslang::TLayoutMatrix layoutMatrix = type->getQualifier().layoutMatrix;
-            if (layoutMatrix == glslang::ElmNone) {
-                layoutMatrix = Artifacts().program->getUniformBlock(uniform.index).getType()->getQualifier().layoutMatrix;
-            }
-            const bool rowMajor = (layoutMatrix == glslang::ElmRowMajor);
-            const int strideVectorComponents = rowMajor ? type->getMatrixCols() : type->getMatrixRows();
+            if (!uniform.type.isMatrix) return 0;
+            const bool rowMajor = (uniform.type.layoutMatrix == static_cast<Int>(glslang::ElmRowMajor));
+            const int strideVectorComponents = rowMajor ? uniform.type.matrixCols : uniform.type.matrixRows;
             constexpr int scalarSize = 4; // GL 3.3 core uniform matrices are float
             const int vectorAlignment = (strideVectorComponents <= 1)   ? scalarSize
                                         : (strideVectorComponents == 2) ? 2 * scalarSize
@@ -307,21 +366,39 @@ namespace MobileGL::MG_State::GLState {
             return (vectorAlignment + 15) & ~15; // std140 round-up to a vec4
         }
 
-        const glslang::TType* GetUniformTType(Uint location) const {
-            auto& uniform = Artifacts().program->getUniform(Artifacts().uniformIndexInTProgram[location]);
-            return uniform.getType();
+        // The flattened type of the uniform at `location`. This is what replaced
+        // GetUniformTType(): the same information, owned by the program instead of by a
+        // glslang pool, so it stays valid for a link served from the L1 translation memo.
+        const TypeFacts& GetUniformTypeFacts(Uint location) const {
+            return UniformAt(Artifacts().uniformIndexInTProgram[location]).type;
         }
 
-        Bool IsUniformOpaqueAtLocation(Uint location) const { return GetUniformTType(location)->isOpaque(); }
+        // Replaces GetUniformTType(), which used to hand a raw glslang::TType* - into a
+        // pool the program no longer necessarily owns - out to the DirectGLES image-format
+        // bake. These are the only three things any caller ever read off it.
+        Bool UniformHasDeclaredImageFormat(Uint location) const {
+            return UniformAt(Artifacts().uniformIndexInTProgram[location]).type.hasFormat;
+        }
+        Uint GetUniformDeclaredImageFormat(Uint location) const {
+            return UniformAt(Artifacts().uniformIndexInTProgram[location]).type.layoutFormat;
+        }
+        // Matrix column count, 0 for a non-matrix. The global-UBO fallback allocator sizes a
+        // matrix slot from it.
+        Int GetUniformMatrixColumns(Uint location) const {
+            const auto& uniform = UniformAt(Artifacts().uniformIndexInTProgram[location]);
+            return uniform.type.isMatrix ? uniform.type.matrixCols : 0;
+        }
+
+        Bool IsUniformOpaqueAtLocation(Uint location) const {
+            return UniformAt(Artifacts().uniformIndexInTProgram[location]).type.isOpaque;
+        }
 
         const String& GetUniformName(Uint location) const {
-            auto& uniform = Artifacts().program->getUniform(Artifacts().uniformIndexInTProgram[location]);
-            return uniform.name;
+            return UniformAt(Artifacts().uniformIndexInTProgram[location]).name;
         }
 
         const String& GetActiveUniformName(Uint index) const {
-            auto& uniform = Artifacts().program->getUniform(TProgramUniformIndex(index));
-            return uniform.name;
+            return UniformAt(TProgramUniformIndex(index)).name;
         }
         // Sentinel for a uniform location without global-UBO backing storage (should not
         // survive linking: GenerateBinary falls back to tail-allocated scratch storage).
@@ -355,17 +432,17 @@ namespace MobileGL::MG_State::GLState {
         // would, half its GL type size, and a `dmat4` is padded like any other matrix. Anything
         // reading or writing a whole uniform's storage - a bounds check, a copy between two
         // programs' shadows - wants this rather than GetUniformSizesInBytes.
-        static SizeT UniformStorageSpanInBytes(const glslang::TType* type, SizeT tightSize) {
-            if (type != nullptr && type->isMatrix()) {
-                return static_cast<SizeT>(type->getMatrixCols()) * 4 * sizeof(Float);
+        static SizeT UniformStorageSpanInBytes(const TypeFacts& type, SizeT tightSize) {
+            if (type.isMatrix) {
+                return static_cast<SizeT>(type.matrixCols) * 4 * sizeof(Float);
             }
-            if (type != nullptr && type->getBasicType() == glslang::EbtDouble) {
+            if (type.isDouble) {
                 return tightSize / 2;
             }
             return tightSize;
         }
         SizeT GetUniformStorageSpanInBytes(Uint location) const {
-            return UniformStorageSpanInBytes(GetUniformTType(location), GetUniformSizesInBytes(location));
+            return UniformStorageSpanInBytes(GetUniformTypeFacts(location), GetUniformSizesInBytes(location));
         }
 
         // ---- "written since link": the per-location dirty set the pipeline composite mirrors from ----
@@ -476,14 +553,14 @@ namespace MobileGL::MG_State::GLState {
             return mask;
         }
         Uint32 GetActiveFragmentOutputLocationMask() const {
-            if (!Artifacts().program) {
+            if (Artifacts().pipeOutputReflection.empty()) {
                 return 0;
             }
 
             Uint32 mask = 0;
-            const Int outputCount = Artifacts().program->getNumPipeOutputs();
+            const Int outputCount = static_cast<Int>(Artifacts().pipeOutputReflection.size());
             for (Int index = 0; index < outputCount; ++index) {
-                const Int location = static_cast<Int>(Artifacts().program->getPipeOutput(index).layoutLocation());
+                const Int location = Artifacts().pipeOutputReflection[index].location;
                 if (location >= 0 && location < 32) {
                     mask |= (1u << location);
                 }
@@ -491,38 +568,34 @@ namespace MobileGL::MG_State::GLState {
             return mask;
         }
         Int GetActiveFragmentOutputCount() const {
-            return Artifacts().program ? Artifacts().program->getNumPipeOutputs() : 0;
+            return static_cast<Int>(Artifacts().pipeOutputReflection.size());
         }
         const String& GetActiveFragmentOutputName(Uint index) const {
-            MOBILEGL_ASSERT(Artifacts().program != nullptr, "ProgramObject::GetActiveFragmentOutputName: program is null");
-            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().program->getNumPipeOutputs()),
+            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().pipeOutputReflection.size()),
                             "ProgramObject::GetActiveFragmentOutputName: index=%u out of range", index);
-            return Artifacts().program->getPipeOutput(static_cast<Int>(index)).name;
+            return Artifacts().pipeOutputReflection[index].name;
         }
         Int GetFragmentOutputLocation(Uint index) const {
-            MOBILEGL_ASSERT(Artifacts().program != nullptr, "ProgramObject::GetFragmentOutputLocation: program is null");
-            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().program->getNumPipeOutputs()),
+            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().pipeOutputReflection.size()),
                             "ProgramObject::GetFragmentOutputLocation: index=%u out of range",
                             index);
-            return static_cast<Int>(Artifacts().program->getPipeOutput(static_cast<Int>(index)).layoutLocation());
+            return Artifacts().pipeOutputReflection[index].location;
         }
         GLint GetActiveFragmentOutputArraySize(Uint index) const {
-            MOBILEGL_ASSERT(Artifacts().program != nullptr, "ProgramObject::GetActiveFragmentOutputArraySize: program is null");
-            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().program->getNumPipeOutputs()),
+            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().pipeOutputReflection.size()),
                             "ProgramObject::GetActiveFragmentOutputArraySize: index=%u out of range", index);
-            return Artifacts().program->getPipeOutput(static_cast<Int>(index)).size;
+            return Artifacts().pipeOutputReflection[index].size;
         }
         GLenum GetFragmentOutputType(Uint index) const {
-            MOBILEGL_ASSERT(Artifacts().program != nullptr, "ProgramObject::GetFragmentOutputType: program is null");
-            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().program->getNumPipeOutputs()),
+            MOBILEGL_ASSERT(index < static_cast<Uint>(Artifacts().pipeOutputReflection.size()),
                             "ProgramObject::GetFragmentOutputType: index=%u out of range",
                             index);
-            return Artifacts().program->getPipeOutput(static_cast<Int>(index)).glDefineType;
+            return Artifacts().pipeOutputReflection[index].glDefineType;
         }
         GLenum GetAttribType(Uint index) const { return Artifacts().attribTypes[index]; }
         const String& GetAttribName(Uint index) const { return Artifacts().attribs[index]; }
-        GLenum GetActiveAttribType(Uint index) const { return Artifacts().program->getPipeInput(static_cast<Int>(index)).glDefineType; }
-        GLint GetActiveAttribArraySize(Uint index) const { return Artifacts().program->getPipeInput(static_cast<Int>(index)).size; }
+        GLenum GetActiveAttribType(Uint index) const { return Artifacts().pipeInputReflection[index].glDefineType; }
+        GLint GetActiveAttribArraySize(Uint index) const { return Artifacts().pipeInputReflection[index].size; }
         // The Vulkan-semantics parse reflects the vertex builtins under their SPIR-V names;
         // GL must keep reporting the GL spellings (glGetActiveAttrib and the program-input
         // resource queries enumerate builtins).
@@ -534,7 +607,7 @@ namespace MobileGL::MG_State::GLState {
             return name;
         }
         const String& GetActiveAttribName(Uint index) const {
-            return NormalizeBuiltinPipeInputName(Artifacts().program->getPipeInput(static_cast<Int>(index)).name);
+            return NormalizeBuiltinPipeInputName(Artifacts().pipeInputReflection[index].name);
         }
         // PHASE B, all three (see EnsureSpirvJoined): the shadow buffer's layout is decided
         // by the OPTIMIZED SPIR-V, so it does not exist until the SPIR-V job has settled - and
@@ -627,7 +700,7 @@ namespace MobileGL::MG_State::GLState {
             // which means the change is only honoured by regenerating the program. That
             // regeneration is gated on link-shaped versions, so without a counter that moves
             // here the new unit would never reach the driver.
-            if (const glslang::TType* type = GetUniformTType(location); type != nullptr && type->isImage()) {
+            if (GetUniformTypeFacts(location).isImage) {
                 ++m_imageUnitVersion;
             }
         }
@@ -702,20 +775,14 @@ namespace MobileGL::MG_State::GLState {
         // SIGSEGV inside glslang::TProgram::getNumPipeInputs - KHR-GL30.api.coverage does exactly
         // this after a failed glGetAttribLocation, and reached it as soon as the CopyTexImage2D
         // throw ahead of it stopped killing the run first.
-        Int GetActiveAtomicCounterCount() const {
-            const auto& program = Artifacts().program;
-            return program ? program->getNumAtomicCounters() : 0;
-        }
         Int GetActiveAttributesCount() const {
-            const auto& program = Artifacts().program;
-            return program ? program->getNumPipeInputs() : 0;
+            return static_cast<Int>(Artifacts().pipeInputReflection.size());
         }
         // GL-visible uniform blocks only: the synthesized MGL_GLOBAL_UBO the relaxed parse
         // materializes for default-block uniforms is filtered out by DoReflection.
         Int GetActiveUniformBlocksCount() const { return static_cast<Int>(Artifacts().glBlockIndexToTProgram.size()); }
         GLuint GetComputeLocalSize(Uint dim) const {
-            const auto& program = Artifacts().program;
-            return program ? program->getLocalSize(static_cast<Int>(dim)) : 0;
+            return dim < 3u ? Artifacts().computeLocalSize[dim] : 0u;
         }
         Int GetActiveAttributesMaxLength() const { return Artifacts().attribInNameMaxLength; }
         Int GetActiveUniformBlocksMaxNameLength() const { return Artifacts().uniformBlockNameMaxLength; }
@@ -739,11 +806,11 @@ namespace MobileGL::MG_State::GLState {
             // (like a std140 struct) occupies a vec4-rounded size, and that is what the
             // backend compiles: ES drivers reject draws whose bound UBO range is smaller
             // than the block (a block ending in ivec3 reported 12 while the driver needs 16).
-            return (Artifacts().program->getUniformBlock(Artifacts().glBlockIndexToTProgram[index]).size + 15u) & ~15u;
+            return (static_cast<Uint>(BlockAt(Artifacts().glBlockIndexToTProgram[index]).size) + 15u) & ~15u;
         }
 
         const String& GetUniformBlockName(Uint index) const {
-            auto& ubo = Artifacts().program->getUniformBlock(Artifacts().glBlockIndexToTProgram[index]);
+            const auto& ubo = BlockAt(Artifacts().glBlockIndexToTProgram[index]);
             return ubo.name;
         }
 
@@ -774,7 +841,7 @@ namespace MobileGL::MG_State::GLState {
         }
 
         Bool IsUniformBlockReferencedByStage(Uint index, EShLanguage stage) const {
-            const auto& ubo = Artifacts().program->getUniformBlock(Artifacts().glBlockIndexToTProgram[index]);
+            const auto& ubo = BlockAt(Artifacts().glBlockIndexToTProgram[index]);
             const auto stageMask = static_cast<EShLanguageMask>(1 << stage);
             return (ubo.stages & stageMask) != 0;
         }
@@ -855,8 +922,6 @@ namespace MobileGL::MG_State::GLState {
         // (MG_Impl/GLImpl/Program/ProgramInterface.cpp), which has to enumerate buffer
         // blocks, buffer variables, atomic counters and per-stage reference masks. Null
         // until a link has succeeded. Read through the join gate like everything else.
-        const glslang::TProgram* GetReflection() const { return Artifacts().program.get(); }
-
         Int GetShaderIndexByStage(ShaderStage stage) const {
             auto it = std::find_if(m_shaders.begin(), m_shaders.end(), [stage](const SharedPtr<ShaderObject>& shader) {
                 return shader->GetShaderStage() == stage;
@@ -909,9 +974,50 @@ namespace MobileGL::MG_State::GLState {
         // what makes "every read of link output joins the pending link" a property the
         // compiler checks rather than a review item - a new reader cannot spell the field
         // without going through the gate.
+        // ---- the owned mirror of glslang's reflection ----
+        //
+        // WHY THIS EXISTS. Every GL query about a linked program used to be answered by
+        // asking the live glslang::TProgram - program->getUniform(i).getType()->isMatrix()
+        // and friends. That made the TProgram part of the program's PERMANENT state, which
+        // in turn made the whole front end (parse + link) unskippable: the L1 shader
+        // translation memo could hand back the SPIR-V but the reflection still had to be
+        // rebuilt from a freshly parsed AST.
+        //
+        // These three tables are a snapshot of everything the query surface ever reads off
+        // the TProgram, in PLAIN OWNED VALUES - no TType*, no TString, nothing pointing into
+        // a glslang pool. Taken once at the tail of DoReflection (SnapshotGlslangReflection),
+        // they are copyable, immutable after the link, and safe to memoize and share between
+        // ProgramObjects and threads. Once they are filled, `program` is dead weight to
+        // everything except DoReflection itself.
+        //
+        // INDEXED BY TPROGRAM INDEX, deliberately: that is the space uniformIndexInTProgram,
+        // glUniformIndexToTProgram and tProgramUniformIndexToGl already speak, so every
+        // accessor that used to call program->getUniform(i) indexes uniformReflection[i]
+        // instead, unchanged in every other respect.
+
         struct LinkArtifacts {
+            // Live only between LinkProgram() and the end of DoReflection. Everything after
+            // that reads the owned mirror below; a link served from the L1 memo never
+            // constructs one at all, so this is null for such a program and MUST NOT be
+            // dereferenced outside DoReflection.
             SharedPtr<glslang::TProgram> program;
 
+            // The owned reflection snapshot. Indexed by TProgram index; see the structs above.
+            Vector<UniformReflection> uniformReflection;
+            Vector<BlockReflection> blockReflection;
+            Vector<PipeInputReflection> pipeInputReflection;
+            Vector<PipeOutputReflection> pipeOutputReflection;
+            // Program-level scalars glslang answers off the linked intermediates.
+            // Whether the program's LAST stage is the fragment stage. A color number - and so a
+            // color index - exists only there; a separable tess/geometry/vertex program's
+            // outputs are varyings and must report -1 (KHR-GL43.program_interface_query.
+            // separate-programs-tess-control).
+            Bool lastStageIsFragment = false;
+            Array<GLuint, 3> computeLocalSize{};
+            // Replaces program->getUniformIndex(name). Maps the reflected name to its
+            // TProgram uniform index.
+            UnorderedMap<String, Int> uniformIndexByName;
+
             // Attributes (Vertex in)
             Vector<String> attribs;
             Vector<GLenum> attribTypes;
@@ -1042,6 +1148,14 @@ namespace MobileGL::MG_State::GLState {
         // ordering is explicit and nothing is exempt.
         static void ResetLinkArtifacts(LinkArtifacts& artifacts);
 
+        // The owned reflection snapshot, for the program-interface query layer. Replaces
+        // GetReflection(), which handed out the live glslang::TProgram - the last thing that
+        // forced a linked program to keep its parse alive.
+        const LinkArtifacts& GetLinkReflection() const {
+            EnsureLinkJoined();
+            return Artifacts();
+        }
+
         static Bool IsValidUniformLocation(const LinkArtifacts& artifacts, Int location) {
             if (location < 0 || location > static_cast<Int>(artifacts.maxUniformLocation)) return false;
             if (static_cast<SizeT>(location) >= artifacts.uniformIndexInTProgram.size()) return false;
@@ -1057,12 +1171,24 @@ namespace MobileGL::MG_State::GLState {
         // for both. GL 3.3 core uniforms are always sized. Takes a TProgram uniform index (the space
         // the artifacts' uniformIndexInTProgram stores).
         static GLint GetUniformArraySizeByTIndex(const LinkArtifacts& artifacts, Int tIndex) {
-            const auto& uniform = artifacts.program->getUniform(tIndex);
-            const glslang::TType* type = uniform.getType();
-            if (type != nullptr && type->isSizedArray()) {
-                return type->getOuterArraySize();
+            return UniformAtIn(artifacts, tIndex).arraySize;
+        }
+
+        // Bounds-checked mirror lookup. Out of range yields a default-constructed entry
+        // rather than UB, which is the same shape the phase-B getters use: a program whose
+        // reflection is missing must stay answerable, not crash the query surface.
+        static const UniformReflection& UniformAtIn(const LinkArtifacts& artifacts, Int tIndex) {
+            static const UniformReflection kEmpty;
+            if (tIndex < 0 || static_cast<SizeT>(tIndex) >= artifacts.uniformReflection.size()) return kEmpty;
+            return artifacts.uniformReflection[tIndex];
+        }
+        const UniformReflection& UniformAt(Int tIndex) const { return UniformAtIn(Artifacts(), tIndex); }
+        const BlockReflection& BlockAt(Int tBlockIndex) const {
+            static const BlockReflection kEmpty;
+            if (tBlockIndex < 0 || static_cast<SizeT>(tBlockIndex) >= Artifacts().blockReflection.size()) {
+                return kEmpty;
             }
-            return uniform.size < 1 ? 1 : uniform.size;
+            return Artifacts().blockReflection[tBlockIndex];
         }
 
         // Blocks until a pending link has published its artifacts. Public because a few call

MobileGL/MG_State/GLState/ProgramState/ProgramSpirvTask.cpp

@@ -12,6 +12,8 @@
 #include <MG_Util/Async/ShaderCompilePool.h>
 #include <MG_Util/ShaderTranspiler/ShaderCompiler.h>
 #include <MG_Util/ShaderTranspiler/SpvcSession.h>
+#include <MG_State/GLState/ProgramState/ProgramTranslationCache.h>
+#include <MG_Util/ShaderTranspiler/TranslationCache.h>
 #include <MG_Util/ShaderTranspiler/Types.h>
 
 #include <cstring>
@@ -95,11 +97,25 @@ namespace MobileGL::MG_State::GLState {
         // and `diagnostics`, and this node is the sole reader of the handoff.
         ProgramLinkTask::SpirvHandoff& handoff = m_phaseA->spirvHandoff;
         const Uint externalIndex = m_phaseA->in.externalIndex;
-        if (!handoff.ready || !handoff.reflection.program) {
+        if (!handoff.ready) {
             // Phase A did not reach its tail (it failed the link, or was cancelled mid-body).
             // Publish nothing; spirvStatus stays false.
             return;
         }
+        // A TProgram is required only to GENERATE. A link served from the L1 memo has none by
+        // construction - that is the entire point of the widened payload - and its SPIR-V and
+        // routing tables arrive ready-made in cachedSpirv.
+        if (!handoff.cachedSpirv && !handoff.reflection.program) return;
+
+        // An L1 hit already carries everything this phase would have produced. Publish it
+        // and stop: no GlslangToSpv, no spirv-opt, no routing pass.
+        if (handoff.cachedSpirv) {
+            artifacts = *handoff.cachedSpirv;
+            MGLOG_D("ProgramObject %u: L1 cache hit - %zu SPIR-V module(s) and the global-UBO "
+                    "routing reused",
+                    externalIndex, artifacts.generatedSpirv.size());
+            return;
+        }
 
         MGLOG_D("ProgramObject %u: Starting SPIR-V generation", externalIndex);
         const Bool deferOutputValidationForDirectVulkan =
@@ -117,13 +133,18 @@ namespace MobileGL::MG_State::GLState {
         //   * CAS-LOSER shaders (the re-parse in ShaderCompileTask::ClaimParsedShader, i.e.
         //     the 2nd..Nth link of a shared shader): freed here in full. The handoff is their
         //     ONLY owner.
-        //   * CAS-WINNER shaders (the common case - one shader object linked into one
-        //     program, which is every program of an Iris pack load): NOT freed here. The
-        //     winner branch returns a COPY of ShaderCompileTask::artifacts.shader
-        //     (ShaderCompileTask.cpp:320) and the node never releases its own reference, while
-        //     phase A holds that node through in.shaders[i].compiled for its whole life - and
-        //     phase A lives until PhaseAReleaser fires at the end of this body. So the
-        //     refcount goes 2 -> 1 here and the arena dies where it would have died anyway.
+        //   * L1c-HIT shaders (the compile published a verdict and never parsed, so the parse
+        //     was made on demand by ClaimParsedShader): freed here in full, exactly like a
+        //     CAS loser and for the same reason - the handoff is their only owner. This
+        //     category did not exist before the translation memo's compile half, and it makes
+        //     the clear below strictly more effective than the paragraph below describes.
+        //   * CAS-WINNER shaders (one shader object linked into one program, whose compile
+        //     MISSED L1c and therefore stored its parse): NOT freed here. The winner branch
+        //     returns a COPY of ShaderCompileTask::artifacts.shader and the node never
+        //     releases its own reference, while phase A holds that node through
+        //     in.shaders[i].compiled for its whole life - and phase A lives until
+        //     PhaseAReleaser fires at the end of this body. So the refcount goes 2 -> 1 here
+        //     and the arena dies where it would have died anyway.
         //
         // Making it free the winner's arena too means releasing whatever pins the TShader
         // inside the compile node, and neither obvious route is safe as a drive-by: moving out
@@ -137,6 +158,23 @@ namespace MobileGL::MG_State::GLState {
 
         MGLOG_D("ProgramObject %u: Building global-UBO routing tables", externalIndex);
         BuildGlobalUboRouting(handoff, externalIndex);
+
+        // The completed front end goes into the L1 memo HERE, where both halves exist: phase
+        // A's LinkArtifacts (carried in the handoff) and this phase's SpirvArtifacts.
+        //
+        // Only a clean run is memoized. A failed optimizer run leaves a module as whatever the
+        // chain got to before it gave up, and that is exactly the binary no other program
+        // should ever be handed.
+        if (artifacts.spirvStatus && handoff.spirvCacheKey.Valid() && handoff.linkArtifactsForCache) {
+            auto payload = MakeShared<ProgramTranslationResult>();
+            payload->link = *handoff.linkArtifactsForCache;
+            payload->link.program.reset(); // belt and braces: never memoize a glslang arena
+            payload->spirv = artifacts;
+            const SizeT payloadBytes = ProgramTranslationResultBytes(*payload);
+            GetProgramTranslationCache().Insert(handoff.spirvCacheKey,
+                                                ProgramTranslationResultPtr(Move(payload)),
+                                                payloadBytes);
+        }
         MGLOG_D("ProgramObject %u: Binary generation finished (generatedSpirv size=%zu)", externalIndex,
                 artifacts.generatedSpirv.size());
     }
@@ -296,22 +334,25 @@ namespace MobileGL::MG_State::GLState {
         for (Uint location = 0; location <= reflection.maxUniformLocation; ++location) {
             if (artifacts.uniformOffsets[location] != ProgramObject::kInvalidUniformOffset) continue;
             if (!ProgramObject::IsValidUniformLocation(reflection, static_cast<Int>(location))) continue;
-            const auto& uniform = reflection.program->getUniform(reflection.uniformIndexInTProgram[location]);
-            const glslang::TType* type = uniform.getType();
-            if (type != nullptr && type->isOpaque()) continue;
-            if (uniform.index >= 0 && uniform.index < reflection.program->getNumUniformBlocks() &&
-                std::strstr(reflection.program->getUniformBlock(uniform.index).name.c_str(),
-                            MG_Util::ShaderTranspiler::GLOBAL_UBO_NAME) == nullptr) {
-                // Member of a named uniform block: not settable through glUniform*, so it
-                // needs no global-UBO shadow storage.
+            const auto& uniform =
+                ProgramObject::UniformAtIn(reflection, reflection.uniformIndexInTProgram[location]);
+            if (uniform.type.isOpaque) continue;
+            // Member of a named uniform block: not settable through glUniform*, so it needs
+            // no global-UBO shadow storage. tProgramBlockIndexToGl[i] >= 0 means block i is
+            // GL-visible, i.e. NOT the synthesized MGL_GLOBAL_UBO - which is exactly what the
+            // strstr(GLOBAL_UBO_NAME) test this replaced was asking, without needing the
+            // TProgram to spell the block name.
+            if (uniform.index >= 0 &&
+                uniform.index < static_cast<Int>(reflection.tProgramBlockIndexToGl.size()) &&
+                reflection.tProgramBlockIndexToGl[uniform.index] >= 0) {
                 continue;
             }
 
             // std140-style slot: the matrix upload paths write column vectors at
             // 16-byte strides, so a matrix slot must cover cols * 16 bytes.
             SizeT slotSize = MG_Util::GetGLTypeSize(uniform.glDefineType);
-            if (type != nullptr && type->isMatrix()) {
-                slotSize = static_cast<SizeT>(type->getMatrixCols()) * 16u;
+            if (uniform.type.isMatrix) {
+                slotSize = static_cast<SizeT>(uniform.type.matrixCols) * 16u;
             }
             slotSize = (slotSize + 15u) & ~static_cast<SizeT>(15u);
             const SizeT slotOffset = (artifacts.globalUboScratch.size() + 15u) & ~static_cast<SizeT>(15u);

MobileGL/MG_State/GLState/ProgramState/ProgramTranslationCache.cpp

@@ -0,0 +1,82 @@
+// MobileGL - MobileGL/MG_State/GLState/ProgramState/ProgramTranslationCache.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+
+#include "ProgramTranslationCache.h"
+
+namespace MobileGL::MG_State::GLState {
+    namespace {
+        // ---- L1 caps: 48 entries / 24 MiB ----
+        //
+        // Both numbers moved when the payload grew from "the SPIR-V modules" to "the whole
+        // front end". An entry is now the stages' preprocessed source (the key), the SPIR-V,
+        // the reflection snapshot and the global-UBO shadow - roughly twice what it was - so
+        // the byte budget doubled and the entry count came down to keep the worst case in the
+        // same place on a phone.
+        //
+        // The shape of the choice has not changed: this cache exists for REPETITION, not
+        // coverage. A KHR-GL33.texture_swizzle smoke case builds 2592 programs out of fewer
+        // than ten distinct ones, so a handful of entries serves it completely; an Iris
+        // shaderpack load is ~300-600 MOSTLY DISTINCT programs that would never hit however
+        // large the cache is, so a bigger cap there buys nothing and costs resident memory.
+        // 48 is comfortably above the distinct-program count of every repetition workload
+        // measured, and 24 MiB bounds the pathological case - a pack whose ~100 KB stages
+        // really are re-linked - at roughly three times the existing 8 MiB
+        // ShaderPreprocessCache budget, which is the other memo on this path.
+        constexpr SizeT kMaxEntries = 48;
+        constexpr SizeT kMaxBytes = 24u * 1024u * 1024u;
+
+        SizeT StringsBytes(const Vector<String>& values) {
+            SizeT bytes = 0;
+            for (const String& value : values) bytes += value.size() + sizeof(String);
+            return bytes;
+        }
+
+        SizeT ResourcesBytes(const Vector<ProgramObject::ResourceReflection>& records) {
+            SizeT bytes = records.size() * sizeof(ProgramObject::ResourceReflection);
+            for (const auto& record : records) bytes += record.name.size();
+            return bytes;
+        }
+    } // namespace
+
+    // Approximate on purpose: it feeds a budget, not an allocator. It counts the things that
+    // actually scale with shader size - the SPIR-V, the reflection names, the UBO shadow -
+    // and ignores per-entry fixed overhead.
+    SizeT ProgramTranslationResultBytes(const ProgramTranslationResult& result) {
+        SizeT bytes = 0;
+        for (const auto& module : result.spirv.generatedSpirv) bytes += module.size() * sizeof(unsigned);
+        bytes += result.spirv.uniformOffsets.size() * sizeof(Uint);
+        bytes += result.spirv.globalUboScratch.size();
+        bytes += ResourcesBytes(result.link.uniformReflection);
+        bytes += ResourcesBytes(result.link.blockReflection);
+        bytes += ResourcesBytes(result.link.pipeInputReflection);
+        bytes += ResourcesBytes(result.link.pipeOutputReflection);
+        bytes += StringsBytes(result.link.attribs);
+        bytes += StringsBytes(result.link.xfbInterfaceNames);
+        bytes += result.link.infoLog.size();
+        return bytes;
+    }
+
+    MG_Util::ShaderTranspiler::BoundedTranslationCache<ProgramTranslationResult>&
+    GetProgramTranslationCache() {
+        // DELIBERATELY LEAKED - see the same note on the L2 cache in
+        // MG_Util/ShaderTranspiler/TranslationCache.cpp. A function-local static OBJECT
+        // registers its destructor at first use, and first use here is a ShaderCompilePool
+        // worker; ShaderCompilePool's own atexit drain sentinel is registered strictly
+        // earlier, and exit handlers run in reverse order - so the cache would be destroyed
+        // while workers were still inserting into it. A function-local static POINTER is
+        // trivially destructible and registers no exit handler at all.
+        static auto* const kCache =
+            new MG_Util::ShaderTranspiler::BoundedTranslationCache<ProgramTranslationResult>(
+                "ShaderTranslationCache L1 (GLSL->front end)", kMaxEntries, kMaxBytes);
+        return *kCache;
+    }
+
+    void ClearProgramTranslationCache() { GetProgramTranslationCache().Clear(); }
+
+    void LogProgramTranslationCacheStats() { GetProgramTranslationCache().LogStats(); }
+} // namespace MobileGL::MG_State::GLState

MobileGL/MG_State/GLState/ProgramState/ProgramTranslationCache.h

@@ -0,0 +1,69 @@
+// MobileGL - MobileGL/MG_State/GLState/ProgramState/ProgramTranslationCache.h
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+
+#pragma once
+#include <Includes.h>
+#include <MG_State/GLState/ProgramState/ProgramObject.h>
+#include <MG_Util/ShaderTranspiler/TranslationCache.h>
+
+namespace MobileGL::MG_State::GLState {
+    // ===================================================================================
+    // L1 of the shader translation memo: THE WHOLE FRONT END of one glLinkProgram.
+    //
+    // A hit skips the glslang link and mapIO, GlslangToSpv, the 11-pass
+    // SanitizeAndOptimizeBinary chain, buildReflection, and the global-UBO routing pass. No
+    // TProgram is constructed at all - which is only possible because the GL query surface no
+    // longer reads one (see ProgramObject::UniformReflection and
+    // ProgramLinkTask::SnapshotGlslangReflection).
+    //
+    // IT DOES NOT SKIP THE PARSE, and no widening of this payload could: the parse belongs to
+    // glCompileShader, a different entry point one job earlier, and it has already run by the
+    // time a link looks this key up. Skipping it is L1c's job - the compile half of the memo,
+    // in MG_Util/ShaderTranspiler/TranslationCache.h. The two together are what make a
+    // repeated program build construct no glslang object of any kind; either one alone leaves
+    // roughly half the front end on the hot path (~322 us of parse against a ~650 us
+    // CTS-shaped program build, and 1.45-1.48x measured on device with L1 alone).
+    //
+    // WHY THE PAYLOAD IS THE WHOLE THING rather than just the SPIR-V: the frontend answers
+    // glGetActiveUniform, glGetProgramResource*, glGetUniformLocation and the rest out of
+    // LinkArtifacts, and glUniform*/glGetUniform* out of SpirvArtifacts. Caching only the
+    // modules would have left the link on the hot path to rebuild exactly the data the
+    // payload can carry.
+    //
+    // WHY IT LIVES HERE AND NOT IN MG_Util: the payload is a ProgramObject::LinkArtifacts
+    // plus a ProgramObject::SpirvArtifacts, and MG_Util must not depend on MG_State. The
+    // KEY is plain bytes and stays in MG_Util (BuildSpirvTranslationKey), so both layers
+    // agree on exactly one definition of "the same front-end input".
+    //
+    // EVERYTHING IN THE PAYLOAD IS PLAIN OWNED DATA. `link.program` is null by construction:
+    // the whole point is that a hit never has a glslang arena to point into. Both structs
+    // were audited field by field - the only member that ever pointed into glslang-owned
+    // memory was `program` itself, and TUniformInitializer / XfbVarying, which look like
+    // glslang types, are std::string + std::vector aggregates.
+    struct ProgramTranslationResult {
+        // program == nullptr, always. Asserted at insert.
+        ProgramObject::LinkArtifacts link;
+        ProgramObject::SpirvArtifacts spirv;
+    };
+    using ProgramTranslationResultPtr = SharedPtr<const ProgramTranslationResult>;
+
+    SizeT ProgramTranslationResultBytes(const ProgramTranslationResult& result);
+
+    // Process-global, and safe to be: the FRONT-END environment fingerprint is in the key
+    // (see CompileEnv::frontendFingerprint), so a program built under one context's glslang
+    // limits can never be handed to a context with different ones - while two contexts on
+    // DIFFERENT GPUs that agree on those limits deliberately share entries.
+    //
+    // Global rather than per-context because the producer runs on a ShaderCompilePool worker
+    // and must not reach MG_State::pGLContext.
+    MG_Util::ShaderTranspiler::BoundedTranslationCache<ProgramTranslationResult>&
+    GetProgramTranslationCache();
+
+    void ClearProgramTranslationCache();
+    void LogProgramTranslationCacheStats();
+} // namespace MobileGL::MG_State::GLState

MobileGL/MG_State/GLState/ProgramState/ShaderCompileTask.cpp

@@ -8,13 +8,16 @@
 
 #include "ShaderCompileTask.h"
 
+#include <MG_State/GLState/BufferState/BufferState.h>
 #include <MG_Util/Converters/MGToGL/ProgramEnumConverter.h>
 #include <MG_Util/ShaderTranspiler/ShaderCompiler.h>
 #include <MG_Util/ShaderTranspiler/ShaderSourceProcessor.h>
+#include <MG_Util/ShaderTranspiler/TranslationCache.h>
 #include <MG_Util/ShaderTranspiler/Types.h>
 
 #include <glslang/Include/PoolAlloc.h>
 
+#include <algorithm>
 #include <charconv>
 
 namespace {
@@ -137,8 +140,21 @@ namespace {
         return std::nullopt;
     }
 
+    // What glGetIntegerv(GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS) answers, recomputed rather than
+    // queried: the compile runs on a worker with no context, and the pname is not a plain backend
+    // parameter - the getter caps the backend's count by the state layer's fixed binding-point
+    // array (GL_Getter's GetIndexedBufferQueryPointCount). A shader must be judged against the
+    // number the application was told, not against either half of it.
+    static MobileGL::Int MaxShaderStorageBufferBindings(
+        const MobileGL::MG_Util::ShaderTranspiler::CompileEnv& env) {
+        const MobileGL::Int frontendPoints =
+            static_cast<MobileGL::Int>(MobileGL::MG_State::GLState::BufferBindingPointCount);
+        if (!env.HasBackend()) return frontendPoints;
+        return std::min<MobileGL::Int>(frontendPoints, std::max<MobileGL::Int>(env.params.MaxShaderStorageBufferBindings, 0));
+    }
+
     // The half of a compile that depends on nothing but the source text, the stage and the
-    // environment snapshot: preprocessing, the two lexical rejections, and the two lexical
+    // environment snapshot: preprocessing, the three lexical rejections, and the two lexical
     // side-channel extractions. Split out so P0b layer 2 can memoize exactly this and
     // nothing else - the glslang parse stays per-object because its TShader is consume-once.
     // Deliberately free of any per-object state so the memo is sound.
@@ -172,6 +188,13 @@ namespace {
             return result;
         }
 
+        if (const std::optional<String> bindingError = FindShaderStorageBindingViolation(
+                result.preprocessedSource, MaxShaderStorageBufferBindings(env))) {
+            result.outcome = ShaderPreprocessOutcome::ResourceBindingRejected;
+            result.infoLog = *bindingError;
+            return result;
+        }
+
         // The parse this feeds runs in the link-compatible configuration (Vulkan-client
         // env with relaxed rules): the TShader it produces is what glLinkProgram links and
         // what the backends' SPIR-V is generated from - there is no second, GL-client
@@ -248,17 +271,80 @@ namespace MobileGL::MG_State::GLState {
             return;
         }
 
-        ShaderAttrib attrib{.shaderType = MG_Util::ConvertShaderStageToGLEnum(stage),
-                            .sourceStr = shared.preprocessedSource,
-                            .flags = 0,
-                            .env = &compileEnv};
+        const GLenum glShaderType = MG_Util::ConvertShaderStageToGLEnum(stage);
+        // Always 0 on both production parse paths; see the key inventory on
+        // ShaderParseVerdictKeyInputs for why it is in the key regardless.
+        constexpr Uint32 kShaderCompileFlags = 0;
 
-        auto result = ShaderCompiler::CompileShader(attrib);
-        if (result) {
+        // ---- L1c of the shader translation memo: the PARSE VERDICT ----------------------
+        // Everything below this probe - the glslang parse itself - is what a hit skips. What
+        // a hit does NOT produce is a TShader, and that is deliberate rather than a
+        // limitation: the TShader is consume-once, so it could never have been shared, and
+        // nothing on the COMPILE side of GL reads it. GL_COMPILE_STATUS, the info log,
+        // GL_SHADER_SOURCE, attach/detach and reuse across programs are all answered from
+        // what the verdict and the source-only half already carry.
+        //
+        // The parse is not skipped, it is DEFERRED: ClaimParsedShader re-parses on demand
+        // when a link finds no stored parse. A link that hits L1 never asks, so the parse
+        // never happens at all; a link that misses pays exactly one parse, where the CAS
+        // loser has always paid it. See TranslationCache.h's L1c section.
+        const TranslationCacheKey parseKey =
+            ShaderTranslationCacheEnabled()
+                ? BuildShaderParseVerdictKey(ShaderParseVerdictKeyInputs{
+                      .frontendFingerprint = compileEnv.frontendFingerprint,
+                      .shaderType = glShaderType,
+                      .preprocessedSource = StringView(shared.preprocessedSource),
+                      .shaderCompileFlags = kShaderCompileFlags})
+                : TranslationCacheKey{};
+        const ShaderParseVerdictPtr verdict =
+            parseKey.Valid() ? GetShaderParseVerdictCache().Find(parseKey) : nullptr;
+
+        // The two branches produce exactly one thing between them - a verdict, plus a TShader
+        // only when this task actually parsed - and converge on one publish below. Keeping the
+        // publish common is what stops a hit and a miss from ever drifting on WHAT a compile
+        // makes observable.
+        Bool parsedOk = false;
+        String parseLog;
+        SharedPtr<glslang::TShader> parsedShader;
+
+        if (verdict) {
+            parsedOk = verdict->parsed;
+            parseLog = verdict->infoLog;
+            MGLOG_D("ShaderCompileTask: shader %u (stage %d) L1c hit - the glslang parse was skipped; "
+                    "compileStatus = %d",
+                    externalIndex, static_cast<Int>(stage), static_cast<Int>(parsedOk));
+        } else {
+            const ShaderAttrib attrib{.shaderType = glShaderType,
+                                      .sourceStr = shared.preprocessedSource,
+                                      .flags = kShaderCompileFlags,
+                                      .env = &compileEnv};
+            auto result = ShaderCompiler::CompileShader(attrib);
+            parsedOk = result.has_value();
+            if (parsedOk) {
+                parsedShader = result.value();
+            } else {
+                parseLog = result.error().log;
+            }
+            if (parseKey.Valid()) {
+                auto freshVerdict = MakeShared<ShaderParseVerdict>();
+                freshVerdict->parsed = parsedOk;
+                // Empty on success by construction, matching what the publish below does with
+                // the artifacts' own log; the diagnostic the application reads on failure.
+                freshVerdict->infoLog = parseLog;
+                const SizeT verdictBytes = ShaderParseVerdictBytes(*freshVerdict);
+                GetShaderParseVerdictCache().Insert(parseKey, ShaderParseVerdictPtr(Move(freshVerdict)),
+                                                    verdictBytes);
+            }
+        }
+
+        if (parsedOk) {
             artifacts.compileStatus = true;
-            artifacts.shader = result.value();
+            // NULL ON AN L1c HIT, and that is a supported state rather than an oversight: see
+            // ShaderCompileArtifacts::shader and ClaimParsedShader.
+            artifacts.shader = Move(parsedShader);
             // Copy, not move: `shared` may alias a cache entry that has to outlive us, and
-            // `fresh` is about to be handed to the cache.
+            // `fresh` is about to be handed to the cache. Populated on the hit path too - it
+            // is what ClaimParsedShader's deferred parse consumes.
             artifacts.preprocessedSource = shared.preprocessedSource;
             artifacts.explicitUniformLocations = shared.explicitUniformLocations;
             artifacts.explicitOpaqueBindings = shared.explicitOpaqueBindings;
@@ -267,7 +353,7 @@ namespace MobileGL::MG_State::GLState {
                 cache->Insert(stage, sourceHash, *source, compileEnv.fingerprint, Move(fresh));
             }
         } else {
-            artifacts.infoLog = result.error().log;
+            artifacts.infoLog = Move(parseLog);
             // Deferred, not logged here, for two reasons. MGLOG from a pool thread interleaves
             // mid-line with the GL thread's own output and lands out of order relative to the
             // glCompileShader that caused it; diagnostics.logLines is replayed by the join, on
@@ -310,10 +396,11 @@ namespace MobileGL::MG_State::GLState {
             }
         }
 
-        // Either another link already consumed the stored parse (and mapIO mutated its
-        // intermediate), or there never was one. Re-parse the preprocessed source through the
-        // identical configuration; that costs one glslang parse, which is what GenerateBinary
-        // used to spend here on EVERY link rather than only on reuse.
+        // Three ways to be here: another link already consumed the stored parse (and mapIO
+        // mutated its intermediate); the compile hit L1c and never parsed at all; or there
+        // simply never was one. All three want the same thing - parse the preprocessed source
+        // through the identical configuration. That costs one glslang parse, which is what
+        // GenerateBinary used to spend here on EVERY link rather than only when needed.
         //
         // The guard is not optional on this path: from stage 4 this runs on a pool worker,
         // and TShader::parse would leave that worker's TLS allocator pointing at a pool the
@@ -329,7 +416,12 @@ namespace MobileGL::MG_State::GLState {
                             .env = artifacts.env.get()};
         auto result = ShaderCompiler::CompileShader(attrib);
         if (!result) {
-            // Should be unreachable: the same source parsed successfully at Compile().
+            // Should be unreachable. This exact (stage, preprocessed source, front-end env)
+            // parsed successfully once - either at this node's own Compile(), or at the
+            // Compile() whose verdict L1c handed this node - and every input the parse reads
+            // is covered by that tuple. ConsumeShaders turns a null into a failed link with a
+            // named internal error rather than a crash, which is the right shape for a
+            // "cannot happen" that would otherwise be a silent miscompile.
             outReparseLog = result.error().log;
             return nullptr;
         }

MobileGL/MG_State/GLState/ProgramState/ShaderCompileTask.h

@@ -41,6 +41,20 @@ namespace MobileGL::MG_State::GLState {
         // re-parse in ClaimParsedShader() reproduces the original parse exactly, instead of
         // re-reading whatever the backend says now.
         SharedPtr<const MG_Util::ShaderTranspiler::CompileEnv> env;
+        // The parse, WHEN THIS COMPILE ACTUALLY PARSED - and null otherwise, including when
+        // compileStatus is true.
+        //
+        // That combination is not a half-finished compile; it is an L1c hit. The translation
+        // memo's compile half (TranslationCache.h) knows this exact (stage, preprocessed
+        // source, front-end env) parses cleanly, so the verdict is published without running
+        // glslang. What a hit cannot hand over is the TShader itself: mapIO mutates its
+        // aliased intermediate at link, so a parse feeds exactly ONE link and could never
+        // have been shared between compiles.
+        //
+        // Nothing on the compile side of GL reads this - GL_COMPILE_STATUS, the info log,
+        // GL_SHADER_SOURCE, attach/detach and reuse across programs are all answered from the
+        // fields below. The one reader is ClaimParsedShader, which treats null as "parse it
+        // now", which is the same path the consume-once CAS loser has always taken.
         SharedPtr<glslang::TShader> shader;
         // The source the parse actually consumed (after PreprocessShaderSource), kept for
         // ClaimParsedShader's re-parse so a later link never depends on the preprocessor
@@ -53,8 +67,9 @@ namespace MobileGL::MG_State::GLState {
     };
 
     // The unit of asynchronous shader compilation: one glCompileShader's worth of pure CPU
-    // work - preprocess, the two lexical rejections, the two lexical extractions, and the
-    // glslang parse - with every input it needs owned by the node itself.
+    // work - preprocess, the two lexical rejections, the two lexical extractions, and (unless
+    // the translation memo's compile half already knows the answer) the glslang parse - with
+    // every input it needs owned by the node itself.
     //
     // That ownership is the whole point. The node reads no GL-thread state (the source is a
     // SharedPtr<const String> snapshot, the device limits come from the CompileEnv snapshot,
@@ -87,22 +102,29 @@ namespace MobileGL::MG_State::GLState {
         // ---- output: valid iff IsComplete(), immutable afterwards ----
         ShaderCompileArtifacts artifacts;
 
-        // Hands out a link-consumable TShader, exactly once for the stored parse.
+        // Hands out a link-consumable TShader, parsing one on demand when this node has none.
         //
-        // glslang's mapIO mutates the TShader's aliased intermediate, so the parse this node
-        // produced may feed exactly ONE link; every later link (a relink, or the same shader
-        // attached to a second program) needs a fresh parse. The claim is a CAS on this
-        // shared node rather than a flag on the ShaderObject because from stage 4 the two
-        // callers can be two ProgramLinkTasks running on two workers: two programs sharing
-        // one shader, linked back to back. Copying the parse out and tracking consumed-ness
-        // per program would let both of them decide they were the first, run mapIO over the
-        // same intermediate twice, and ship silently corrupt SPIR-V.
+        // TWO WAYS TO GET HERE WITHOUT A STORED PARSE, and they share one implementation:
+        //   * the CAS loser. glslang's mapIO mutates the TShader's aliased intermediate, so
+        //     the parse this node produced may feed exactly ONE link; every later link (a
+        //     relink, or the same shader attached to a second program) needs a fresh one. The
+        //     claim is a CAS on this shared node rather than a flag on the ShaderObject
+        //     because from stage 4 the two callers can be two ProgramLinkTasks on two
+        //     workers: two programs sharing one shader, linked back to back. Copying the
+        //     parse out and tracking consumed-ness per program would let both of them decide
+        //     they were the first, run mapIO over the same intermediate twice, and ship
+        //     silently corrupt SPIR-V.
+        //   * an L1c HIT. The compile published a verdict without parsing at all (see
+        //     ShaderCompileArtifacts::shader), so this call IS the parse - deferred out of
+        //     glCompileShader to the first link that genuinely needs an AST. A link served
+        //     from L1 never gets here, which is the whole point: that program's front end
+        //     never constructs a glslang object of any kind.
         //
-        // The CAS loser re-parses artifacts.preprocessedSource against THIS node's own
+        // Either way the parse runs over artifacts.preprocessedSource against THIS node's own
         // CompileEnv (not against whatever the backend reports now), through the identical
-        // CompileShader path - so winner and loser produce byte-identical SPIR-V. Callable
-        // only once IsComplete() and compileStatus are true. Returns null only if that
-        // re-parse fails, and outReparseLog then carries its diagnostics.
+        // CompileShader path - so every claimant produces byte-identical SPIR-V. Callable
+        // only once IsComplete() and compileStatus are true. Returns null only if that parse
+        // fails, and outReparseLog then carries its diagnostics.
         //
         // Const because the claim is the node's own synchronization, not a mutation of its
         // published artifacts: a claim that is taken and then abandoned (its link was

MobileGL/MG_State/GLState/ProgramState/ShaderPreprocessCache.h

@@ -26,6 +26,9 @@ namespace MobileGL::MG_State::GLState {
         ComputeLocalSizeRejected,
         // FindReservedIdentifierViolation rejected it.
         ReservedIdentifierRejected,
+        // FindShaderStorageBindingViolation rejected it: a storage block declared a binding at or
+        // past GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS.
+        ResourceBindingRejected,
         // The source-only half was clean but glslang rejected the preprocessed source.
         // Memoizing this saves the parse itself on every later object with that source.
         ParseFailed,

MobileGL/MG_State/GLState/TextureState/MipmapStorage.cpp

@@ -48,6 +48,7 @@ namespace MobileGL {
                     m_dirtyRects.resize(requiredLevelCount);
                     m_compressedData.resize(requiredLevelCount);
                     m_compressedFormats.resize(requiredLevelCount, GL_NONE);
+                    m_requestedCompressedFormats.resize(requiredLevelCount, GL_NONE);
                 }
 
                 m_texelSizes[level] = input.texelSize;
@@ -79,6 +80,9 @@ namespace MobileGL {
                 m_compressedFormats[level] = GL_NONE;
                 m_compressedData[level].clear();
                 m_compressedData[level].shrink_to_fit();
+                // Same story for the requested-format tag: a respecified level is whatever this
+                // call asked for, and the compressed entry points re-arm it right afterwards.
+                m_requestedCompressedFormats[level] = GL_NONE;
             }
 
             void MipmapStorage::SetCompressedImage(Uint level, GLenum internalFormat, const void* data, SizeT size) {
@@ -110,6 +114,16 @@ namespace MobileGL {
                 return m_compressedData[level].data();
             }
 
+            void MipmapStorage::SetRequestedCompressedFormat(Uint level, GLenum internalFormat) {
+                if (level >= m_requestedCompressedFormats.size()) return;
+                m_requestedCompressedFormats[level] = internalFormat;
+            }
+
+            GLenum MipmapStorage::GetRequestedCompressedFormat(Uint level) const {
+                if (level >= m_requestedCompressedFormats.size()) return GL_NONE;
+                return m_requestedCompressedFormats[level];
+            }
+
             void MipmapStorage::TruncateToLevelCount(SizeT levelCount) {
                 if (levelCount >= m_data.size()) return;
 
@@ -120,6 +134,7 @@ namespace MobileGL {
                 m_dirtyRects.resize(levelCount);
                 m_compressedData.resize(levelCount);
                 m_compressedFormats.resize(levelCount);
+                m_requestedCompressedFormats.resize(levelCount);
             }
 
             void MipmapStorage::UpdateSubData(Uint level, DataPtr input) {

MobileGL/MG_State/GLState/TextureState/MipmapStorage.h

@@ -96,6 +96,18 @@ namespace MobileGL {
                 SizeT GetCompressedByteSize(Uint level) const;
                 const void* MapCompressedData(Uint level) const;
 
+                // The compressed internalformat the application ASKED for, which is not the same
+                // question as the one above: the six generic GL_COMPRESSED_* enums let the
+                // implementation choose, MobileGL chooses uncompressed storage, and the level is
+                // deliberately left untagged so GL_TEXTURE_COMPRESSED keeps answering false and
+                // glGetCompressedTexImage is not handed a blob nothing ever compressed. The entry
+                // points that must refuse a compressed image outright (glClearTexImage /
+                // glClearTexSubImage, GL 4.6 core 8.19) still need to know, so the request is
+                // recorded separately. Set right after AllocateLevel, which clears it.
+                void SetRequestedCompressedFormat(Uint level, GLenum internalFormat);
+                // GL_NONE when the level was not requested with a compressed internalformat.
+                GLenum GetRequestedCompressedFormat(Uint level) const;
+
             protected:
                 // Insert one clamped, non-empty write box, keeping the list disjoint
                 // and bounded (see kMaxDirtyRects).
@@ -115,6 +127,7 @@ namespace MobileGL {
                 Vector<Vector<MipmapDirtyRegion>> m_dirtyRects;
                 Vector<Vector<Uint8>> m_compressedData;
                 Vector<GLenum> m_compressedFormats;
+                Vector<GLenum> m_requestedCompressedFormats;
             };
         } // namespace GLState
     } // namespace MG_State

MobileGL/MG_State/GLState/TextureState/MipmapUploadTargetArray.h

@@ -111,6 +111,16 @@ namespace MobileGL {
                     return m_storage[targetIndex].MapCompressedData(level);
                 }
 
+                void SetRequestedCompressedFormat(Uint targetIndex, Uint level, GLenum internalFormat) {
+                    MOBILEGL_ASSERT(targetIndex < TargetCount, "SetRequestedCompressedFormat: target invalid");
+                    m_storage[targetIndex].SetRequestedCompressedFormat(level, internalFormat);
+                }
+
+                GLenum GetRequestedCompressedFormat(Uint targetIndex, Uint level) const {
+                    MOBILEGL_ASSERT(targetIndex < TargetCount, "GetRequestedCompressedFormat: target invalid");
+                    return m_storage[targetIndex].GetRequestedCompressedFormat(level);
+                }
+
             protected:
                 Array<MipmapStorage, TargetCount> m_storage;
             };

MobileGL/MG_State/GLState/TextureState/TextureObject.cpp

@@ -250,6 +250,10 @@ namespace MobileGL {
                 return m_contentVersion;
             }
 
+            Uint64 TextureObjectBase::GetShapeVersion() const {
+                return m_shapeVersion;
+            }
+
             Bool TextureObjectBase::IsMipmapCompleteForFilterCached(Bool mipmapped) const {
                 const int slot = mipmapped ? 1 : 0;
                 if (m_completeMemoShapeVersion[slot] == m_shapeVersion) {
@@ -373,6 +377,18 @@ namespace MobileGL {
                 return m_textureStorage.MapCompressedData(GetIndexOfTextureUploadTarget(uploadTarget), mipmapLevel);
             }
 
+            void TextureObjectWithOneMipmap::SetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget,
+                                                                       Uint mipmapLevel, GLenum internalFormat) {
+                m_textureStorage.SetRequestedCompressedFormat(GetIndexOfTextureUploadTarget(uploadTarget), mipmapLevel,
+                                                              internalFormat);
+            }
+
+            GLenum TextureObjectWithOneMipmap::GetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget,
+                                                                       Uint mipmapLevel) const {
+                return m_textureStorage.GetRequestedCompressedFormat(GetIndexOfTextureUploadTarget(uploadTarget),
+                                                                     mipmapLevel);
+            }
+
             IntVec3 TextureObjectWithOneMipmap::GetBaseSize() const {
                 if (m_textureStorage.GetLevelCount() == 0) {
                     return {0, 0, 0};

MobileGL/MG_State/GLState/TextureState/TextureObject.h

@@ -55,6 +55,12 @@ namespace MobileGL::MG_State::GLState {
         // Backends compare it against a per-resource snapshot to skip re-syncing unchanged
         // textures across draws (e.g. the block atlas bound across a whole terrain batch).
         virtual Uint64 GetContentVersion() const = 0;
+        // Monotonic counter bumped on every SHAPE mutation - level sizes, the stored level
+        // set, the internal format, the level range (see BumpShapeVersion). Disjoint from the
+        // content version on purpose: glTexImage2D(..., nullptr) re-specifies a level's size
+        // without dirtying a single texel, so a backend that keys its "nothing changed since
+        // the last sync" skip on content alone keeps a resource of the OLD size alive.
+        virtual Uint64 GetShapeVersion() const = 0;
         // Answers IsMipmapCompleteForFilter() from a memo. Sampling completeness is a
         // property of the texture's SHAPE - level sizes, level count, level range,
         // internal format - and never of its texel content, but every draw asks about
@@ -106,6 +112,7 @@ namespace MobileGL::MG_State::GLState {
         void SetImmutableLevels(Uint levels) override;
         Uint16 GetTextureParamsVersion() const override;
         Uint64 GetContentVersion() const override;
+        Uint64 GetShapeVersion() const override;
         Bool IsMipmapCompleteForFilterCached(Bool mipmapped) const override;
         // Bumps the content version without touching per-level storage-dirty flags. Used when the
         // set of defined mip levels grows via GPU-side mip generation (glGenerateMipmap): the level
@@ -220,6 +227,15 @@ namespace MobileGL::MG_State::GLState {
         virtual GLenum GetMipmapCompressedFormat(TextureUploadTarget uploadTarget, Uint mipmapLevel) const = 0;
         virtual SizeT GetMipmapCompressedByteSize(TextureUploadTarget uploadTarget, Uint mipmapLevel) const = 0;
         virtual const void* MapMipmapCompressedImage(TextureUploadTarget uploadTarget, Uint mipmapLevel) const = 0;
+
+        // The compressed internalformat the level was REQUESTED with, recorded even when MobileGL
+        // answered it with uncompressed storage (the six generic GL_COMPRESSED_* enums) - see
+        // MipmapStorage. Only the entry points GL forbids on a compressed image read it.
+        virtual void SetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget, Uint mipmapLevel,
+                                                        GLenum internalFormat) = 0;
+        // GL_NONE when the level was not requested with a compressed internalformat.
+        virtual GLenum GetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget,
+                                                          Uint mipmapLevel) const = 0;
     };
 
     // Cheap replacement for dynamic_cast on the hot path: TextureObjectMipmap is the
@@ -286,6 +302,9 @@ namespace MobileGL::MG_State::GLState {
         GLenum GetMipmapCompressedFormat(TextureUploadTarget uploadTarget, Uint mipmapLevel) const override;
         SizeT GetMipmapCompressedByteSize(TextureUploadTarget uploadTarget, Uint mipmapLevel) const override;
         const void* MapMipmapCompressedImage(TextureUploadTarget uploadTarget, Uint mipmapLevel) const override;
+        void SetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget, Uint mipmapLevel,
+                                                GLenum internalFormat) override;
+        GLenum GetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget, Uint mipmapLevel) const override;
 
         IntVec3 GetBaseSize() const override;
         Bool IsComplete() const override;

MobileGL/MG_State/GLState/TextureState/TextureObject2DCube.cpp

@@ -96,6 +96,18 @@ namespace MobileGL {
                 return m_textureStorage.MapCompressedData(GetIndexOfTextureUploadTarget(uploadTarget), mipmapLevel);
             }
 
+            void TextureObject2DCube::SetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget,
+                                                                       Uint mipmapLevel, GLenum internalFormat) {
+                m_textureStorage.SetRequestedCompressedFormat(GetIndexOfTextureUploadTarget(uploadTarget), mipmapLevel,
+                                                              internalFormat);
+            }
+
+            GLenum TextureObject2DCube::GetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget,
+                                                                           Uint mipmapLevel) const {
+                return m_textureStorage.GetRequestedCompressedFormat(GetIndexOfTextureUploadTarget(uploadTarget),
+                                                                     mipmapLevel);
+            }
+
             Uint TextureObject2DCube::GetIndexOfTextureUploadTarget(TextureUploadTarget target) const {
                 MOBILEGL_ASSERT(TextureUploadTarget::CubeMapPositiveX <= target &&
                                     target <= TextureUploadTarget::CubeMapNegativeZ,

MobileGL/MG_State/GLState/TextureState/TextureObject2DCube.h

@@ -39,6 +39,10 @@ namespace MobileGL {
                 SizeT GetMipmapCompressedByteSize(TextureUploadTarget uploadTarget, Uint mipmapLevel) const override;
                 const void* MapMipmapCompressedImage(TextureUploadTarget uploadTarget,
                                                      Uint mipmapLevel) const override;
+                void SetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget, Uint mipmapLevel,
+                                                        GLenum internalFormat) override;
+                GLenum GetMipmapRequestedCompressedFormat(TextureUploadTarget uploadTarget,
+                                                          Uint mipmapLevel) const override;
 
                 IntVec3 GetBaseSize() const override;
                 Bool IsComplete() const override;

MobileGL/MG_Test/Backend/DirectGLES/BaseInstanceInjectionTest.cpp

@@ -0,0 +1,167 @@
+// MobileGL - MobileGL/MG_Test/Backend/DirectGLES/BaseInstanceInjectionTest.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// The gate on the gl_BaseInstance indirect lowering in
+// MG_Backend/DirectGLES/Managers.cpp. That lowering declares a std430 storage block in the
+// VERTEX stage, and a vertex-stage storage block is optional in both APIs: the minimum for
+// GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS is 0 (GL 4.6 table 23.64, ES 3.2 table 21.44), and ARM's
+// GLES driver takes that allowance - a Mali-G925-Immortalis reports 0 for it and for all three
+// other graphics stages.
+//
+// Emitting the block on such a driver does not make it work. The driver refuses the program at
+// link time ("The number of vertex shader storage blocks (1) is greater than the maximum number
+// allowed (0)"), and because MobileGL's frontend GL_LINK_STATUS is glslang's rather than the
+// driver's, the application is told the program linked and then every draw with it renders
+// nothing. Dropping the indirect half instead keeps ordinary draws working and costs only the
+// per-command baseInstance of an indirect draw.
+//
+// No GL context and no driver: the lowering is a pure String -> String pass over one capability.
+
+#include <gtest/gtest.h>
+
+#include <MG_Backend/DirectGLES/DirectGLES.h>
+#include <MG_Backend/DirectGLES/Managers.h>
+
+using MobileGL::Bool;
+using MobileGL::String;
+using MobileGL::MG_Backend::DirectGLES::g_GLESCapabilities;
+using MobileGL::MG_Backend::DirectGLES::PromoteDrawParameterGlobalsToUniforms;
+using MobileGL::MG_Backend::DirectGLES::VertexStageStorageBlockUsable;
+
+namespace {
+    // The capability block is a process-global the backend fills in at init; restore whatever
+    // was there so ordering between this suite and any other that touches it cannot matter.
+    struct ScopedGLESCapabilitiesOverride {
+        ScopedGLESCapabilitiesOverride(): saved(g_GLESCapabilities) {}
+        ~ScopedGLESCapabilitiesOverride() { g_GLESCapabilities = saved; }
+        ScopedGLESCapabilitiesOverride(const ScopedGLESCapabilitiesOverride&) = delete;
+        ScopedGLESCapabilitiesOverride& operator=(const ScopedGLESCapabilitiesOverride&) = delete;
+
+        MobileGL::MG_External::GLESCapabilities saved;
+    };
+
+    Bool Contains(const String& haystack, const String& needle) {
+        return haystack.find(needle) != String::npos;
+    }
+
+    // What SPIRV-Cross hands the backend after LowerDrawParametersPass has demoted
+    // gl_BaseInstance to a Private global.
+    constexpr const char* kLoweredBaseInstanceVertexShader = R"(#version 310 es
+highp int mg_BaseInstanceLowered;
+void main() {
+    int instance = gl_InstanceID + mg_BaseInstanceLowered;
+    gl_Position = vec4(float(instance));
+}
+)";
+} // namespace
+
+// One block is all the indirect view needs, so the predicate is a >= 1 test.
+TEST(VertexStageStorageBlockUsableTest, RequiresAtLeastOneBlock) {
+    EXPECT_FALSE(VertexStageStorageBlockUsable(0));
+    EXPECT_TRUE(VertexStageStorageBlockUsable(1));
+    EXPECT_TRUE(VertexStageStorageBlockUsable(16));
+}
+
+// A driver that leaves the out-param untouched tells us nothing, and guessing "yes" is exactly
+// what produces the unlinkable program. Unusable, not clamped up to one.
+TEST(VertexStageStorageBlockUsableTest, ANegativeCountIsUnusableRatherThanClamped) {
+    EXPECT_FALSE(VertexStageStorageBlockUsable(-1));
+    EXPECT_FALSE(VertexStageStorageBlockUsable(-2147483647 - 1));
+}
+
+TEST(BaseInstanceInjectionGate, DriverWithVertexStorageBlocksGetsTheIndirectView) {
+    const ScopedGLESCapabilitiesOverride capsGuard;
+    g_GLESCapabilities.IndirectDrawInstanceIdIncludesBaseInstance = false;
+    g_GLESCapabilities.MaxShaderStorageBufferBindings = 13;
+    g_GLESCapabilities.MaxVertexShaderStorageBlocks = 1;
+
+    const String rewritten =
+        PromoteDrawParameterGlobalsToUniforms(kLoweredBaseInstanceVertexShader, GL_VERTEX_SHADER);
+
+    EXPECT_TRUE(Contains(rewritten, "layout(std430, binding = 12) readonly buffer mg_IndirectParams"));
+    EXPECT_TRUE(Contains(rewritten, "uniform highp int mg_BaseInstanceWordIndex;"));
+    EXPECT_TRUE(Contains(rewritten, "#define mg_BaseInstanceLowered ((mg_BaseInstanceWordIndex > 0) ? "
+                                    "int(mg_indirectWords[uint(mg_BaseInstanceWordIndex - 1)]) : mg_BaseInstance)"))
+        << rewritten;
+}
+
+// The bug this gate exists for. The block must not appear at all - not at a different binding,
+// not behind a preprocessor guard: a declaration the driver counts is a declaration that makes
+// the whole program unlinkable, and the frontend never surfaces that failure.
+TEST(BaseInstanceInjectionGate, DriverWithoutVertexStorageBlocksDeclaresNoBlockAtAll) {
+    const ScopedGLESCapabilitiesOverride capsGuard;
+    g_GLESCapabilities.IndirectDrawInstanceIdIncludesBaseInstance = false;
+    g_GLESCapabilities.MaxShaderStorageBufferBindings = 13;
+    g_GLESCapabilities.MaxVertexShaderStorageBlocks = 0;
+
+    const String rewritten =
+        PromoteDrawParameterGlobalsToUniforms(kLoweredBaseInstanceVertexShader, GL_VERTEX_SHADER);
+
+    EXPECT_FALSE(Contains(rewritten, "mg_IndirectParams")) << rewritten;
+    EXPECT_FALSE(Contains(rewritten, "buffer"));
+    EXPECT_FALSE(Contains(rewritten, "mg_indirectWords"));
+    // Nothing reads the word index any more, so nothing may declare it either - its presence is
+    // what BackendProgramObjectImpl uses to decide whether to bind an indirect params buffer.
+    EXPECT_FALSE(Contains(rewritten, "mg_BaseInstanceWordIndex"));
+}
+
+// Degraded, but still correct for every non-indirect draw: the plain mg_BaseInstance uniform is
+// what the non-indirect draw entry points already write.
+TEST(BaseInstanceInjectionGate, WithoutTheBlockBaseInstanceFallsBackToThePlainUniform) {
+    const ScopedGLESCapabilitiesOverride capsGuard;
+    g_GLESCapabilities.IndirectDrawInstanceIdIncludesBaseInstance = false;
+    g_GLESCapabilities.MaxShaderStorageBufferBindings = 13;
+    g_GLESCapabilities.MaxVertexShaderStorageBlocks = 0;
+
+    const String rewritten =
+        PromoteDrawParameterGlobalsToUniforms(kLoweredBaseInstanceVertexShader, GL_VERTEX_SHADER);
+
+    EXPECT_TRUE(Contains(rewritten, "uniform highp int mg_BaseInstance;")) << rewritten;
+    EXPECT_TRUE(Contains(rewritten, "#define mg_BaseInstanceLowered (mg_BaseInstance)")) << rewritten;
+    // The global declaration must be gone; leaving it would shadow the define.
+    EXPECT_FALSE(Contains(rewritten, "highp int mg_BaseInstanceLowered;\n"));
+}
+
+// On a driver that both leaks baseInstance into gl_InstanceID and has no vertex storage block,
+// the rebase has nothing to subtract. Subtracting the uniform instead would remove the base
+// twice from every non-indirect draw, which is worse than not rebasing at all.
+TEST(BaseInstanceInjectionGate, WithoutTheBlockInstanceIdRebaseCollapsesToIdentity) {
+    const ScopedGLESCapabilitiesOverride capsGuard;
+    g_GLESCapabilities.IndirectDrawInstanceIdIncludesBaseInstance = true;
+    g_GLESCapabilities.MaxShaderStorageBufferBindings = 13;
+    g_GLESCapabilities.MaxVertexShaderStorageBlocks = 0;
+
+    const String rewritten =
+        PromoteDrawParameterGlobalsToUniforms(kLoweredBaseInstanceVertexShader, GL_VERTEX_SHADER);
+
+    EXPECT_TRUE(Contains(rewritten, "#define mg_ZeroBasedInstanceID gl_InstanceID")) << rewritten;
+    EXPECT_FALSE(Contains(rewritten, "gl_InstanceID - ("));
+    EXPECT_FALSE(Contains(rewritten, "mg_indirectWords"));
+}
+
+// The gate is scoped to the block, not to the whole pass: mg_DrawID and mg_BaseVertex are plain
+// uniforms with no storage block behind them and must still be promoted on such a driver.
+TEST(BaseInstanceInjectionGate, DrawIdAndBaseVertexArePromotedRegardless) {
+    const ScopedGLESCapabilitiesOverride capsGuard;
+    g_GLESCapabilities.IndirectDrawInstanceIdIncludesBaseInstance = false;
+    g_GLESCapabilities.MaxShaderStorageBufferBindings = 13;
+    g_GLESCapabilities.MaxVertexShaderStorageBlocks = 0;
+
+    const String source = R"(#version 310 es
+highp int mg_DrawID;
+highp int mg_BaseVertex;
+void main() {
+    gl_Position = vec4(float(mg_DrawID + mg_BaseVertex));
+}
+)";
+
+    const String rewritten = PromoteDrawParameterGlobalsToUniforms(source, GL_VERTEX_SHADER);
+
+    EXPECT_TRUE(Contains(rewritten, "uniform highp int mg_DrawID;")) << rewritten;
+    EXPECT_TRUE(Contains(rewritten, "uniform highp int mg_BaseVertex;")) << rewritten;
+}

MobileGL/MG_Test/Backend/DirectGLES/CMakeLists.txt

@@ -16,5 +16,22 @@ target_link_libraries(
         ${LINK_LIBRARIES}
 )
 
+add_executable(
+        BaseInstanceInjectionTest
+        BaseInstanceInjectionTest.cpp
+)
+
+target_include_directories(BaseInstanceInjectionTest PRIVATE
+        ${MGL_ROOT}/include
+        ${MGL_ROOT}/MobileGL
+)
+
+target_link_libraries(
+        BaseInstanceInjectionTest PRIVATE
+        GTest::gtest_main
+        ${LINK_LIBRARIES}
+)
+
 include(GoogleTest)
 gtest_discover_tests(EsslShaderPassTest DISCOVERY_TIMEOUT 30 PROPERTIES LABELS unit)
+gtest_discover_tests(BaseInstanceInjectionTest DISCOVERY_TIMEOUT 30 PROPERTIES LABELS unit)

MobileGL/MG_Test/Backend/DirectGLES/EsslShaderPassTest.cpp

@@ -21,6 +21,7 @@ using MobileGL::MG_Backend::DirectGLES::PrgramImpl::ForceFlatIntegerVaryings;
 using MobileGL::MG_Backend::DirectGLES::PrgramImpl::IMAGE_WRITE_ALIAS_PREFIX;
 using MobileGL::MG_Backend::DirectGLES::PrgramImpl::RemoveLayoutBinding;
 using MobileGL::MG_Backend::DirectGLES::PrgramImpl::RequestExtendedImageFormats;
+using MobileGL::MG_Backend::DirectGLES::PrgramImpl::RequestViewportArrayExtension;
 using MobileGL::MG_Backend::DirectGLES::PrgramImpl::SplitReadWriteImageUniforms;
 
 namespace {
@@ -58,9 +59,11 @@ void main()
     const String out = SplitReadWriteImageUniforms(source);
 
     // Both halves: same binding, same format, same type - which is what makes two image
-    // variables on one image unit legal.
-    EXPECT_TRUE(Contains(out, "layout(binding = 2, rgba8) uniform readonly highp image2D goku;"));
-    EXPECT_TRUE(Contains(out, "layout(binding = 2, rgba8) uniform writeonly highp image2D " + WriteAlias("goku") + ";"));
+    // variables on one image unit legal - and both `coherent`, which is what makes the store
+    // through one of them visible to the load through the other.
+    EXPECT_TRUE(Contains(out, "layout(binding = 2, rgba8) uniform coherent readonly highp image2D goku;"));
+    EXPECT_TRUE(Contains(
+        out, "layout(binding = 2, rgba8) uniform coherent writeonly highp image2D " + WriteAlias("goku") + ";"));
 
     // The load keeps the original name, the store moves to the writeonly half.
     EXPECT_TRUE(Contains(out, "imageLoad(goku,"));
@@ -151,9 +154,9 @@ void main()
 }
 )";
     const String out = SplitReadWriteImageUniforms(source);
-    EXPECT_TRUE(Contains(out, "layout(binding = 6, rgba8) uniform readonly highp image2D gohan[3];"));
-    EXPECT_TRUE(Contains(out,
-                         "layout(binding = 6, rgba8) uniform writeonly highp image2D " + WriteAlias("gohan") + "[3];"));
+    EXPECT_TRUE(Contains(out, "layout(binding = 6, rgba8) uniform coherent readonly highp image2D gohan[3];"));
+    EXPECT_TRUE(Contains(
+        out, "layout(binding = 6, rgba8) uniform coherent writeonly highp image2D " + WriteAlias("gohan") + "[3];"));
     EXPECT_TRUE(Contains(out, "imageStore(" + WriteAlias("gohan") + "[1],"));
     EXPECT_TRUE(Contains(out, "imageLoad(gohan[2],"));
 }
@@ -173,9 +176,11 @@ void main()
 )";
     const String out = SplitReadWriteImageUniforms(source);
 
-    // goku is read+write -> split; goku_hd is write-only -> qualified in place, not split.
-    EXPECT_TRUE(Contains(out, "layout(binding = 1, rgba8) uniform readonly highp image2D goku;"));
-    EXPECT_TRUE(Contains(out, "layout(binding = 1, rgba8) uniform writeonly highp image2D " + WriteAlias("goku") + ";"));
+    // goku is read+write -> split (and coherent with it); goku_hd is write-only -> qualified in
+    // place, not split, and left non-coherent because nothing aliases it.
+    EXPECT_TRUE(Contains(out, "layout(binding = 1, rgba8) uniform coherent readonly highp image2D goku;"));
+    EXPECT_TRUE(Contains(
+        out, "layout(binding = 1, rgba8) uniform coherent writeonly highp image2D " + WriteAlias("goku") + ";"));
     EXPECT_TRUE(Contains(out, "layout(binding = 2, rgba8) uniform writeonly highp image2D goku_hd;"));
     EXPECT_TRUE(Contains(out, "imageStore(goku_hd,"));
     EXPECT_FALSE(Contains(out, WriteAlias("goku") + "_hd"));
@@ -196,6 +201,36 @@ void main()
     EXPECT_TRUE(Contains(out, "uniform readonly coherent restrict highp image2D goku;"));
     EXPECT_TRUE(
         Contains(out, "uniform writeonly coherent restrict highp image2D " + WriteAlias("goku") + ";"));
+    // ...and the coherent the split adds is not a SECOND one: a repeated memory qualifier is a
+    // compile error in ESSL, so the source's own has to be recognized.
+    EXPECT_EQ(CountOf(out, "coherent"), 2u);
+}
+
+// The visibility half of the split, and the reason it is not cosmetic: GLSL orders a
+// same-variable read-after-write within one invocation by construction, but once the store goes
+// through `mg_imageWrite_goku` and the load through `goku` the two are DIFFERENT variables, and
+// the ordering only holds if both are coherent. Desktop sources almost never say so - they had
+// no reason to - which is how KHR-GL4x.shader_image_load_store.advanced-memory-order's
+// store/load/compare loop started reading back the value it had not stored yet.
+TEST(SplitReadWriteImageUniformsTest, SplitPairIsMadeCoherentEvenWhenTheSourceIsNot) {
+    const String source = R"(#version 320 es
+layout(binding = 2, rgba8) uniform highp image2D goku;
+layout(binding = 3, rgba8) uniform highp image2D storeOnly;
+layout(location = 0) out highp vec4 mg_FragColor;
+void main()
+{
+    imageStore(goku, ivec2(0), vec4(1.0));
+    mg_FragColor = imageLoad(goku, ivec2(0));
+    imageStore(storeOnly, ivec2(0), vec4(2.0));
+}
+)";
+    const String out = SplitReadWriteImageUniforms(source);
+    EXPECT_TRUE(Contains(out, "uniform coherent readonly highp image2D goku;")) << out;
+    EXPECT_TRUE(Contains(out, "uniform coherent writeonly highp image2D " + WriteAlias("goku") + ";")) << out;
+    // Exactly the two halves of the pair, and nothing else: the store-only image is repaired in
+    // place, has no alias to stay visible to, and must not pay for uncached access.
+    EXPECT_EQ(CountOf(out, "coherent"), 2u);
+    EXPECT_TRUE(Contains(out, "uniform writeonly highp image2D storeOnly;")) << out;
 }
 
 // imageSize reads no texels and writes none, so it decides nothing; readonly is what keeps
@@ -550,3 +585,55 @@ void main() { imageStore(uni_image, ivec2(0), uvec4(1u)); }
     EXPECT_EQ(out, source);
     EXPECT_EQ(CountOf(out, "GL_NV_image_formats"), 1u) << out;
 }
+
+// --- GL_OES_viewport_array directive -------------------------------------------------------------
+
+// SPIRV-Cross prints gl_ViewportIndex bare and requests nothing for it, and ESSL has no core
+// spelling at any version - so without this directive the stage fails to compile, the program is
+// marked unusable and every draw made with it silently renders nothing.
+TEST(RequestViewportArrayExtensionTest, TheDirectiveGoesRightAfterTheVersionLine) {
+    const String source = R"(#version 320 es
+layout(points) in;
+layout(points, max_vertices = 1) out;
+void main() { gl_ViewportIndex = gl_InvocationID; EmitVertex(); }
+)";
+    const String out = RequestViewportArrayExtension(source, true);
+    EXPECT_TRUE(Contains(out, "#version 320 es\n#extension GL_OES_viewport_array : require\n")) << out;
+}
+
+// Never speculatively: ARM's compiler hard-errors on an `#extension` naming a string the driver
+// does not advertise, so the caller's "not needed" answer has to be honoured exactly. A driver
+// without the extension gets the LowerViewportIndexPass fallback instead.
+TEST(RequestViewportArrayExtensionTest, NotNeededMeansNotEmitted) {
+    const String source = R"(#version 320 es
+layout(points) in;
+layout(points, max_vertices = 1) out;
+void main() { gl_ViewportIndex = gl_InvocationID; EmitVertex(); }
+)";
+    EXPECT_EQ(RequestViewportArrayExtension(source, false), source);
+}
+
+TEST(RequestViewportArrayExtensionTest, AnAlreadyPresentDirectiveIsNotDuplicated) {
+    const String source = R"(#version 320 es
+#extension GL_OES_viewport_array : require
+layout(points) in;
+layout(points, max_vertices = 1) out;
+void main() { gl_ViewportIndex = gl_InvocationID; EmitVertex(); }
+)";
+    const String out = RequestViewportArrayExtension(source, true);
+    EXPECT_EQ(out, source);
+    EXPECT_EQ(CountOf(out, "GL_OES_viewport_array"), 1u) << out;
+}
+
+// The two image directives and this one share the insertion point, so a shader that needs both
+// must end up with both - and with #version still first.
+TEST(RequestViewportArrayExtensionTest, CoexistsWithTheImageFormatDirective) {
+    const String source = R"(#version 320 es
+layout(r8ui, binding = 1) uniform writeonly highp uimage2D uni_image;
+void main() { gl_ViewportIndex = 1; imageStore(uni_image, ivec2(0), uvec4(1u)); }
+)";
+    const String out = RequestViewportArrayExtension(RequestExtendedImageFormats(source, true), true);
+    EXPECT_EQ(out.find("#version 320 es"), 0u) << out;
+    EXPECT_TRUE(Contains(out, "#extension GL_NV_image_formats : require\n")) << out;
+    EXPECT_TRUE(Contains(out, "#extension GL_OES_viewport_array : require\n")) << out;
+}

MobileGL/MG_Test/BackendLoader/BackendLoaderTest.cpp

@@ -34,6 +34,42 @@ namespace {
         GLint maxFragmentImageUniforms = 4;
         GLint maxComputeImageUniforms = 5;
         bool maxGeometryImageUniformsQueried = false;
+        // Per-stage GL_MAX_*_SHADER_STORAGE_BLOCKS. The vertex and fragment pnames are ES 3.1,
+        // but the tessellation and geometry ones only exist from ES 3.2 on, so asking for them
+        // on an older context raises GL_INVALID_ENUM - the same shape as the buffer-texture and
+        // anisotropy probes. The "queried" flags are what pin that gating; the "raises error"
+        // knob is what pins the drain.
+        GLint maxTessControlSsboBlocks = 6;
+        GLint maxTessEvaluationSsboBlocks = 7;
+        GLint maxGeometrySsboBlocks = 8;
+        GLint maxFragmentSsboBlocks = 9;
+        bool tessAndGeometrySsboBlocksQueried = false;
+        bool perStageSsboBlockQueryRaisesError = false;
+        // GL_MAX_CLIP_DISTANCES. Not ES core in any version - it exists only as
+        // GL_MAX_CLIP_DISTANCES_EXT under GL_EXT_clip_cull_distance - so asking a driver without
+        // the extension raises GL_INVALID_ENUM and leaves the out-param untouched. The "queried"
+        // flag is what pins the gating; the "raises error" knob is what pins the drain.
+        GLint maxClipDistances = 8;
+        bool maxClipDistancesQueried = false;
+        bool clipDistanceQueryRaisesError = false;
+        // GL_MAX_VIEWPORTS / GL_VIEWPORT_SUBPIXEL_BITS / GL_VIEWPORT_BOUNDS_RANGE are
+        // GL_OES_viewport_array state and, like the clip-distance pname, exist nowhere in ES core.
+        GLint maxViewports = 32;
+        GLint viewportSubpixelBits = 8;
+        bool viewportArrayLimitsQueried = false;
+        // GL_LAYER_PROVOKING_VERTEX is ES 3.2 core; GL_VIEWPORT_INDEX_PROVOKING_VERTEX comes with
+        // GL_OES_viewport_array. Both must go unasked where they do not exist, and a driver answer
+        // outside the four legal conventions must not be forwarded as one.
+        GLint layerProvokingVertex = GL_FIRST_VERTEX_CONVENTION;
+        GLint viewportIndexProvokingVertex = GL_LAST_VERTEX_CONVENTION;
+        bool layerProvokingVertexQueried = false;
+        // A driver rejecting one of the UNCONDITIONAL probes. GL_SMOOTH_LINE_WIDTH_RANGE is the
+        // realistic one - it is desktop-only state that every GLES driver refuses - and it stands
+        // in for the whole run: whatever it leaves behind must not reach the application.
+        bool smoothLineWidthQueryRaisesError = false;
+        // What the driver answers for the four multisample ceilings. Zero is the value that has
+        // to be floored away: the frontend would otherwise advertise a sample count it rejects.
+        GLint multisampleCeiling = 4;
         GLfloat minFragmentInterpolationOffset = -0.75f;
         GLfloat maxFragmentInterpolationOffset = 0.625f;
         GLint fragmentInterpolationOffsetBits = 6;
@@ -111,7 +147,30 @@ namespace {
         funcs.glGetIntegerv = [](GLenum pname, GLint* data) {
             switch (pname) {
             case GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS:
-                *data = g_fake.maxVertexSsboBlocks;
+                if (g_fake.perStageSsboBlockQueryRaisesError) {
+                    g_fake.pendingError = GL_INVALID_ENUM;
+                } else {
+                    *data = g_fake.maxVertexSsboBlocks;
+                }
+                break;
+            case GL_MAX_FRAGMENT_SHADER_STORAGE_BLOCKS:
+                if (g_fake.perStageSsboBlockQueryRaisesError) {
+                    g_fake.pendingError = GL_INVALID_ENUM;
+                } else {
+                    *data = g_fake.maxFragmentSsboBlocks;
+                }
+                break;
+            case GL_MAX_TESS_CONTROL_SHADER_STORAGE_BLOCKS:
+                g_fake.tessAndGeometrySsboBlocksQueried = true;
+                *data = g_fake.maxTessControlSsboBlocks;
+                break;
+            case GL_MAX_TESS_EVALUATION_SHADER_STORAGE_BLOCKS:
+                g_fake.tessAndGeometrySsboBlocksQueried = true;
+                *data = g_fake.maxTessEvaluationSsboBlocks;
+                break;
+            case GL_MAX_GEOMETRY_SHADER_STORAGE_BLOCKS:
+                g_fake.tessAndGeometrySsboBlocksQueried = true;
+                *data = g_fake.maxGeometrySsboBlocks;
                 break;
             case GL_MAX_VERTEX_IMAGE_UNIFORMS:
                 *data = g_fake.maxVertexImageUniforms;
@@ -126,6 +185,37 @@ namespace {
             case GL_MAX_COMPUTE_IMAGE_UNIFORMS:
                 *data = g_fake.maxComputeImageUniforms;
                 break;
+            case GL_MAX_CLIP_DISTANCES:
+                g_fake.maxClipDistancesQueried = true;
+                if (g_fake.clipDistanceQueryRaisesError) {
+                    g_fake.pendingError = GL_INVALID_ENUM;
+                } else {
+                    *data = g_fake.maxClipDistances;
+                }
+                break;
+            case GL_MAX_VIEWPORTS:
+                g_fake.viewportArrayLimitsQueried = true;
+                *data = g_fake.maxViewports;
+                break;
+            case GL_VIEWPORT_SUBPIXEL_BITS:
+                g_fake.viewportArrayLimitsQueried = true;
+                *data = g_fake.viewportSubpixelBits;
+                break;
+            case GL_VIEWPORT_INDEX_PROVOKING_VERTEX:
+                g_fake.viewportArrayLimitsQueried = true;
+                *data = g_fake.viewportIndexProvokingVertex;
+                break;
+            case GL_LAYER_PROVOKING_VERTEX:
+                g_fake.layerProvokingVertexQueried = true;
+                *data = g_fake.layerProvokingVertex;
+                break;
+            case GL_MAX_COLOR_TEXTURE_SAMPLES:
+            case GL_MAX_DEPTH_TEXTURE_SAMPLES:
+            case GL_MAX_FRAMEBUFFER_SAMPLES:
+            case GL_MAX_INTEGER_SAMPLES:
+            case GL_MAX_SAMPLES:
+                *data = g_fake.multisampleCeiling;
+                break;
             case GL_FRAGMENT_INTERPOLATION_OFFSET_BITS:
                 g_fake.fragmentInterpolationLimitsQueried = true;
                 if (g_fake.fragmentInterpolationQueryRaisesError) {
@@ -205,11 +295,22 @@ namespace {
                     data[0] = g_fake.maxFragmentInterpolationOffset;
                 }
                 break;
+            case GL_SMOOTH_LINE_WIDTH_RANGE:
+                if (g_fake.smoothLineWidthQueryRaisesError) {
+                    g_fake.pendingError = GL_INVALID_ENUM;
+                } else {
+                    data[0] = 0.0f;
+                    data[1] = 0.0f;
+                }
+                break;
+            case GL_VIEWPORT_BOUNDS_RANGE:
+                g_fake.viewportArrayLimitsQueried = true;
+                data[0] = 0.0f;
+                data[1] = 0.0f;
+                break;
             // Two-component range queries.
             case GL_ALIASED_LINE_WIDTH_RANGE:
-            case GL_SMOOTH_LINE_WIDTH_RANGE:
             case GL_ALIASED_POINT_SIZE_RANGE:
-            case GL_VIEWPORT_BOUNDS_RANGE:
                 data[0] = 0.0f;
                 data[1] = 0.0f;
                 break;
@@ -400,6 +501,10 @@ namespace {
     MobileGL::MG_External::GLESCapabilities MakeEs31Capabilities() {
         MobileGL::MG_External::GLESCapabilities caps;
         caps.GLESVersion = {3, 1, 0};
+        // The probe reads its vertex storage-block gate from caps rather than re-querying the
+        // driver (FillInGLESCapabilities resolves the per-stage limits before calling it), so a
+        // caps struct handed to the probe directly has to carry what the fake reports.
+        caps.MaxVertexShaderStorageBlocks = g_fake.maxVertexSsboBlocks;
         return caps;
     }
 
@@ -527,6 +632,263 @@ TEST(ImageUniformCapabilities, QueriesRealPerStageLimitsAndConservativelyGatesGe
     EXPECT_TRUE(g_fake.maxGeometryImageUniformsQueried);
 }
 
+// The per-stage GL_MAX_*_SHADER_STORAGE_BLOCKS probes. These decide whether an application is
+// told it may declare a storage block in a graphics stage, and on a driver that cannot serve one
+// a wrong answer is not a cosmetic mis-report: the program is built, the driver refuses it at
+// link time, the frontend reports LINK_STATUS true anyway, and every draw with it renders
+// nothing. A Mali-G925-Immortalis reports 0 for vertex, both tessellation stages and geometry.
+TEST(PerStageStorageBlockCapabilities, TakesTheDriverValuesAndGatesTessAndGeometryOnEs32) {
+    const auto funcs = MakeFakeGLESFunctions();
+
+    // ES 3.1: the tessellation and geometry pnames do not exist, so they must not be asked for
+    // and the stages must report the spec minimum of 0 rather than a hopeful driver number.
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 3;
+    MobileGL::MG_External::GLESCapabilities es31Caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(es31Caps, funcs));
+    EXPECT_EQ(es31Caps.MaxVertexShaderStorageBlocks, 3);
+    EXPECT_EQ(es31Caps.MaxFragmentShaderStorageBlocks, g_fake.maxFragmentSsboBlocks);
+    EXPECT_EQ(es31Caps.MaxTessControlShaderStorageBlocks, 0);
+    EXPECT_EQ(es31Caps.MaxTessEvaluationShaderStorageBlocks, 0);
+    EXPECT_EQ(es31Caps.MaxGeometryShaderStorageBlocks, 0);
+    EXPECT_FALSE(g_fake.tessAndGeometrySsboBlocksQueried);
+
+    // ES 3.2: all five are real pnames and all five driver values must come through verbatim.
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 3;
+    g_fake.glesMinorVersion = 2;
+    MobileGL::MG_External::GLESCapabilities es32Caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(es32Caps, funcs));
+    EXPECT_EQ(es32Caps.MaxVertexShaderStorageBlocks, 3);
+    EXPECT_EQ(es32Caps.MaxTessControlShaderStorageBlocks, g_fake.maxTessControlSsboBlocks);
+    EXPECT_EQ(es32Caps.MaxTessEvaluationShaderStorageBlocks, g_fake.maxTessEvaluationSsboBlocks);
+    EXPECT_EQ(es32Caps.MaxGeometryShaderStorageBlocks, g_fake.maxGeometrySsboBlocks);
+    EXPECT_EQ(es32Caps.MaxFragmentShaderStorageBlocks, g_fake.maxFragmentSsboBlocks);
+    EXPECT_TRUE(g_fake.tessAndGeometrySsboBlocksQueried);
+}
+
+// Zero has to survive the round trip intact. It is the answer that matters most - it is what
+// ARM's driver actually reports - so a probe that silently substituted a floor would put the
+// bug straight back.
+TEST(PerStageStorageBlockCapabilities, AZeroFromTheDriverIsReportedAsZero) {
+    const auto funcs = MakeFakeGLESFunctions();
+
+    ResetFakeDriver();
+    g_fake.glesMinorVersion = 2;
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.maxTessControlSsboBlocks = 0;
+    g_fake.maxTessEvaluationSsboBlocks = 0;
+    g_fake.maxGeometrySsboBlocks = 0;
+    g_fake.maxFragmentSsboBlocks = 16;
+
+    MobileGL::MG_External::GLESCapabilities maliLikeCaps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(maliLikeCaps, funcs));
+
+    EXPECT_EQ(maliLikeCaps.MaxVertexShaderStorageBlocks, 0);
+    EXPECT_EQ(maliLikeCaps.MaxTessControlShaderStorageBlocks, 0);
+    EXPECT_EQ(maliLikeCaps.MaxTessEvaluationShaderStorageBlocks, 0);
+    EXPECT_EQ(maliLikeCaps.MaxGeometryShaderStorageBlocks, 0);
+    EXPECT_EQ(maliLikeCaps.MaxFragmentShaderStorageBlocks, 16);
+}
+
+// A rejected query must leave no error behind for the application's first glGetError to find,
+// and must fall back to the spec minimums rather than to whatever the untouched out-param held.
+TEST(PerStageStorageBlockCapabilities, ARejectedQueryIsDrainedAndFallsBackToTheSpecMinimums) {
+    const auto funcs = MakeFakeGLESFunctions();
+
+    ResetFakeDriver();
+    g_fake.perStageSsboBlockQueryRaisesError = true;
+    g_fake.maxVertexSsboBlocks = 12;
+    g_fake.maxFragmentSsboBlocks = 12;
+
+    MobileGL::MG_External::GLESCapabilities caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(caps, funcs));
+
+    EXPECT_EQ(caps.MaxVertexShaderStorageBlocks, 0);
+    EXPECT_EQ(caps.MaxFragmentShaderStorageBlocks, 4);
+    EXPECT_EQ(g_fake.pendingError, static_cast<GLenum>(GL_NO_ERROR));
+}
+
+// GL_MAX_CLIP_DISTANCES is the same defect as the per-stage storage blocks above, one pname
+// over: the query does not exist without GL_EXT_clip_cull_distance, so an unguarded probe left
+// an optimistic 8 behind on every ARM driver. Advertising eight clip planes a driver cannot host
+// does not make gl_ClipDistance work - SPIRV-Cross emits it behind an `#extension ... : require`
+// the ESSL compiler rejects, DirectGLES has nowhere to put the per-distance enables, and the
+// draw renders nothing while LINK_STATUS says everything is fine.
+TEST(ClipDistanceCapabilities, NoExtensionMeansNoClipDistancesAndNoQuery) {
+    const auto funcs = MakeFakeGLESFunctions();
+
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+
+    MobileGL::MG_External::GLESCapabilities caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(caps, funcs));
+
+    EXPECT_FALSE(caps.SupportsClipDistance);
+    EXPECT_EQ(caps.MaxClipDistances, 0);
+    EXPECT_FALSE(g_fake.maxClipDistancesQueried)
+        << "GL_MAX_CLIP_DISTANCES is not ES core; asking for it without the extension only leaks "
+           "a GL_INVALID_ENUM";
+}
+
+// The other half of the same claim, and the one that keeps this from being a blanket zero: a
+// driver that HAS the extension must have its real limit come through untouched. Adreno does,
+// and it passes the clip-distance conformance cases on the strength of it.
+TEST(ClipDistanceCapabilities, TheExtensionIsQueriedAndItsLimitIsReportedVerbatim) {
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.extensions.emplace_back("GL_EXT_clip_cull_distance");
+    g_fake.maxClipDistances = 6;
+    const auto funcs = MakeFakeGLESFunctions();
+
+    MobileGL::MG_External::GLESCapabilities caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(caps, funcs));
+
+    EXPECT_TRUE(caps.SupportsClipDistance);
+    EXPECT_TRUE(g_fake.maxClipDistancesQueried);
+    EXPECT_EQ(caps.MaxClipDistances, 6);
+}
+
+// A driver that advertises the extension and then refuses the query is a driver fault, not a
+// missing feature - but the answer has to be the honest zero either way, and the error must not
+// be left for the application's first glGetError to find.
+TEST(ClipDistanceCapabilities, ARejectedQueryIsDrainedAndReportsZero) {
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.extensions.emplace_back("GL_EXT_clip_cull_distance");
+    g_fake.clipDistanceQueryRaisesError = true;
+    const auto funcs = MakeFakeGLESFunctions();
+
+    MobileGL::MG_External::GLESCapabilities caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(caps, funcs));
+
+    EXPECT_TRUE(g_fake.maxClipDistancesQueried);
+    EXPECT_EQ(caps.MaxClipDistances, 0);
+    EXPECT_EQ(funcs.glGetError(), GL_NO_ERROR) << "the failed query must not leave an error behind";
+}
+
+// The same defect one more time, for the three GL_OES_viewport_array pnames. Their advertised
+// values do not come from the driver (GL_Getter answers GL_MAX_VIEWPORTS from the frontend state
+// width and floors GL_SUBPIXEL_BITS at its own constant), so what this pins is the other half of
+// the class defect: a pname that does not exist must not be asked for, because the GL_INVALID_ENUM
+// it raises is then attributed to whatever the application calls next.
+TEST(ViewportArrayCapabilities, TheLimitsAreOnlyAskedForWhenTheExtensionIsPresent) {
+    const auto funcs = MakeFakeGLESFunctions();
+
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    MobileGL::MG_External::GLESCapabilities withoutCaps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(withoutCaps, funcs));
+    EXPECT_FALSE(withoutCaps.SupportsViewportArray);
+    EXPECT_FALSE(g_fake.viewportArrayLimitsQueried);
+    EXPECT_EQ(withoutCaps.MaxViewports, 16) << "the OpenGL core minimum, not a driver answer";
+    EXPECT_FLOAT_EQ(withoutCaps.ViewportBoundsRangeMin, -32768.0f);
+    EXPECT_FLOAT_EQ(withoutCaps.ViewportBoundsRangeMax, 32767.0f);
+
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.extensions.emplace_back("GL_OES_viewport_array");
+    MobileGL::MG_External::GLESCapabilities withCaps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(withCaps, funcs));
+    EXPECT_TRUE(withCaps.SupportsViewportArray);
+    EXPECT_TRUE(g_fake.viewportArrayLimitsQueried);
+    EXPECT_EQ(withCaps.MaxViewports, g_fake.maxViewports);
+    EXPECT_EQ(withCaps.ViewportSubpixelBits, g_fake.viewportSubpixelBits);
+}
+
+// GL_LAYER_PROVOKING_VERTEX and GL_VIEWPORT_INDEX_PROVOKING_VERTEX name which vertex of a
+// primitive supplies gl_Layer and gl_ViewportIndex. MobileGL used to answer a hard-coded
+// GL_LAST_VERTEX_CONVENTION for both, derived from nothing, and got it wrong on both test devices
+// in OPPOSITE directions. GL_UNDEFINED_VERTEX is a legal answer (GL 4.6 table 23.65) and it is
+// the honest one wherever the capability that would give the convention meaning is absent.
+TEST(ProvokingVertexConventions, AreTakenFromTheDriverOnlyWhereThePnameExists) {
+    const auto funcs = MakeFakeGLESFunctions();
+
+    // ES 3.1, no viewport array: neither pname exists, so neither is asked for.
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    MobileGL::MG_External::GLESCapabilities es31Caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(es31Caps, funcs));
+    EXPECT_FALSE(g_fake.layerProvokingVertexQueried);
+    EXPECT_EQ(es31Caps.LayerProvokingVertex, static_cast<GLenum>(GL_UNDEFINED_VERTEX));
+    EXPECT_EQ(es31Caps.ViewportIndexProvokingVertex, static_cast<GLenum>(GL_UNDEFINED_VERTEX));
+
+    // ES 3.2 with the viewport array: both exist and both driver answers come through verbatim.
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.glesMinorVersion = 2;
+    g_fake.extensions.emplace_back("GL_OES_viewport_array");
+    MobileGL::MG_External::GLESCapabilities es32Caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(es32Caps, funcs));
+    EXPECT_TRUE(g_fake.layerProvokingVertexQueried);
+    EXPECT_EQ(es32Caps.LayerProvokingVertex, static_cast<GLenum>(GL_FIRST_VERTEX_CONVENTION));
+    EXPECT_EQ(es32Caps.ViewportIndexProvokingVertex, static_cast<GLenum>(GL_LAST_VERTEX_CONVENTION));
+
+    // ES 3.2 WITHOUT the viewport array - the shape of both test devices. The layer convention is
+    // real and comes from the driver; the viewport-index one describes a selection that never
+    // happens, because only viewport 0 is ever rasterized, and stays undefined.
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.glesMinorVersion = 2;
+    MobileGL::MG_External::GLESCapabilities deviceLikeCaps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(deviceLikeCaps, funcs));
+    EXPECT_EQ(deviceLikeCaps.LayerProvokingVertex, static_cast<GLenum>(GL_FIRST_VERTEX_CONVENTION));
+    EXPECT_EQ(deviceLikeCaps.ViewportIndexProvokingVertex, static_cast<GLenum>(GL_UNDEFINED_VERTEX));
+}
+
+// A driver answering something that is not one of the four legal conventions must not have it
+// forwarded as one: GL_UNDEFINED_VERTEX describes "MobileGL cannot tell you" exactly.
+TEST(ProvokingVertexConventions, AnIllegalDriverAnswerBecomesUndefined) {
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.glesMinorVersion = 2;
+    g_fake.layerProvokingVertex = 0x1234;
+    const auto funcs = MakeFakeGLESFunctions();
+
+    MobileGL::MG_External::GLESCapabilities caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(caps, funcs));
+
+    EXPECT_TRUE(g_fake.layerProvokingVertexQueried);
+    EXPECT_EQ(caps.LayerProvokingVertex, static_cast<GLenum>(GL_UNDEFINED_VERTEX));
+}
+
+// The multisample ceilings are ES 3.1 state; a driver that answers zero - or an older context
+// that answers nothing - must not have that reach GL_Getter, which would then reject the sample
+// count it just advertised.
+TEST(MultisampleCapabilities, TheAdvertisedSampleCountsNeverFallBelowOne) {
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.multisampleCeiling = 0;
+    const auto funcs = MakeFakeGLESFunctions();
+
+    MobileGL::MG_External::GLESCapabilities caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(caps, funcs));
+
+    EXPECT_EQ(caps.MaxColorTextureSamples, 1);
+    EXPECT_EQ(caps.MaxDepthTextureSamples, 1);
+    EXPECT_EQ(caps.MaxFramebufferSamples, 1);
+    EXPECT_EQ(caps.MaxIntegerSamples, 1);
+    EXPECT_EQ(caps.MaxSamples, 1);
+    EXPECT_EQ(caps.MaxSampleMaskWords, 1);
+}
+
+// The whole point of the drain, stated once at the level that matters: capability init is the
+// first thing that ever touches the driver, so an error it leaves behind surfaces at the
+// APPLICATION's first glGetError and is blamed on an unrelated call. GL_SMOOTH_LINE_WIDTH_RANGE
+// is the stand-in because it is desktop-only state that every real GLES driver refuses.
+TEST(CapabilityProbeHygiene, ARejectedUnconditionalProbeLeavesNoErrorBehind) {
+    ResetFakeDriver();
+    g_fake.maxVertexSsboBlocks = 0;
+    g_fake.smoothLineWidthQueryRaisesError = true;
+    const auto funcs = MakeFakeGLESFunctions();
+
+    MobileGL::MG_External::GLESCapabilities caps;
+    ASSERT_TRUE(MobileGL::MG_Util::BackendLoader::FillInGLESCapabilities(caps, funcs));
+
+    EXPECT_EQ(funcs.glGetError(), GL_NO_ERROR)
+        << "capability init must not hand the application an error it never caused";
+}
+
 TEST(FragmentInterpolationCapabilities, QueriesOnlyWhenSupportedAndPreservesDriverLimits) {
     const auto funcs = MakeFakeGLESFunctions();
 

MobileGL/MG_Test/Buffer/BufferTest.cpp

@@ -8,6 +8,7 @@
 
 #include <gtest/gtest.h>
 
+#include <cstdint>
 #include <limits>
 
 #include "Includes.h"
@@ -267,6 +268,116 @@ TEST_F(BufferTest, AcquireMemoryRangeWithExplicit) {
     ASSERT_EQ(actual, expected);
 }
 
+// GL_MIN_MAP_BUFFER_ALIGNMENT is a promise about POINTERS, and MobileGL used to keep only the
+// query half of it: glGetIntegerv answered 64 while every mapped pointer came out of a plain
+// std::vector, aligned to alignof(std::max_align_t) - 16 on aarch64. GL 4.2 /
+// ARB_map_buffer_alignment fix the minimum at 64, so under-reporting is not available and the
+// implementation has to be brought up to the number instead. Note the two different constraints:
+// glMapBuffer's pointer must be aligned outright, while glMapBufferRange's must be aligned AFTER
+// subtracting the offset the caller asked for - i.e. it sits at the offset's own alignment phase.
+// KHR-GLxx.map_buffer_alignment.functional asserts exactly these two, at offset 63, for 24
+// storage-flag combinations across 14 targets, and failed identically on both test devices.
+TEST_F(BufferTest, MappedPointersHonourTheAdvertisedMapBufferAlignment) {
+    GLint advertisedAlignment = 0;
+    MobileGL::MG_Impl::GLImpl::GetIntegerv(GL_MIN_MAP_BUFFER_ALIGNMENT, &advertisedAlignment);
+    ASSERT_EQ(advertisedAlignment, static_cast<GLint>(MobileGL::MG_State::GLState::MIN_MAP_BUFFER_ALIGNMENT))
+        << "the query and the allocator must read the same constant";
+    ASSERT_GE(advertisedAlignment, 64) << "GL 4.2 fixes the minimum at 64";
+    const SizeT alignment = static_cast<SizeT>(advertisedAlignment);
+
+    auto& slot = MobileGL::MG_State::pGLContext->GetBufferBindingSlot(BufferTarget::Uniform);
+    Vector<Uint> bufferNames;
+    MobileGL::MG_State::pGLContext->GenBufferNames(1, bufferNames);
+    auto bufObj = MobileGL::MG_State::pGLContext->CreateBufferObject(bufferNames[0]);
+    slot.Bind(bufObj);
+
+    // The conformance test's own shape: a buffer two alignments long, mapped from the last byte
+    // inside the first alignment - the offset most likely to expose a base-aligned-only fix.
+    const SizeT bufferSize = 2 * alignment;
+    const SizeT offset = alignment - 1;
+    bufObj->Resize(bufferSize);
+    Vector<Uint8> initData(bufferSize);
+    for (SizeT i = 0; i < bufferSize; ++i) initData[i] = static_cast<Uint8>(i);
+    bufObj->UploadData(DataPtr{.data = initData.data(), .size = bufferSize}, 0);
+
+    const auto addressOf = [](const void* pointer) { return reinterpret_cast<std::uintptr_t>(pointer); };
+
+    // glMapBuffer, read-only: the shadow base itself is handed out.
+    void* readMapped = bufObj->AcquireMemory(true, true, false);
+    ASSERT_NE(readMapped, nullptr);
+    EXPECT_EQ(addressOf(readMapped) % alignment, 0u) << "glMapBuffer(GL_READ_ONLY) returned an unaligned pointer";
+    bufObj->ReleaseMemory();
+
+    // glMapBuffer, write: the staging store is handed out instead.
+    void* writeMapped = bufObj->AcquireMemory(true, false, true);
+    ASSERT_NE(writeMapped, nullptr);
+    EXPECT_EQ(addressOf(writeMapped) % alignment, 0u) << "glMapBuffer(GL_WRITE_ONLY) returned an unaligned pointer";
+    EXPECT_EQ(bufObj->GetMappedPointer(), writeMapped)
+        << "GL_BUFFER_MAP_POINTER must report the pointer the map returned";
+    bufObj->ReleaseMemory();
+
+    // glMapBufferRange, read-only: shadow base + offset, so the phase falls out for free.
+    const Range1D mapRange{.start = offset, .end = bufferSize};
+    void* rangeRead = bufObj->AcquireMemoryRange(mapRange, BufferMappingAccessBit::Read);
+    ASSERT_NE(rangeRead, nullptr);
+    EXPECT_EQ((addressOf(rangeRead) - offset) % alignment, 0u)
+        << "glMapBufferRange(READ) returned a pointer whose base is unaligned";
+    bufObj->ReleaseMemory();
+
+    // glMapBufferRange, write: the staging store has to be biased to the same phase, and the
+    // write-back has to follow the bias or the bytes land at the wrong place in the shadow.
+    Uint8* rangeWrite = static_cast<Uint8*>(bufObj->AcquireMemoryRange(mapRange, BufferMappingAccessBit::Write));
+    ASSERT_NE(rangeWrite, nullptr);
+    EXPECT_EQ((addressOf(rangeWrite) - offset) % alignment, 0u)
+        << "glMapBufferRange(WRITE) returned a pointer whose base is unaligned";
+    EXPECT_EQ(bufObj->GetMappedPointer(), rangeWrite)
+        << "GL_BUFFER_MAP_POINTER must report the pointer the map returned";
+    // Seeded from the shadow, so the mapped view starts at the offset's byte.
+    EXPECT_EQ(rangeWrite[0], static_cast<Uint8>(offset));
+    rangeWrite[0] = 0xAB;
+    rangeWrite[bufferSize - offset - 1] = 0xCD;
+    bufObj->ReleaseMemory();
+
+    Vector<Uint8> readBack(bufferSize);
+    bufObj->DownloadSubData(readBack.data(), 0, bufferSize);
+    EXPECT_EQ(readBack[offset], 0xAB) << "the biased staging write-back landed at the wrong offset";
+    EXPECT_EQ(readBack[bufferSize - 1], 0xCD) << "the biased staging write-back landed at the wrong offset";
+    EXPECT_EQ(readBack[offset - 1], static_cast<Uint8>(offset - 1)) << "the write-back overran the mapped range";
+}
+
+// The explicit-flush path reads through the same bias, one flush offset further in: a flush of
+// [offset + 4, offset + 8) must copy the bytes the application wrote at rangeWrite[4..8), not the
+// ones sitting four bytes into the raw allocation.
+TEST_F(BufferTest, ExplicitFlushOfARangeMapFollowsTheAlignmentBias) {
+    auto& slot = MobileGL::MG_State::pGLContext->GetBufferBindingSlot(BufferTarget::Uniform);
+    Vector<Uint> bufferNames;
+    MobileGL::MG_State::pGLContext->GenBufferNames(1, bufferNames);
+    auto bufObj = MobileGL::MG_State::pGLContext->CreateBufferObject(bufferNames[0]);
+    slot.Bind(bufObj);
+
+    const SizeT alignment = MobileGL::MG_State::GLState::MIN_MAP_BUFFER_ALIGNMENT;
+    const SizeT bufferSize = 2 * alignment;
+    const SizeT offset = alignment - 1;
+    bufObj->Resize(bufferSize);
+    Vector<Uint8> initData(bufferSize, 0);
+    bufObj->UploadData(DataPtr{.data = initData.data(), .size = bufferSize}, 0);
+
+    const Range1D mapRange{.start = offset, .end = bufferSize};
+    Uint8* mapped = static_cast<Uint8*>(bufObj->AcquireMemoryRange(
+        mapRange, BufferMappingAccessBit::Write | BufferMappingAccessBit::FlushExplicit));
+    ASSERT_NE(mapped, nullptr);
+    mapped[4] = 0x5A;
+    mapped[5] = 0x5B;
+    bufObj->FlushMemoryRange(4, 2);
+    bufObj->ReleaseMemory();
+
+    Vector<Uint8> readBack(bufferSize);
+    bufObj->DownloadSubData(readBack.data(), 0, bufferSize);
+    EXPECT_EQ(readBack[offset + 4], 0x5A);
+    EXPECT_EQ(readBack[offset + 5], 0x5B);
+    EXPECT_EQ(readBack[offset + 3], 0x00) << "the explicit flush copied bytes outside the flushed range";
+}
+
 TEST_F(BufferTest, CopyBufferSubData) {
     auto& srcSlot = MobileGL::MG_State::pGLContext->GetBufferBindingSlot(BufferTarget::CopyRead);
     auto& dstSlot = MobileGL::MG_State::pGLContext->GetBufferBindingSlot(BufferTarget::CopyWrite);

MobileGL/MG_Test/Program/ProgramInterfaceTest.cpp

@@ -716,6 +716,177 @@ void main() {
         EXPECT_EQ(TakeError(), GL_INVALID_ENUM);
     }
 
+    // Two counters that share a binding AND an offset must fail to link. glslang's own check
+    // lives in fixOffset(), which the Vulkan-relaxed parse never reaches - it folds the
+    // atomic_uint into a storage block and returns from declareVariable() first - so the pair
+    // used to link cleanly and then increment the same four bytes.
+    TEST_F(ProgramInterfaceTest, OverlappingAtomicCounterOffsetsFailToLink) {
+        const char* fs = R"(#version 430
+out vec4 color;
+layout (binding = 0, offset = 0) uniform atomic_uint a;
+layout (binding = 0, offset = 0) uniform atomic_uint b;
+void main() { color = vec4(float(atomicCounterIncrement(a) + atomicCounterIncrement(b))); }
+)";
+        const GLuint p = MakeProgram(kSimpleVs, fs);
+        LinkProgram(p);
+        GLint status = -1;
+        GetProgramiv(p, GL_LINK_STATUS, &status);
+        EXPECT_EQ(status, GL_FALSE);
+        char log[4096] = "";
+        GetProgramInfoLog(p, sizeof(log), nullptr, log);
+        EXPECT_NE(std::string(log).find("overlap"), std::string::npos) << "info log was: " << log;
+        ClearErrors();
+
+        // Distinct offsets at one binding, and the same offset at two different bindings, are
+        // both legal and must still link - a check keyed any wider would reject them.
+        const char* legalFs = R"(#version 430
+out vec4 color;
+layout (binding = 0, offset = 0) uniform atomic_uint a;
+layout (binding = 0, offset = 4) uniform atomic_uint b;
+layout (binding = 1, offset = 0) uniform atomic_uint c;
+void main() {
+   color = vec4(float(atomicCounterIncrement(a) + atomicCounterIncrement(b) + atomicCounterIncrement(c)));
+}
+)";
+        const GLuint legal = MakeProgram(kSimpleVs, legalFs);
+        LinkProgram(legal);
+        ExpectLinked(legal);
+        ClearErrors();
+    }
+
+    // GL 4.6 core 7.6 fails the link when a stage's active image uniforms exceed
+    // GL_MAX_*_IMAGE_UNIFORMS, or when their sum exceeds GL_MAX_COMBINED_IMAGE_UNIFORMS. Nothing
+    // counted them - glslang keeps those numbers only so gl_Max*ImageUniforms can expand from
+    // them - so every deliberately-oversized program in
+    // KHR-GL4x.shader_image_load_store.uniform-limits linked cleanly and then rendered nothing.
+    //
+    // Sized off the ADVERTISED limits rather than a constant, because the numbers come from the
+    // active backend and the whole point of the check is that the two agree.
+    TEST_F(ProgramInterfaceTest, ImageUniformsOverAStageLimitFailToLink) {
+        GLint maxFragmentImages = 0;
+        GLint maxCombinedImages = 0;
+        GetIntegerv(GL_MAX_FRAGMENT_IMAGE_UNIFORMS, &maxFragmentImages);
+        GetIntegerv(GL_MAX_COMBINED_IMAGE_UNIFORMS, &maxCombinedImages);
+        ClearErrors();
+        ASSERT_GT(maxFragmentImages, 0);
+
+        // The fragment stage is compiled explicitly so a COMPILE failure can never be mistaken
+        // for the link failure under test.
+        const auto linkWithFragmentImages = [](GLint count) {
+            const std::string n = std::to_string(count);
+            const std::string source = std::string(R"(#version 430
+out vec4 color;
+layout(r32i) uniform iimage2D u_image[)") + n + R"(];
+void main() {
+    int value = 1;
+    for (int i = 0; i < )" + n + R"(; ++i) {
+        value = imageAtomicAdd(u_image[i], ivec2(0), value);
+    }
+    color = vec4(float(value));
+}
+)";
+            const char* sourcePtr = source.c_str();
+            const GLuint fs = CreateShader(GL_FRAGMENT_SHADER);
+            ShaderSource(fs, 1, &sourcePtr, nullptr);
+            CompileShader(fs);
+            GLint compiled = 0;
+            GetShaderiv(fs, GL_COMPILE_STATUS, &compiled);
+            EXPECT_EQ(compiled, GL_TRUE) << "the fragment stage with " << count << " image uniforms must compile";
+
+            const GLuint vs = CreateShader(GL_VERTEX_SHADER);
+            ShaderSource(vs, 1, &kSimpleVs, nullptr);
+            CompileShader(vs);
+
+            const GLuint program = CreateProgram();
+            AttachShader(program, vs);
+            AttachShader(program, fs);
+            LinkProgram(program);
+            return program;
+        };
+
+        const GLuint over = linkWithFragmentImages(maxFragmentImages + 1);
+        GLint status = -1;
+        GetProgramiv(over, GL_LINK_STATUS, &status);
+        EXPECT_EQ(status, GL_FALSE);
+        char log[4096] = "";
+        GetProgramInfoLog(over, sizeof(log), nullptr, log);
+        EXPECT_NE(std::string(log).find("GL_MAX_FRAGMENT_IMAGE_UNIFORMS"), std::string::npos)
+            << "info log was: " << log;
+        ClearErrors();
+
+        // Exactly AT the limit is legal and must still link: the comparison is strictly
+        // greater-than, and the conformance suite's combined-stage subcase builds a program that
+        // fills every stage to its own limit and expects it to link whenever the combined limit
+        // can hold them.
+        if (maxFragmentImages <= maxCombinedImages) {
+            const GLuint atLimit = linkWithFragmentImages(maxFragmentImages);
+            ExpectLinked(atLimit);
+            ClearErrors();
+        }
+    }
+
+    // glGetProgramiv(GL_ACTIVE_ATOMIC_COUNTER_BUFFERS) and glGetActiveAtomicCounterBufferiv are
+    // the pre-4.3 spelling of the interface above, and the spec requires the two to agree.
+    // Neither did: the first counted glslang's atomic counter UNIFORMS - zero, because the
+    // relaxed parse folds every atomic_uint into a storage block before reflection runs - and
+    // the second was a stub that wrote nothing and raised nothing.
+    TEST_F(ProgramInterfaceTest, ActiveAtomicCounterBufferQueriesMatchTheInterface) {
+        const char* fs = R"(#version 430
+out vec4 color;
+layout (binding = 1, offset = 0) uniform atomic_uint a;
+layout (binding = 2, offset = 0) uniform atomic_uint b;
+layout (binding = 2, offset = 4) uniform atomic_uint c;
+void main() {
+   color = vec4(float(atomicCounterIncrement(a) + atomicCounterIncrement(b) + atomicCounterIncrement(c)));
+}
+)";
+        const GLuint p = MakeProgram(kSimpleVs, fs);
+        LinkProgram(p);
+        ExpectLinked(p);
+        ClearErrors();
+
+        GLint bufferCount = -12345;
+        GetProgramiv(p, GL_ACTIVE_ATOMIC_COUNTER_BUFFERS, &bufferCount);
+        EXPECT_EQ(bufferCount, Interfaceiv(p, GL_ATOMIC_COUNTER_BUFFER, GL_ACTIVE_RESOURCES));
+        ASSERT_EQ(bufferCount, 2);
+
+        const auto activeBufferiv = [p](GLuint index, GLenum pname) {
+            GLint value = -12345;
+            GetActiveAtomicCounterBufferiv(p, index, pname, &value);
+            return value;
+        };
+        for (GLuint index = 0; index < static_cast<GLuint>(bufferCount); ++index) {
+            const std::vector<GLint> viaInterface =
+                Props(p, GL_ATOMIC_COUNTER_BUFFER, index,
+                      {GL_BUFFER_BINDING, GL_BUFFER_DATA_SIZE, GL_NUM_ACTIVE_VARIABLES,
+                       GL_REFERENCED_BY_VERTEX_SHADER, GL_REFERENCED_BY_FRAGMENT_SHADER});
+            ASSERT_EQ(viaInterface.size(), 5u);
+            EXPECT_EQ(activeBufferiv(index, GL_ATOMIC_COUNTER_BUFFER_BINDING), viaInterface[0]);
+            EXPECT_EQ(activeBufferiv(index, GL_ATOMIC_COUNTER_BUFFER_DATA_SIZE), viaInterface[1]);
+            EXPECT_EQ(activeBufferiv(index, GL_ATOMIC_COUNTER_BUFFER_ACTIVE_ATOMIC_COUNTERS), viaInterface[2]);
+            EXPECT_EQ(activeBufferiv(index, GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_VERTEX_SHADER), viaInterface[3]);
+            EXPECT_EQ(activeBufferiv(index, GL_ATOMIC_COUNTER_BUFFER_REFERENCED_BY_FRAGMENT_SHADER), viaInterface[4]);
+
+            // The counter indices are the GL_UNIFORM indices, in the same order.
+            const std::vector<GLint> expectedIndices = Props(p, GL_ATOMIC_COUNTER_BUFFER, index, {GL_ACTIVE_VARIABLES});
+            ASSERT_FALSE(expectedIndices.empty());
+            std::vector<GLint> indices(expectedIndices.size(), -12345);
+            GetActiveAtomicCounterBufferiv(p, index, GL_ATOMIC_COUNTER_BUFFER_ACTIVE_ATOMIC_COUNTER_INDICES,
+                                           indices.data());
+            EXPECT_EQ(indices, expectedIndices);
+        }
+        EXPECT_EQ(TakeError(), GL_NO_ERROR);
+
+        GLint sink = -12345;
+        GetActiveAtomicCounterBufferiv(p, static_cast<GLuint>(bufferCount), GL_ATOMIC_COUNTER_BUFFER_BINDING, &sink);
+        EXPECT_EQ(TakeError(), GL_INVALID_VALUE);
+        EXPECT_EQ(sink, -12345) << "a rejected query must not write the caller's output";
+        // The interface-query spelling of the same property is NOT accepted here.
+        GetActiveAtomicCounterBufferiv(p, 0, GL_BUFFER_BINDING, &sink);
+        EXPECT_EQ(TakeError(), GL_INVALID_ENUM);
+        EXPECT_EQ(sink, -12345);
+    }
+
     // --------------------------------------------------------- transform-feedback ------
     TEST_F(ProgramInterfaceTest, TransformFeedbackVaryingTypes) {
         const char* vs = R"(#version 430

MobileGL/MG_Test/Program/ProgramTest.cpp

@@ -3010,21 +3010,38 @@ TEST_F(ProgramTest, TwoShaderObjectsWithIdenticalSourceLinkIndependently) {
     ASSERT_NE(objectA, nullptr);
     ASSERT_NE(objectB, nullptr);
     EXPECT_EQ(objectA->GetShaderSource(), objectB->GetShaderSource());
-    // P0b's layer 2 shares the PREPROCESS and never the parse: glslang's TShader is
-    // consume-once, so a memo hit still has to parse for itself.
+    // WHAT THIS CASE IS ACTUALLY ABOUT: two GL shader names holding the same text must never
+    // end up feeding one TShader to two links, because mapIO mutates the aliased intermediate
+    // and the second link would get a corrupted one. There are now three mechanisms that keep
+    // that true, and which one is in play depends on the mode - so the assertion below is on
+    // the PARSES NOT BEING SHARED, never on where each object's parse came from:
     //
-    // P1 stage 6 shares something stronger when it is active - the whole compile JOB, and
-    // therefore the single parse that job produced - and that sharing is made safe by
-    // ShaderCompileTask::ClaimParsedShader's CAS instead, exactly as it already was for one
-    // shader object attached to two programs. ShaderCompileAdoptionTest is where that is
-    // pinned down (it links both objects and compares the generated SPIR-V). So the
-    // one-parse-per-object assertion belongs to the non-adopting path; the two independent
-    // LINKS below are what both modes have to agree on, and they are the point of this case.
+    //   * P0b layer 2 shares the PREPROCESS and never the parse, so each object parses for
+    //     itself. This was the only mechanism when the case was written.
+    //   * P1 stage 6, when async is active, shares the whole compile JOB and therefore its
+    //     single parse - made safe by ClaimParsedShader's CAS, exactly as it already was for
+    //     one shader object attached to two programs. ShaderCompileAdoptionTest pins that
+    //     down by linking both objects and comparing the generated SPIR-V.
+    //   * The translation memo's compile half (L1c) recognises the second object's source and
+    //     publishes its verdict WITHOUT parsing, so that object legitimately holds no TShader
+    //     at all until a link asks ClaimParsedShader for one. Asserting a non-null parse here
+    //     would be asserting that the parse had NOT been skipped - i.e. testing the absence
+    //     of the optimisation rather than the invariant.
+    //
+    // So the pointer assertion applies only where the two objects are genuinely INDEPENDENT,
+    // i.e. where job adoption is not in play. What every mode has to agree on is the two
+    // independent LINKS below, and they are the real point of this case.
     if (!MG_Util::Async::AsyncShaderCompileActive()) {
-        EXPECT_NE(objectA->GetCompiledShader(), objectB->GetCompiledShader());
+        const auto& shaderA = objectA->GetCompiledShader();
+        const auto& shaderB = objectB->GetCompiledShader();
+        // Either may legitimately hold NO parse: that is an L1c hit, where the AST is made on
+        // demand at link instead. So this asserts they are not the SAME non-null parse, and
+        // deliberately not that both have one - the latter would be asserting that the
+        // optimisation had not happened.
+        if (shaderA != nullptr && shaderB != nullptr) {
+            EXPECT_NE(shaderA, shaderB) << "two independent shader objects share one consume-once parse";
+        }
     }
-    EXPECT_NE(objectA->GetCompiledShader(), nullptr);
-    EXPECT_NE(objectB->GetCompiledShader(), nullptr);
 
     GLuint programA = LinkVsFs(vsA, fsA, GL_TRUE);
     GLuint programB = LinkVsFs(vsB, fsB, GL_TRUE);
@@ -3239,3 +3256,76 @@ TEST_F(ProgramTest, CreateShaderAndCreateShaderProgramvReportTheRightErrorClasse
     EXPECT_NE(program, 0u);
     EXPECT_EQ(GetError(), GL_NO_ERROR);
 }
+
+// ARB_explicit_uniform_location / GL 4.6 core 7.6.1: a `layout(location = N)` uniform reserves N
+// EVEN WHEN IT IS INACTIVE. Dead default-block uniforms are correctly filtered off the GL surface
+// (glGetUniformLocation must answer -1 for them), but the implicit allocator used to walk straight
+// over the location they claimed and hand it to a uniform that never asked for it
+// (KHR-GL43.explicit_uniform_location.uniform-loc-mix-with-implicit3).
+TEST_F(ProgramTest, InactiveExplicitUniformLocationIsStillReserved) {
+    const char* vsSource = R"(#version 430 core
+layout(location = 2) uniform vec4 uDeadAtTwo;
+uniform vec4 uA;
+uniform vec4 uB;
+uniform vec4 uC;
+uniform vec4 uD;
+void main() { gl_Position = uA + uB + uC + uD; }
+)";
+    const char* fsSource = R"(#version 430 core
+out vec4 fragColor;
+void main() { fragColor = vec4(1.0); }
+)";
+    const GLuint vs = CompileShaderChecked(GL_VERTEX_SHADER, vsSource);
+    const GLuint fs = CompileShaderChecked(GL_FRAGMENT_SHADER, fsSource);
+    const GLuint program = LinkVsFs(vs, fs, GL_TRUE);
+
+    // Reserving a location must not resurrect the uniform: it is still inactive to GL.
+    EXPECT_EQ(GetUniformLocation(program, "uDeadAtTwo"), -1);
+
+    for (const char* name : {"uA", "uB", "uC", "uD"}) {
+        const GLint location = GetUniformLocation(program, name);
+        EXPECT_GE(location, 0) << name << " lost its implicit location";
+        EXPECT_NE(location, 2) << name << " was handed the location uDeadAtTwo reserved";
+    }
+    EXPECT_EQ(GetError(), GL_NO_ERROR);
+}
+
+// The GL_MAX_UNIFORM_LOCATIONS boundary, from both sides. MAX_UNIFORM_LOCATIONS - 1 is the LAST
+// LEGAL location: it has to link and read back verbatim
+// (KHR-GL43.explicit_uniform_location.uniform-loc-max), which is only true while the advertised
+// value and what the link accepts are the SAME number - the getter used to advertise one more
+// location than any shader could name.
+//
+// The over-the-ceiling half is asserted through an ARRAY, because that is the only spelling the
+// link gets to judge: a bare `layout(location = MAX)` is already a compile error inside glslang
+// ("location is too large"), while an array's base compiles fine and only its last element passes
+// the ceiling (...uniform-loc-negative-link-max-num-of-locations).
+TEST_F(ProgramTest, ExplicitUniformLocationsHonourMaxUniformLocations) {
+    GLint maxLocations = 0;
+    GetIntegerv(GL_MAX_UNIFORM_LOCATIONS, &maxLocations);
+    ASSERT_GE(maxLocations, 1024) << "GL 4.3 requires at least 1024 uniform locations";
+
+    const char* fsSource = R"(#version 430 core
+out vec4 fragColor;
+void main() { fragColor = vec4(1.0); }
+)";
+    const GLuint fs = CompileShaderChecked(GL_FRAGMENT_SHADER, fsSource);
+
+    {
+        const String source = String("#version 430 core\nlayout(location = ") +
+                              std::to_string(maxLocations - 1) +
+                              ") uniform vec4 uAtLimit;\nvoid main() { gl_Position = uAtLimit; }\n";
+        const GLuint vs = CompileShaderChecked(GL_VERTEX_SHADER, source.c_str());
+        const GLuint program = LinkVsFs(vs, fs, GL_TRUE);
+        EXPECT_EQ(GetUniformLocation(program, "uAtLimit"), maxLocations - 1)
+            << "the last location in the pool is legal and must come back verbatim";
+    }
+    {
+        const String source = String("#version 430 core\nlayout(location = ") +
+                              std::to_string(maxLocations - 4) +
+                              ") uniform vec4 uSpill[8];\nvoid main() { gl_Position = uSpill[0]; }\n";
+        const GLuint vs = CompileShaderChecked(GL_VERTEX_SHADER, source.c_str());
+        (void)LinkVsFs(vs, fs, GL_FALSE);
+    }
+    EXPECT_EQ(GetError(), GL_NO_ERROR);
+}

MobileGL/MG_Test/Program/ProgramUtilTest.cpp

@@ -3840,3 +3840,228 @@ TEST_F(ProgramUtilTest, EsslCoreImageFormatSetIsTheThirteenTheSpecLists) {
     EXPECT_FALSE(ShaderCompiler::GLInternalFormatIsCoreEsslImageFormat(0x8051 /*GL_RGB8*/));
     EXPECT_FALSE(ShaderCompiler::GLInternalFormatIsCoreEsslImageFormat(0 /*GL_NONE*/));
 }
+
+// KHR-GL43.shader_storage_buffer_object.basic-syntax iteration 6. glslang assigns a block's member
+// offsets at DECLARATION time, where a member array that is still unsized contributes zero bytes -
+// so `vec4 position01[]; vec4 position2;` put both members at offset 0 and the shader read
+// position01[0] where it asked for position2. The preprocessor sizes the non-final member from the
+// largest constant index the source uses, which is what the language says it means.
+TEST_F(ProgramUtilTest, ANonFinalUnsizedBufferBlockMemberIsSizedFromItsLargestConstantIndex) {
+    using namespace MG_Util::ShaderTranspiler;
+
+    String source = R"(#version 430 core
+layout(packed) coherent buffer Buffer {
+  vec4 position01[];
+  vec4 position2;
+} g_buffer;
+void main() {
+  if (gl_VertexID == 0) gl_Position = g_buffer.position01[0];
+  else if (gl_VertexID == 1) gl_Position = g_buffer.position01[1];
+  else if (gl_VertexID == 2) gl_Position = g_buffer.position2;
+}
+)";
+    PreprocessShaderSource(ShaderStage::Vertex, source);
+    EXPECT_NE(source.find("vec4 position01[2];"), String::npos) << source;
+    EXPECT_EQ(source.find("position01[];"), String::npos) << source;
+
+    // The LAST member of a storage block is a run-time sized array, which is legal and already
+    // laid out correctly - sizing it would be a wire-format change, not a repair.
+    String lastMember = R"(#version 430 core
+buffer Buffer {
+  vec4 head;
+  vec4 tail[];
+} g_buffer;
+void main() {
+  gl_Position = g_buffer.tail[0] + g_buffer.tail[3];
+}
+)";
+    PreprocessShaderSource(ShaderStage::Vertex, lastMember);
+    EXPECT_NE(lastMember.find("vec4 tail[];"), String::npos) << lastMember;
+
+    // A member the shader subscripts with anything but a literal cannot be sized from the source,
+    // so it is left exactly as it was.
+    String dynamicIndex = R"(#version 430 core
+buffer Buffer {
+  vec4 head[];
+  vec4 tail;
+} g_buffer;
+uniform int g_index;
+void main() {
+  gl_Position = g_buffer.head[g_index] + g_buffer.tail;
+}
+)";
+    PreprocessShaderSource(ShaderStage::Vertex, dynamicIndex);
+    EXPECT_NE(dynamicIndex.find("vec4 head[];"), String::npos) << dynamicIndex;
+
+    // `buffer` is also a member memory qualifier; a declaration that uses it must not be mistaken
+    // for a block header.
+    String memberQualifier = R"(#version 430 core
+coherent buffer Buffer {
+  buffer vec4 position0;
+  vec4 position1[];
+  vec4 position2;
+} g_buffer;
+void main() {
+  gl_Position = g_buffer.position0 + g_buffer.position1[2] + g_buffer.position2;
+}
+)";
+    PreprocessShaderSource(ShaderStage::Vertex, memberQualifier);
+    EXPECT_NE(memberQualifier.find("vec4 position1[3];"), String::npos) << memberQualifier;
+}
+
+// KHR-GL43.shader_storage_buffer_object.negative-glsl-compileTime: a storage block declared at
+// GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS must fail to compile, and so must an arrayed one whose
+// LAST element passes the ceiling. The relaxed Vulkan-rules parse enforces neither.
+TEST_F(ProgramUtilTest, StorageBlockBindingCeilingIsCheckedAtItsExactBoundary) {
+    using namespace MG_Util::ShaderTranspiler;
+
+    constexpr Int kMaxBindings = 36;
+    const auto violation = [](const String& body) {
+        return FindShaderStorageBindingViolation("#version 430 core\n" + body + "void main() {}\n", kMaxBindings);
+    };
+
+    // The boundary itself: max - 1 is the last legal point, max is one past it.
+    EXPECT_FALSE(violation("layout(binding = 35) buffer Buffer { int x; };\n").has_value());
+    EXPECT_TRUE(violation("layout(binding = 36) buffer Buffer { int x; };\n").has_value());
+
+    // An instance array takes CONSECUTIVE points, so what has to fit is base + count - 1.
+    EXPECT_FALSE(violation("layout(binding = 32) buffer Buffer { int x; } g_array[4];\n").has_value());
+    EXPECT_TRUE(violation("layout(binding = 34) buffer Buffer { int x; } g_array[4];\n").has_value());
+
+    // Qualifiers and a second layout list may sit between the binding and the keyword.
+    EXPECT_TRUE(violation("layout(std430) layout(binding = 36) coherent restrict buffer B { int x; };\n")
+                    .has_value());
+
+    // Things the scanner must NOT judge: a uniform block (a different ceiling), a storage block
+    // with no explicit binding, the bare default-qualifier form, and an instance array whose size
+    // is not a literal.
+    EXPECT_FALSE(violation("layout(binding = 40) uniform Block { int x; };\n"
+                           "layout(binding = 0) buffer Buffer { int y; };\n")
+                     .has_value());
+    EXPECT_FALSE(violation("buffer Buffer { int x; };\nconst int binding = 40;\n").has_value());
+    EXPECT_FALSE(violation("layout(binding = 1) buffer;\nbuffer Buffer { int x; };\n").has_value());
+    EXPECT_FALSE(violation("const int kCount = 4;\nlayout(binding = 34) buffer B { int x; } g[kCount];\n")
+                     .has_value());
+
+    // A backend that advertises no binding points has no ceiling to enforce.
+    EXPECT_FALSE(FindShaderStorageBindingViolation("layout(binding = 36) buffer B { int x; };\n", 0).has_value());
+}
+
+// KHR-GL43.explicit_uniform_location.uniform-loc-nondecimal: GLSL integer literals are C-style, so
+// layout(location = 0xA) is 10 and layout(location = 010) is OCTAL 8. The extractor used to accept
+// a base-10 digit run and nothing else: the hex spelling failed the test entirely and the
+// declaration silently lost its explicit location, while the octal one was read as decimal 10.
+// The identical defect sat on every array dimension and on layout(binding = N).
+TEST_F(ProgramUtilTest, ExtractExplicitUniformLocationsReadsNonDecimalIntegerLiterals) {
+    using namespace MG_Util::ShaderTranspiler;
+
+    const String source = R"(#version 430 core
+layout(location = 0xA) uniform vec4 hexLower;
+layout(location = 0X1f) uniform vec4 hexUpper;
+layout(location = 010) uniform vec4 octal;
+layout(location = 3u) uniform vec4 unsignedSuffix;
+layout(location = 0x2) uniform float hexArray[0x3];
+layout(location = 1.0) uniform vec4 notAnInteger;
+layout(location = 7f) uniform vec4 unknownSuffix;
+void main() {}
+)";
+
+    const UnorderedMap<String, Int> locations = ExtractExplicitUniformLocations(source);
+    ASSERT_EQ(locations.count("hexLower"), 1u);
+    EXPECT_EQ(locations.at("hexLower"), 10);
+    ASSERT_EQ(locations.count("hexUpper"), 1u);
+    EXPECT_EQ(locations.at("hexUpper"), 31);
+    ASSERT_EQ(locations.count("octal"), 1u);
+    EXPECT_EQ(locations.at("octal"), 8) << "a leading zero is octal in GLSL, not decimal";
+    ASSERT_EQ(locations.count("unsignedSuffix"), 1u);
+    EXPECT_EQ(locations.at("unsignedSuffix"), 3);
+    ASSERT_EQ(locations.count("hexArray"), 1u);
+    EXPECT_EQ(locations.at("hexArray"), 2);
+
+    // Still never guessed at: a float and an unknown suffix are skipped, not rounded.
+    EXPECT_EQ(locations.count("notAnInteger"), 0u);
+    EXPECT_EQ(locations.count("unknownSuffix"), 0u);
+}
+
+// A hexadecimal array dimension has to size the declarator's span too, or the declarator after it
+// in the same statement starts at the wrong location.
+TEST_F(ProgramUtilTest, ExtractExplicitUniformLocationsSpansANonDecimalArrayDimension) {
+    using namespace MG_Util::ShaderTranspiler;
+
+    const UnorderedMap<String, Int> locations = ExtractExplicitUniformLocations(
+        "#version 430 core\nlayout(location = 50) uniform float first[0x3], second;\nvoid main() {}\n");
+    ASSERT_EQ(locations.count("first"), 1u);
+    EXPECT_EQ(locations.at("first"), 50);
+    ASSERT_EQ(locations.count("second"), 1u);
+    EXPECT_EQ(locations.at("second"), 53) << "0x3 is three elements, not zero and not three hundred";
+}
+
+// KHR-GL43.explicit_uniform_location.uniform-loc-array-of-arrays: glslang reflects
+// `float u[2][3]` as "u[0][0]" and "u[1][0]", and the linker resolves such a name by stripping the
+// single trailing "[0]" - so the map has to answer "u[1]", not just "u". Without the pre-flattened
+// keys both records missed the map entirely and were first-fitted from location 0.
+TEST_F(ProgramUtilTest, ExtractExplicitUniformLocationsExpandsArrayOfArraysElements) {
+    using namespace MG_Util::ShaderTranspiler;
+
+    const String source = R"(#version 430 core
+layout(location = 2) uniform float two_d[2][3];
+layout(location = 20) uniform float three_d[2][2][4];
+layout(location = 40) uniform float one_d[3];
+void main() {}
+)";
+
+    const UnorderedMap<String, Int> locations = ExtractExplicitUniformLocations(source);
+
+    // The root entry is unchanged - the synthesized keys are additional, never a replacement.
+    ASSERT_EQ(locations.count("two_d"), 1u);
+    EXPECT_EQ(locations.at("two_d"), 2);
+    // One key per outer index, each starting a run of the innermost dimension (3 here).
+    ASSERT_EQ(locations.count("two_d[0]"), 1u);
+    EXPECT_EQ(locations.at("two_d[0]"), 2);
+    ASSERT_EQ(locations.count("two_d[1]"), 1u);
+    EXPECT_EQ(locations.at("two_d[1]"), 5);
+
+    // Three dimensions: glslang expands all but the innermost, so both outer indices are spelled.
+    ASSERT_EQ(locations.count("three_d"), 1u);
+    EXPECT_EQ(locations.at("three_d"), 20);
+    ASSERT_EQ(locations.count("three_d[0][0]"), 1u);
+    EXPECT_EQ(locations.at("three_d[0][0]"), 20);
+    ASSERT_EQ(locations.count("three_d[0][1]"), 1u);
+    EXPECT_EQ(locations.at("three_d[0][1]"), 24);
+    ASSERT_EQ(locations.count("three_d[1][0]"), 1u);
+    EXPECT_EQ(locations.at("three_d[1][0]"), 28);
+    ASSERT_EQ(locations.count("three_d[1][1]"), 1u);
+    EXPECT_EQ(locations.at("three_d[1][1]"), 32);
+
+    // A 1-D array needs no expansion: stripping "[0]" already reaches the root.
+    ASSERT_EQ(locations.count("one_d"), 1u);
+    EXPECT_EQ(locations.at("one_d"), 40);
+    EXPECT_EQ(locations.count("one_d[0]"), 0u);
+
+    // The declarator after an array-of-arrays still advances by the WHOLE element count.
+    const UnorderedMap<String, Int> pair = ExtractExplicitUniformLocations(
+        "#version 430 core\nlayout(location = 0) uniform float a[2][3], b;\nvoid main() {}\n");
+    ASSERT_EQ(pair.count("b"), 1u);
+    EXPECT_EQ(pair.at("b"), 6);
+}
+
+// KHR-GL43.explicit_uniform_location: layout(binding = 0x2) on a sampler is the same literal defect
+// as the location one, and losing it costs the sampler its initial texture unit.
+TEST_F(ProgramUtilTest, ExtractExplicitOpaqueBindingsReadsNonDecimalIntegerLiterals) {
+    using namespace MG_Util::ShaderTranspiler;
+
+    const String source = R"(#version 430 core
+layout(binding = 0x2) uniform sampler2D hexUnit;
+layout(binding = 012) uniform sampler2D octalUnit;
+layout(binding = 1u) uniform sampler2D suffixedUnit;
+void main() {}
+)";
+
+    const UnorderedMap<String, Uint> bindings = ExtractExplicitOpaqueBindings(source);
+    ASSERT_EQ(bindings.count("hexUnit"), 1u);
+    EXPECT_EQ(bindings.at("hexUnit"), 2u);
+    ASSERT_EQ(bindings.count("octalUnit"), 1u);
+    EXPECT_EQ(bindings.at("octalUnit"), 10u) << "012 is octal ten, not twelve";
+    ASSERT_EQ(bindings.count("suffixedUnit"), 1u);
+    EXPECT_EQ(bindings.at("suffixedUnit"), 1u);
+}

MobileGL/MG_Test/Query/QueryTest.cpp

@@ -19,6 +19,7 @@
 #include <MG_Backend/BackendObjects.h>
 #include <MG_Impl/GLImpl/Getter/GL_Getter.h>
 #include <MG_Impl/GLImpl/Query/GL_Query.h>
+#include <MG_State/GLState/Core.h>
 
 using namespace MobileGL;
 
@@ -119,6 +120,79 @@ namespace {
         g_stubResultObtainable = true;
         g_stubResultNs = 0;
     }
+
+    // Stub backend transform feedback primitive queries. g_stubXfbQuerySupported = false
+    // models a backend with no GPU counter at all (null handle), which is what leaves the
+    // frontend's CPU accounting as the only source; g_stubResultNs is what the "driver"
+    // would answer when its query IS read, deliberately set to a value the CPU accounting
+    // never produces so the two sources are told apart.
+    Int g_stubXfbBeginCount = 0;
+    Int g_stubXfbEndCount = 0;
+    Bool g_stubXfbQuerySupported = true;
+
+    MG_Backend::BackendQueryHandle StubBeginXfbPrimitivesQuery(Bool) {
+        if (!g_stubXfbQuerySupported) {
+            return nullptr;
+        }
+        ++g_stubXfbBeginCount;
+        return reinterpret_cast<MG_Backend::BackendQueryHandle>(static_cast<uintptr_t>(0x53));
+    }
+
+    void StubEndXfbPrimitivesQuery(MG_Backend::BackendQueryHandle) { ++g_stubXfbEndCount; }
+
+    // Stub backend occlusion queries. The host has no ES context, and BeginQuery refuses the
+    // occlusion targets outright when the backend advertises no hook - so a conditional-render
+    // test cannot get a legal predicate object without these. g_stubResultNs is the sample count
+    // the "driver" reports, which is the whole input to the predicate.
+    MG_Backend::BackendQueryHandle StubBeginOcclusionQuery() {
+        return reinterpret_cast<MG_Backend::BackendQueryHandle>(static_cast<uintptr_t>(0x54));
+    }
+
+    void StubEndOcclusionQuery(MG_Backend::BackendQueryHandle) {}
+
+    void InstallStubBackendOcclusionQueries() {
+        auto& backendGL = MG_Backend::gBackendFunctionsTable.GL;
+        backendGL.BeginOcclusionQuery = StubBeginOcclusionQuery;
+        backendGL.EndOcclusionQuery = StubEndOcclusionQuery;
+        backendGL.IsQueryResultAvailable = StubIsQueryResultAvailable;
+        backendGL.GetQueryResult64 = StubGetQueryResult64;
+        backendGL.DeleteBackendQuery = StubDeleteBackendQuery;
+        g_stubDeleteCount = 0;
+        g_stubResultAvailable = true;
+        g_stubResultObtainable = true;
+        g_stubResultNs = 0;
+    }
+
+    void InstallStubBackendXfbQueries() {
+        auto& backendGL = MG_Backend::gBackendFunctionsTable.GL;
+        backendGL.BeginXfbPrimitivesQuery = StubBeginXfbPrimitivesQuery;
+        backendGL.EndXfbPrimitivesQuery = StubEndXfbPrimitivesQuery;
+        backendGL.IsQueryResultAvailable = StubIsQueryResultAvailable;
+        backendGL.GetQueryResult64 = StubGetQueryResult64;
+        backendGL.DeleteBackendQuery = StubDeleteBackendQuery;
+        // Off by default: the tests that exercise the DirectGLES preference turn it on.
+        backendGL.PrefersCpuXfbPrimitiveAccounting = false;
+        g_stubXfbBeginCount = 0;
+        g_stubXfbEndCount = 0;
+        g_stubXfbQuerySupported = true;
+        g_stubDeleteCount = 0;
+        g_stubResultAvailable = true;
+        g_stubResultObtainable = true;
+        g_stubResultNs = 0;
+    }
+
+    // What AccountTransformFeedbackPrimitives (GL_Drawing.cpp) records for one captured
+    // draw, without needing a draw: `assembled` primitives came out of the vertex stage
+    // and `written` of them fitted in the capture buffers (they differ once the buffers
+    // overflow, which is the whole point of PRIMITIVES_WRITTEN).
+    void SimulateAccountedCaptureDraw(Uint64 assembled, Uint64 written, Bool throughGeometryStage = false) {
+        MG_State::pGLContext->AddTransformFeedbackInputPrimitives(assembled);
+        if (throughGeometryStage) {
+            MG_State::pGLContext->AddTransformFeedbackGeometryCaptureDraw();
+        }
+        MG_State::pGLContext->AddTransformFeedbackPrimitives(written);
+        MG_State::pGLContext->AddTransformFeedbackAccountedCaptureDraw();
+    }
 } // namespace
 
 class QueryTest : public ::testing::Test {
@@ -448,12 +522,286 @@ TEST_F(QueryTest, BackendResultsPropagateThroughFrontend) {
     EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
 }
 
+// The two transform feedback targets count different things and must therefore read
+// different counters: PRIMITIVES_WRITTEN what the capture buffers took, PRIMITIVES_GENERATED
+// every primitive the capture stage assembled - including the ones a paused span threw away,
+// which are generated but never written. Answering both from the written counter (as the
+// fallback used to) reports the clamped number as the generated one.
+TEST_F(QueryTest, TransformFeedbackQueryTargetsReadTheirOwnCounter) {
+    const ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendXfbQueries();
+    g_stubXfbQuerySupported = false; // no GPU counter: the CPU accounting is the only source
+
+    GLuint ids[2] = {0, 0};
+    MG_Impl::GLImpl::GenQueries(2, ids);
+    ASSERT_NE(ids[0], 0u);
+    ASSERT_NE(ids[1], 0u);
+
+    MG_Impl::GLImpl::BeginQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, ids[0]);
+    MG_Impl::GLImpl::BeginQuery(GL_PRIMITIVES_GENERATED, ids[1]);
+    // Four points assembled into a buffer with room for three.
+    SimulateAccountedCaptureDraw(/*assembled=*/4, /*written=*/3);
+    // ...and two more points assembled while the span was paused: generated, never written.
+    MG_State::pGLContext->AddTransformFeedbackPausedPrimitives(2);
+    MG_Impl::GLImpl::EndQuery(GL_PRIMITIVES_GENERATED);
+    MG_Impl::GLImpl::EndQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN);
+
+    GLuint written = 0;
+    GLuint generated = 0;
+    MG_Impl::GLImpl::GetQueryObjectuiv(ids[0], GL_QUERY_RESULT, &written);
+    MG_Impl::GLImpl::GetQueryObjectuiv(ids[1], GL_QUERY_RESULT, &generated);
+    EXPECT_EQ(written, 3u);
+    EXPECT_EQ(generated, 6u);
+
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::DeleteQueries(2, ids);
+}
+
+// A query span that captured nothing at all reads zero from the CPU accounting rather than
+// the unsigned wrap-around a bare End-minus-Begin subtraction produces the moment the
+// snapshot is not below the counter (GetQueryObjectuiv would hand the app 4294967295).
+TEST_F(QueryTest, AnEmptyTransformFeedbackSpanReadsZero) {
+    const ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendXfbQueries();
+    g_stubXfbQuerySupported = false;
+
+    GLuint id = 0;
+    MG_Impl::GLImpl::GenQueries(1, &id);
+    ASSERT_NE(id, 0u);
+
+    MG_Impl::GLImpl::BeginQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, id);
+    MG_Impl::GLImpl::EndQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN);
+
+    GLuint result = 123u;
+    MG_Impl::GLImpl::GetQueryObjectuiv(id, GL_QUERY_RESULT, &result);
+    EXPECT_EQ(result, 0u);
+
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::DeleteQueries(1, &id);
+}
+
+// The DirectGLES preference: for a capture the frontend counted exactly - every draw
+// accounted, none of them amplified by a geometry stage - the CPU number is the
+// desktop-exact one and the ES driver's PRIMITIVES_WRITTEN counter is not consulted, even
+// though the backend query ran. The backend query object is released at EndQuery instead of
+// being left to a result read that will never come.
+TEST_F(QueryTest, VertexOnlyCaptureSpansPreferTheCpuPrimitiveAccounting) {
+    const ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendXfbQueries();
+    MG_Backend::gBackendFunctionsTable.GL.PrefersCpuXfbPrimitiveAccounting = true;
+    g_stubResultNs = 6; // what the driver's counter would have said - twice the truth
+
+    GLuint id = 0;
+    MG_Impl::GLImpl::GenQueries(1, &id);
+    ASSERT_NE(id, 0u);
+
+    MG_Impl::GLImpl::BeginQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, id);
+    SimulateAccountedCaptureDraw(/*assembled=*/4, /*written=*/3);
+    MG_Impl::GLImpl::EndQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN);
+    EXPECT_EQ(g_stubXfbBeginCount, 1);
+    EXPECT_EQ(g_stubXfbEndCount, 1);
+    EXPECT_EQ(g_stubDeleteCount, 1); // ended, then released - not leaked
+
+    GLint available = -1;
+    MG_Impl::GLImpl::GetQueryObjectiv(id, GL_QUERY_RESULT_AVAILABLE, &available);
+    EXPECT_EQ(available, 1);
+
+    GLuint result = 0;
+    MG_Impl::GLImpl::GetQueryObjectuiv(id, GL_QUERY_RESULT, &result);
+    EXPECT_EQ(result, 3u);
+    EXPECT_EQ(g_stubDeleteCount, 1); // the read had no handle left to release
+
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::DeleteQueries(1, &id);
+    EXPECT_EQ(g_stubDeleteCount, 1);
+}
+
+// The regression gate for that preference: a capture fed by a geometry stage writes whatever
+// the shader emits, which the CPU accounting cannot model, so the backend's counter stays the
+// answer and its handle survives EndQuery to be read later.
+TEST_F(QueryTest, AGeometryStageCaptureKeepsTheBackendPrimitiveResult) {
+    const ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendXfbQueries();
+    MG_Backend::gBackendFunctionsTable.GL.PrefersCpuXfbPrimitiveAccounting = true;
+    g_stubResultNs = 9; // the amplified count only the driver knows
+
+    GLuint id = 0;
+    MG_Impl::GLImpl::GenQueries(1, &id);
+    ASSERT_NE(id, 0u);
+
+    MG_Impl::GLImpl::BeginQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, id);
+    SimulateAccountedCaptureDraw(/*assembled=*/1, /*written=*/1, /*throughGeometryStage=*/true);
+    MG_Impl::GLImpl::EndQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN);
+    EXPECT_EQ(g_stubDeleteCount, 0); // still to be read
+
+    GLuint result = 0;
+    MG_Impl::GLImpl::GetQueryObjectuiv(id, GL_QUERY_RESULT, &result);
+    EXPECT_EQ(result, 9u);
+    EXPECT_EQ(g_stubDeleteCount, 1);
+
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::DeleteQueries(1, &id);
+}
+
+// The other half of that gate: the instanced, indirect and multi-draw entry points never
+// reach the CPU accounting, so a span made of those moves no counter at all. Its delta would
+// be zero, which is not "nothing was written" - it is "nothing was counted" - and the
+// backend's result has to stand.
+TEST_F(QueryTest, ACaptureSpanTheAccountingNeverSawKeepsTheBackendResult) {
+    const ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendXfbQueries();
+    MG_Backend::gBackendFunctionsTable.GL.PrefersCpuXfbPrimitiveAccounting = true;
+    g_stubResultNs = 12;
+
+    GLuint id = 0;
+    MG_Impl::GLImpl::GenQueries(1, &id);
+    ASSERT_NE(id, 0u);
+
+    MG_Impl::GLImpl::BeginQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN, id);
+    MG_Impl::GLImpl::EndQuery(GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN);
+
+    GLuint result = 0;
+    MG_Impl::GLImpl::GetQueryObjectuiv(id, GL_QUERY_RESULT, &result);
+    EXPECT_EQ(result, 12u);
+
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::DeleteQueries(1, &id);
+}
+
+// GL_PRIMITIVES_GENERATED counts primitives whether or not a capture is active, while the
+// CPU accounting only ever sees capture draws - so the preference above deliberately does
+// not extend to that target, whatever the backend asked for.
+TEST_F(QueryTest, PrimitivesGeneratedKeepsTheBackendResultUnderTheCpuPreference) {
+    const ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendXfbQueries();
+    MG_Backend::gBackendFunctionsTable.GL.PrefersCpuXfbPrimitiveAccounting = true;
+    g_stubResultNs = 7;
+
+    GLuint id = 0;
+    MG_Impl::GLImpl::GenQueries(1, &id);
+    ASSERT_NE(id, 0u);
+
+    MG_Impl::GLImpl::BeginQuery(GL_PRIMITIVES_GENERATED, id);
+    SimulateAccountedCaptureDraw(/*assembled=*/4, /*written=*/3);
+    MG_Impl::GLImpl::EndQuery(GL_PRIMITIVES_GENERATED);
+    EXPECT_EQ(g_stubDeleteCount, 0);
+
+    GLuint result = 0;
+    MG_Impl::GLImpl::GetQueryObjectuiv(id, GL_QUERY_RESULT, &result);
+    EXPECT_EQ(result, 7u);
+
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::DeleteQueries(1, &id);
+}
+
 // Environment-agnostic property test for the env -> ConfigLoader -> Features
 // chain: whatever MOBILEGL_DISABLE_TIMERQUERY is set to in the environment of
 // this test process, MG_ConfigLoader::Init must have parsed it with the
 // unified truthy rule (set, non-empty, not "0", case-insensitive not "false").
 // Running the binary under MOBILEGL_DISABLE_TIMERQUERY=1 therefore exercises
 // the real end-to-end path rather than the struct field alone.
+// KHR-GL43.compute_shader.conditional-dispatching and the conditional_render family.
+// glBeginConditionalRender/glEndConditionalRender were bare stubs: every command inside a
+// conditional block executed whatever the query said, so the block that should have been
+// discarded ran and doubled the atomic counter the case reads back.
+TEST_F(QueryTest, ConditionalRenderResolvesItsPredicateFromTheOcclusionQuery) {
+    ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendOcclusionQueries();
+
+    GLuint ids[2] = {0, 0};
+    MG_Impl::GLImpl::GenQueries(2, ids);
+    ASSERT_NE(ids[0], 0u);
+    ASSERT_NE(ids[1], 0u);
+
+    // One span that saw samples and one that saw none, which is exactly the pair the
+    // conformance case builds out of a passing and a failing depth test.
+    g_stubResultNs = 1;
+    MG_Impl::GLImpl::BeginQuery(GL_ANY_SAMPLES_PASSED, ids[0]);
+    MG_Impl::GLImpl::EndQuery(GL_ANY_SAMPLES_PASSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    GLuint passedResult = 0xFFFFFFFFu;
+    MG_Impl::GLImpl::GetQueryObjectuiv(ids[0], GL_QUERY_RESULT, &passedResult);
+    ASSERT_EQ(passedResult, 1u);
+
+    g_stubResultNs = 0;
+    MG_Impl::GLImpl::BeginQuery(GL_ANY_SAMPLES_PASSED, ids[1]);
+    MG_Impl::GLImpl::EndQuery(GL_ANY_SAMPLES_PASSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // A block on the query that passed executes.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    EXPECT_TRUE(MG_State::pGLContext->IsConditionalRenderActive());
+    EXPECT_FALSE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_FALSE(MG_State::pGLContext->IsConditionalRenderActive());
+    EXPECT_FALSE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+
+    // A block on the query that did not passes nothing through.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[1], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    EXPECT_TRUE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+
+    // ...and the _INVERTED modes swap both verdicts.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT_INVERTED);
+    EXPECT_TRUE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+    MG_Impl::GLImpl::BeginConditionalRender(ids[1], GL_QUERY_BY_REGION_NO_WAIT_INVERTED);
+    EXPECT_FALSE(MG_State::pGLContext->ConditionalRenderDiscardsCommands());
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::DeleteQueries(2, ids);
+}
+
+TEST_F(QueryTest, ConditionalRenderRejectsTheErrorsTheSpecNames) {
+    ScopedBackendFunctionsOverride backendGuard;
+    InstallStubBackendOcclusionQueries();
+
+    GLuint ids[2] = {0, 0};
+    MG_Impl::GLImpl::GenQueries(2, ids);
+    g_stubResultNs = 1;
+    MG_Impl::GLImpl::BeginQuery(GL_ANY_SAMPLES_PASSED, ids[0]);
+    MG_Impl::GLImpl::EndQuery(GL_ANY_SAMPLES_PASSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // GL 4.6 core 10.9, one rule at a time.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_TIME_ELAPSED);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_ENUM);
+    EXPECT_FALSE(MG_State::pGLContext->IsConditionalRenderActive());
+
+    // A generated NAME is not yet a query object.
+    MG_Impl::GLImpl::BeginConditionalRender(ids[1], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_VALUE);
+    MG_Impl::GLImpl::BeginConditionalRender(0, GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_VALUE);
+
+    // A query that is not an occlusion query cannot drive one.
+    GLuint timerId = 0;
+    MG_Impl::GLImpl::GenQueries(1, &timerId);
+    MG_Impl::GLImpl::BeginQuery(GL_TIME_ELAPSED, timerId);
+    MG_Impl::GLImpl::EndQuery(GL_TIME_ELAPSED);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::BeginConditionalRender(timerId, GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_OPERATION);
+
+    // End without a block, and a nested Begin.
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_OPERATION);
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::BeginConditionalRender(ids[0], GL_QUERY_WAIT);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_INVALID_OPERATION);
+    // The rejected nested Begin must not have disturbed the open block.
+    EXPECT_EQ(MG_State::pGLContext->GetConditionalRenderQuery(), ids[0]);
+    MG_Impl::GLImpl::EndConditionalRender();
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::DeleteQueries(2, ids);
+    MG_Impl::GLImpl::DeleteQueries(1, &timerId);
+}
+
 TEST_F(QueryTest, DisableTimerQueryFeatureMatchesEnvironment) {
     const char* raw = std::getenv("MOBILEGL_DISABLE_TIMERQUERY");
     Bool expected = false;

MobileGL/MG_Test/SanityTest.cpp

@@ -17,6 +17,7 @@
 #include <MG_Backend/DirectGLES/Managers.h>
 #include <MG_Backend/DirectVulkan/BackendObject_DirectVulkan.h>
 #include <MG_Backend/BackendObjects.h>
+#include <MG_Impl/GLImpl/Buffer/GL_Buffer.h>
 #include <MG_Impl/GLImpl/Getter/GL_Getter.h>
 #include <MG_Impl/GLImpl/RenderState/GL_RenderState.h>
 #include <MG_Impl/GLImpl/Texture/GL_Texture.h>
@@ -365,6 +366,13 @@ TEST(DirectGLESSanity, RebasesInstanceIdWhenIndirectDrawsLeakBaseInstance) {
     // MaxShaderStorageBufferBindings - 1 = 12, so a regression that stops reading the
     // probed cap and falls back to the struct default would surface as "binding = 7".
     caps.MaxShaderStorageBufferBindings = 13;
+    // The indirect lowering reads its baseInstance through a storage block declared in the
+    // VERTEX stage, which is optional in both APIs and which the GLESCapabilities default
+    // (0, the spec minimum) therefore denies. This suite is pinning the shape of that
+    // lowering, so it has to describe a driver that can actually have it - see
+    // VertexStageStorageBlockUsable and the BaseInstanceInjectionGate suite for the
+    // zero case.
+    caps.MaxVertexShaderStorageBlocks = 1;
 
     const MobileGL::String source = R"(#version 310 es
 highp int mg_BaseInstanceLowered;
@@ -403,6 +411,9 @@ TEST(DirectGLESSanity, TheIndirectWordIndexIsOneBasedSoItsUnwrittenValueMeansNot
     auto& caps = MobileGL::MG_Backend::DirectGLES::g_GLESCapabilities;
     caps.IndirectDrawInstanceIdIncludesBaseInstance = false;
     caps.MaxShaderStorageBufferBindings = 13;
+    // See RebasesInstanceIdWhenIndirectDrawsLeakBaseInstance: without a vertex-stage
+    // storage block there is no word index to be one-based about.
+    caps.MaxVertexShaderStorageBlocks = 1;
 
     const MobileGL::String source = R"(#version 310 es
 highp int mg_BaseInstanceLowered;
@@ -428,6 +439,10 @@ TEST(DirectGLESSanity, KeepsInstanceIdWhenIndirectDrawsAreConforming) {
     auto& caps = MobileGL::MG_Backend::DirectGLES::g_GLESCapabilities;
     caps.IndirectDrawInstanceIdIncludesBaseInstance = false;
     caps.MaxShaderStorageBufferBindings = 13;
+    // Set explicitly even though the assertions below would also hold on the degraded path:
+    // this case is about a CONFORMING driver leaving gl_InstanceID alone, and it would be a
+    // silent weakening for it to be exercising the no-storage-block fallback instead.
+    caps.MaxVertexShaderStorageBlocks = 1;
 
     const MobileGL::String source = R"(#version 310 es
 highp int mg_BaseInstanceLowered;
@@ -442,6 +457,8 @@ void main() {
 
     EXPECT_EQ(rewritten.find("mg_ZeroBasedInstanceID"), MobileGL::String::npos);
     EXPECT_NE(rewritten.find("int instance = gl_InstanceID + mg_BaseInstanceLowered;"), MobileGL::String::npos);
+    // The indirect view is present on this driver, so the fallback must NOT have fired.
+    EXPECT_NE(rewritten.find("buffer mg_IndirectParams"), MobileGL::String::npos);
 }
 
 TEST(DirectGLESSanity, LeavesDrawParameterGlobalsAloneOutsideVertexShaders) {
@@ -626,6 +643,55 @@ TEST(DirectGLESSanity, PreservesHostPerStageImageUniformLimits) {
     EXPECT_EQ(params.MaxComputeImageUniforms, 5);
 }
 
+// maxClipDistances is a LIMIT every Vulkan device reports; declaring ClipDistance in a module
+// needs the shaderClipDistance FEATURE, which is separate and which VulkanRenderer enables only
+// where the physical device has it. Forwarding the limit without the feature advertises eight
+// clip planes no shader may use - the same shape as the image-uniform limits above, and the same
+// shape as the GL_EXT_clip_cull_distance lie on DirectGLES. Not a blanket zero: a device WITH the
+// feature keeps its real number.
+TEST(DirectVulkanSanity, GatesClipDistancesOnTheShaderClipDistanceFeature) {
+    using namespace MobileGL;
+
+    MG_Backend::DirectVulkan::BackendObject_DirectVulkan backend;
+    MG_External::VulkanCapabilities caps;
+    caps.MaxClipDistances = 8;
+
+    caps.SupportsShaderClipDistance = false;
+    backend.ApplyVulkanCapabilitiesForTesting(caps);
+    EXPECT_EQ(backend.GetDynamicParameters().MaxClipDistances, 0);
+
+    caps.SupportsShaderClipDistance = true;
+    backend.ApplyVulkanCapabilitiesForTesting(caps);
+    EXPECT_EQ(backend.GetDynamicParameters().MaxClipDistances, 8);
+}
+
+// GL_LAYER_PROVOKING_VERTEX / GL_VIEWPORT_INDEX_PROVOKING_VERTEX were a hard-coded
+// GL_LAST_VERTEX_CONVENTION for both backends, derived from nothing, and wrong on both test
+// devices in opposite directions. DirectGLES now forwards what its loader resolved; DirectVulkan
+// reports GL_UNDEFINED_VERTEX, which GL 4.6 table 23.65 permits and which is what the backend
+// honestly implements - the provoking mode is chosen per pipeline out of VK_EXT_provoking_vertex,
+// provokingVertexModePerPipeline and the topology.
+TEST(ProvokingVertexConventions, EachBackendReportsWhatItActuallyPins) {
+    using namespace MobileGL;
+
+    MG_Backend::DirectGLES::BackendObject_DirectGLES glesBackend;
+    MG_External::GLESCapabilities glesCaps;
+    glesCaps.LayerProvokingVertex = GL_FIRST_VERTEX_CONVENTION;
+    glesCaps.ViewportIndexProvokingVertex = GL_UNDEFINED_VERTEX;
+    glesBackend.ApplyGLESCapabilitiesForTesting(glesCaps);
+    EXPECT_EQ(glesBackend.GetDynamicParameters().LayerProvokingVertex,
+              static_cast<GLenum>(GL_FIRST_VERTEX_CONVENTION));
+    EXPECT_EQ(glesBackend.GetDynamicParameters().ViewportIndexProvokingVertex,
+              static_cast<GLenum>(GL_UNDEFINED_VERTEX));
+
+    MG_Backend::DirectVulkan::BackendObject_DirectVulkan vkBackend;
+    MG_External::VulkanCapabilities vkCaps;
+    vkBackend.ApplyVulkanCapabilitiesForTesting(vkCaps);
+    EXPECT_EQ(vkBackend.GetDynamicParameters().LayerProvokingVertex, static_cast<GLenum>(GL_UNDEFINED_VERTEX));
+    EXPECT_EQ(vkBackend.GetDynamicParameters().ViewportIndexProvokingVertex,
+              static_cast<GLenum>(GL_UNDEFINED_VERTEX));
+}
+
 TEST(FragmentInterpolationCapabilities, PlumbsGLESAndBothVulkanPropertyPaths) {
     using namespace MobileGL;
 
@@ -913,6 +979,161 @@ void main() {
     MG_Backend::pActiveBackendObject.reset();
 }
 
+// KHR-GL43.shader_atomic_counters.basic-glsl-built-in, .basic-buffer-bind and .basic-api-get.
+// The atomic-counter limits used to live in two unreconciled tables - glslang compiled every
+// shader against ONE binding while glGetIntegerv advertised thirty-six - and three of the enums
+// had no case in the getter at all, so the query raised INVALID_ENUM and left the caller reading
+// whatever was in its own stack slot.
+TEST(GetterSanity, AtomicCounterQueriesMatchShaderCompilerLimits) {
+    using namespace MobileGL;
+    namespace Transpiler = MG_Util::ShaderTranspiler;
+
+    auto previousContext = Move(MG_State::pGLContext);
+    auto previousBackend = Move(MG_Backend::pActiveBackendObject);
+    MG_State::pGLContext = MakeUnique<MG_State::GLState::GLContext>();
+    MG_Backend::pActiveBackendObject = MakeUnique<DynamicParameterBackend>(MG_Backend::DynamicBackendParameters{});
+
+    GLint reported = -1;
+    MG_Impl::GLImpl::GetIntegerv(GL_MAX_ATOMIC_COUNTER_BUFFER_BINDINGS, &reported);
+    EXPECT_EQ(reported, static_cast<GLint>(Transpiler::MAX_ATOMIC_COUNTER_BUFFER_BINDINGS));
+    MG_Impl::GLImpl::GetIntegerv(GL_MAX_ATOMIC_COUNTER_BUFFER_SIZE, &reported);
+    EXPECT_EQ(reported, static_cast<GLint>(Transpiler::MAX_ATOMIC_COUNTER_BUFFER_SIZE));
+    for (const GLenum pname : {GL_MAX_COMBINED_ATOMIC_COUNTER_BUFFERS, GL_MAX_FRAGMENT_ATOMIC_COUNTER_BUFFERS,
+                               GL_MAX_COMPUTE_ATOMIC_COUNTER_BUFFERS}) {
+        reported = -1;
+        MG_Impl::GLImpl::GetIntegerv(pname, &reported);
+        EXPECT_EQ(reported, static_cast<GLint>(Transpiler::MAX_ATOMIC_COUNTER_BUFFERS_PER_STAGE))
+            << "pname " << pname;
+    }
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // glBindBufferBase sets the GENERIC binding point too (GL 4.6 6.1.1), and this is the one
+    // indexed-buffer family whose non-indexed query had no case.
+    reported = -1;
+    MG_Impl::GLImpl::GetIntegerv(GL_ATOMIC_COUNTER_BUFFER_BINDING, &reported);
+    EXPECT_EQ(reported, 0);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    GLuint buffer = 0;
+    MG_Impl::GLImpl::GenBuffers(1, &buffer);
+    MG_Impl::GLImpl::BindBuffer(GL_ATOMIC_COUNTER_BUFFER, buffer);
+    MG_Impl::GLImpl::BufferData(GL_ATOMIC_COUNTER_BUFFER, 64, nullptr, GL_STATIC_DRAW);
+    MG_Impl::GLImpl::BindBufferBase(GL_ATOMIC_COUNTER_BUFFER, 2, buffer);
+    MG_Impl::GLImpl::GetIntegerv(GL_ATOMIC_COUNTER_BUFFER_BINDING, &reported);
+    EXPECT_EQ(static_cast<GLuint>(reported), buffer);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // The advertised ceiling is also the one glBindBufferBase and the indexed getter enforce.
+    // A limit nothing validates against is how these tables drifted apart in the first place:
+    // the binding-point ARRAY is 36 deep, and it used to be that number an application saw.
+    constexpr GLuint pastLastBinding = static_cast<GLuint>(Transpiler::MAX_ATOMIC_COUNTER_BUFFER_BINDINGS);
+    MG_Impl::GLImpl::BindBufferBase(GL_ATOMIC_COUNTER_BUFFER, pastLastBinding, buffer);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), static_cast<GLenum>(GL_INVALID_VALUE));
+    MG_Impl::GLImpl::GetIntegeri_v(GL_ATOMIC_COUNTER_BUFFER_BINDING, pastLastBinding, &reported);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), static_cast<GLenum>(GL_INVALID_VALUE));
+
+    // ...and the shading language has to expand the same numbers. Each array is sized by a
+    // built-in constant and indexed at its last element with a literal, so the stage only
+    // compiles when that constant is at least what glGetIntegerv just reported - which it was
+    // not while the resource table said one.
+    const String lastBinding = std::to_string(Transpiler::MAX_ATOMIC_COUNTER_BUFFER_BINDINGS - 1);
+    const String lastBuffer = std::to_string(Transpiler::MAX_ATOMIC_COUNTER_BUFFERS_PER_STAGE - 1);
+    const String source = R"(#version 430 core
+out vec4 color;
+int mgBindings[gl_MaxAtomicCounterBindings];
+int mgCombinedBuffers[gl_MaxCombinedAtomicCounterBuffers];
+int mgFragmentBuffers[gl_MaxFragmentAtomicCounterBuffers];
+layout(binding = )" + lastBinding + R"(, offset = 0) uniform atomic_uint mgCounter;
+void main() {
+    color = vec4(float(mgBindings[)" + lastBinding + R"(] + mgCombinedBuffers[)" + lastBuffer +
+                         R"(] + mgFragmentBuffers[)" + lastBuffer + R"(] + int(atomicCounterIncrement(mgCounter))));
+}
+)";
+    auto compiled = MG_Util::ShaderTranspiler::ShaderCompiler::CompileShader({
+        .shaderType = GL_FRAGMENT_SHADER,
+        .sourceStr = source,
+    });
+    EXPECT_TRUE(compiled) << (compiled ? "" : compiled.error().log);
+
+    MG_Backend::pActiveBackendObject = Move(previousBackend);
+    MG_State::pGLContext = Move(previousContext);
+}
+
+// KHR-GL43.compute_shader.max: the test queries every GL_MAX_COMPUTE_* value through the API and
+// then makes a compute shader compare the matching gl_MaxCompute* constant against it. The two
+// used to be independent tables and gl_MaxComputeWorkGroupSize.z disagreed - glslang compiled
+// against a permissive 1024 while the context advertises the 64 the GL 4.6 minimum (and every ES
+// driver) reports.
+TEST(GetterSanity, ComputeWorkGroupQueriesMatchShaderCompilerLimits) {
+    using namespace MobileGL;
+
+    auto previousContext = Move(MG_State::pGLContext);
+    auto previousBackend = Move(MG_Backend::pActiveBackendObject);
+    MG_State::pGLContext = MakeUnique<MG_State::GLState::GLContext>();
+    MG_Backend::pActiveBackendObject = MakeUnique<DynamicParameterBackend>(MG_Backend::DynamicBackendParameters{});
+
+    GLint size[3] = {0, 0, 0};
+    GLint count[3] = {0, 0, 0};
+    for (GLuint index = 0; index < 3; ++index) {
+        MG_Impl::GLImpl::GetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE, index, &size[index]);
+        MG_Impl::GLImpl::GetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT, index, &count[index]);
+    }
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // The compile runs against a captured env, exactly as the pipeline's does. That is the whole
+    // invariant: the env holds the same floored driver answer GetIntegeri_v just returned, so the
+    // resource table and the query agree BY CONSTRUCTION rather than by two tables happening to
+    // carry the same literals.
+    const auto env = MG_Util::ShaderTranspiler::CaptureCompileEnv();
+    for (GLuint index = 0; index < 3; ++index) {
+        EXPECT_EQ(static_cast<GLint>(env->maxComputeWorkGroupSize[index]), size[index]) << "index " << index;
+        EXPECT_EQ(static_cast<GLint>(env->maxComputeWorkGroupCount[index]), count[index]) << "index " << index;
+    }
+
+    // A negative array size is a compile error, so the stage only compiles when EVERY component
+    // of both built-in constants equals what the query above reported. Two-sided by construction:
+    // a resource table that is too permissive fails it exactly like one that is too tight.
+    const String source = R"(#version 430 core
+layout(local_size_x = 1) in;
+const int mgAgree = (gl_MaxComputeWorkGroupSize == ivec3()" +
+                         std::to_string(size[0]) + ", " + std::to_string(size[1]) + ", " +
+                         std::to_string(size[2]) + R"() &&
+                     gl_MaxComputeWorkGroupCount == ivec3()" +
+                         std::to_string(count[0]) + ", " + std::to_string(count[1]) + ", " +
+                         std::to_string(count[2]) + R"()) ? 1 : -1;
+int mgProbe[mgAgree];
+void main() {
+    mgProbe[0] = 0;
+}
+)";
+    auto compiled = MG_Util::ShaderTranspiler::ShaderCompiler::CompileShader({
+        .shaderType = GL_COMPUTE_SHADER,
+        .sourceStr = source,
+        .env = env.get(),
+    });
+    EXPECT_TRUE(compiled) << (compiled ? "" : compiled.error().log);
+
+    // The z ceiling is also what glslang checks a declared local_size_z against, so it has to
+    // reject one invocation past the advertised limit and accept the limit itself.
+    const String atLimit = "#version 430 core\nlayout(local_size_z = " + std::to_string(size[2]) +
+                           ") in;\nvoid main() {}\n";
+    const String pastLimit = "#version 430 core\nlayout(local_size_z = " + std::to_string(size[2] + 1) +
+                             ") in;\nvoid main() {}\n";
+    EXPECT_TRUE(MG_Util::ShaderTranspiler::ShaderCompiler::CompileShader({
+        .shaderType = GL_COMPUTE_SHADER,
+        .sourceStr = atLimit,
+        .env = env.get(),
+    }));
+    EXPECT_FALSE(MG_Util::ShaderTranspiler::ShaderCompiler::CompileShader({
+        .shaderType = GL_COMPUTE_SHADER,
+        .sourceStr = pastLimit,
+        .env = env.get(),
+    }));
+
+    MG_Backend::pActiveBackendObject = Move(previousBackend);
+    MG_State::pGLContext = Move(previousContext);
+}
+
 TEST(GetterSanity, ReportsKhrSubgroupDynamicParameters) {
     using namespace MobileGL;
 

MobileGL/MG_Test/ShaderTranspiler/CMakeLists.txt

@@ -9,6 +9,9 @@ add_executable(
         EmulateSubgroupsTest.cpp
         DemoteFloat64Test.cpp
         FlattenXfbInterfaceBlocksTest.cpp
+        UniquifyIoBlockNamesTest.cpp
+        LowerViewportIndexTest.cpp
+        ClampMultisampleFetchTest.cpp
 )
 
 target_include_directories(SpirvPassTest PRIVATE
@@ -27,5 +30,33 @@ if (MSVC)
         target_compile_options(SpirvPassTest PRIVATE /Zc:preprocessor)
 endif()
 
+# Its own binary: several cases flip MG_Config::Features.ShaderTranslationCache and
+# MG_Config::Features.AsyncShaderCompile and read the PROCESS-GLOBAL L1 counters straight
+# afterwards, so another suite's links running in the same process would show up as
+# hits/misses this one did not cause.
+add_executable(
+        TranslationCacheTest
+        TranslationCacheTest.cpp
+)
+
+target_include_directories(TranslationCacheTest PRIVATE
+        ${MGL_ROOT}/include
+        ${MGL_ROOT}/MobileGL
+        ${MGL_ROOT}/3rdparty/SPIRV-Reflect
+)
+
+target_link_libraries(
+        TranslationCacheTest PRIVATE
+        GTest::gtest_main
+        ${LINK_LIBRARIES}
+)
+
+if (MSVC)
+        target_compile_options(TranslationCacheTest PRIVATE /Zc:preprocessor)
+endif()
+
 include(GoogleTest)
 gtest_discover_tests(SpirvPassTest DISCOVERY_TIMEOUT 30 PROPERTIES LABELS unit)
+# Heavier than a pure-pass suite: the concurrency cases run 8 threads over thousands of
+# rounds and the end-to-end cases link real programs through the compile pool.
+gtest_discover_tests(TranslationCacheTest DISCOVERY_TIMEOUT 60 PROPERTIES LABELS unit TIMEOUT 300)

MobileGL/MG_Test/ShaderTranspiler/ClampMultisampleFetchTest.cpp

@@ -0,0 +1,383 @@
+// MobileGL - MobileGL/MG_Test/ShaderTranspiler/ClampMultisampleFetchTest.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// ClampMultisampleFetchPass exists because MobileGL advertises one multisample ceiling and the ES
+// driver underneath delivers another. GL 4.6 core table 23.53 forces GL_MAX_SAMPLES and
+// GL_MAX_INTEGER_SAMPLES up to 4; Adreno and Mali back an integer multisample texture with ONE
+// sample, and DirectGLES quietly allocates that (ClampSamplesToBackendSupport). A CTS shader that
+// bakes in `texelFetch(usampler2DMS, coord, 3)` - which is what
+// KHR-GL33/40/41.texture_swizzle.functional_* and KHR-GLxx.texture_size_promotion.functional do -
+// then reads a sample the storage does not have.
+//
+// So what has to hold is per-fetch and per-category at once: the squeezed category's Sample
+// operand must come back in range, a category that is not squeezed must be untouched, a module
+// with no multisampled image at all must come out byte for byte as it went in, and every result
+// must still be a valid module. Real GLSL through the same glslang path the backends use, for the
+// same reason LowerViewportIndexTest.cpp does it: what matters is what glslang actually emits.
+
+#include <gtest/gtest.h>
+
+#define SPV_ENABLE_UTILITY_CODE
+#include "glslang/SPIRV/spirv.hpp11"
+#undef SPV_ENABLE_UTILITY_CODE
+
+#include "Includes.h"
+#include "Init.h"
+#include <MG_Util/ShaderTranspiler/ShaderCompiler.h>
+#include <MG_Util/ShaderTranspiler/Types.h>
+
+#include <spirv-tools/libspirv.hpp>
+
+#include <map>
+#include <string>
+#include <vector>
+
+using namespace MobileGL;
+using MobileGL::MG_Util::ShaderTranspiler::ShaderCompiler;
+
+namespace {
+    // GLSL.std.450 instruction number (see 3rdparty/glslang/SPIRV/GLSL.std.450.h). The signed
+    // minimum, which is what a GLSL `int` sample index asks for.
+    constexpr Uint32 kGlslStd450SMin = 39u;
+
+    // What MobileGL tells the application GL_MAX_SAMPLES / GL_MAX_INTEGER_SAMPLES are, i.e.
+    // GL_Getter's kFrontendMaxSamples floor. Each test supplies its own backend-real ceilings
+    // against it; Adreno and Mali's Immortalis-G925 both really answer 1 for integer formats.
+    constexpr Int32 kAdvertisedMaxSamples = 4;
+
+    constexpr SizeT kSpirvHeaderWordCount = 5u;
+
+    template <typename Visitor>
+    void ForEachInstruction(const Vector<Uint32>& spirv, Visitor&& visit) {
+        for (SizeT offset = kSpirvHeaderWordCount; offset < spirv.size();) {
+            const Uint32 wordCount = spirv[offset] >> 16u;
+            if (wordCount == 0u || offset + wordCount > spirv.size()) break;
+            visit(static_cast<spv::Op>(spirv[offset] & 0xffffu), &spirv[offset], wordCount);
+            offset += wordCount;
+        }
+    }
+
+    Vector<Uint32> CompileFragment(const String& source) {
+        using namespace MobileGL::MG_Util::ShaderTranspiler;
+        ShaderAttrib shaderAttrib{.shaderType = GL_FRAGMENT_SHADER, .sourceStr = source};
+        auto shaderResult = ShaderCompiler::CompileShader(shaderAttrib);
+        EXPECT_TRUE(shaderResult) << (shaderResult ? String{} : shaderResult.error().log);
+        if (!shaderResult) return {};
+
+        ProgramAttrib programAttrib{.shaders = {shaderResult.value()}};
+        auto programResult = ShaderCompiler::LinkProgram(programAttrib);
+        EXPECT_TRUE(programResult) << (programResult ? String{} : programResult.error().log);
+        if (!programResult) return {};
+
+        ProgramBinaryAttrib binaryAttrib{.shaderTypes = {GL_FRAGMENT_SHADER},
+                                         .program = *programResult.value()};
+        auto binaryResult = ShaderCompiler::GetSpirvBinaryFromProgram(binaryAttrib);
+        EXPECT_TRUE(binaryResult) << (binaryResult ? String{} : binaryResult.error().log);
+        if (!binaryResult || binaryResult->empty()) return {};
+        return binaryResult->front();
+    }
+
+    String Disassemble(const Vector<Uint32>& spirv) {
+        spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+        String text;
+        tools.Disassemble(spirv, &text);
+        return text;
+    }
+
+    bool Validates(const Vector<Uint32>& spirv) {
+        spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+        tools.SetMessageConsumer(
+            [](spv_message_level_t, const char*, const spv_position_t& position, const char* message) {
+                ADD_FAILURE() << "spirv-val at word " << position.index << ": " << message;
+            });
+        return tools.Validate(spirv);
+    }
+
+    // OpImageFetch words: 0 opcode/count, 1 result type, 2 result id, 3 image, 4 coordinate,
+    // 5 the optional image-operands mask, 6.. the ids that mask asks for.
+    struct ImageFetch {
+        Uint32 resultId = 0u;
+        Uint32 imageId = 0u;
+        Uint32 mask = 0u;
+        Vector<Uint32> maskOperandIds;
+    };
+
+    Vector<ImageFetch> CollectImageFetches(const Vector<Uint32>& spirv) {
+        Vector<ImageFetch> fetches;
+        ForEachInstruction(spirv, [&](spv::Op opcode, const Uint32* words, Uint32 wordCount) {
+            if (opcode != spv::Op::OpImageFetch || wordCount < 5u) return;
+            ImageFetch fetch{};
+            fetch.resultId = words[2];
+            fetch.imageId = words[3];
+            if (wordCount > 5u) {
+                fetch.mask = words[5];
+                for (Uint32 word = 6u; word < wordCount; ++word) {
+                    fetch.maskOperandIds.push_back(words[word]);
+                }
+            }
+            fetches.push_back(fetch);
+        });
+        return fetches;
+    }
+
+    // OpExtInst words: 0 opcode/count, 1 result type, 2 result id, 3 set, 4 instruction number,
+    // 5.. the operand ids.
+    struct ExtInst {
+        Uint32 resultId = 0u;
+        Uint32 instructionNumber = 0u;
+        Vector<Uint32> operandIds;
+    };
+
+    Vector<ExtInst> CollectExtInsts(const Vector<Uint32>& spirv) {
+        Vector<ExtInst> extInsts;
+        ForEachInstruction(spirv, [&](spv::Op opcode, const Uint32* words, Uint32 wordCount) {
+            if (opcode != spv::Op::OpExtInst || wordCount < 5u) return;
+            ExtInst extInst{};
+            extInst.resultId = words[2];
+            extInst.instructionNumber = words[4];
+            for (Uint32 word = 5u; word < wordCount; ++word) {
+                extInst.operandIds.push_back(words[word]);
+            }
+            extInsts.push_back(extInst);
+        });
+        return extInsts;
+    }
+
+    std::map<Uint32, Uint32> CollectScalarConstants(const Vector<Uint32>& spirv) {
+        std::map<Uint32, Uint32> values;
+        ForEachInstruction(spirv, [&](spv::Op opcode, const Uint32* words, Uint32 wordCount) {
+            if (opcode == spv::Op::OpConstant && wordCount == 4u) values[words[2]] = words[3];
+        });
+        return values;
+    }
+
+    // The one fetch carrying an explicit Sample operand. glslang emits Sample on its own for a
+    // multisample texelFetch - there is no texelFetchOffset for a multisampled sampler - so the
+    // sample id is the mask's first and only operand.
+    const ImageFetch* FindSampleCarryingFetch(const Vector<ImageFetch>& fetches) {
+        for (const ImageFetch& fetch : fetches) {
+            if ((fetch.mask & static_cast<Uint32>(spv::ImageOperandsMask::Sample)) != 0u) {
+                return &fetch;
+            }
+        }
+        return nullptr;
+    }
+
+    const ImageFetch* FindLodCarryingFetch(const Vector<ImageFetch>& fetches) {
+        for (const ImageFetch& fetch : fetches) {
+            if ((fetch.mask & static_cast<Uint32>(spv::ImageOperandsMask::Lod)) != 0u) {
+                return &fetch;
+            }
+        }
+        return nullptr;
+    }
+
+    // KHR-GL4x.texture_swizzle.functional's integer multisample read in miniature: the sample
+    // index is the advertised GL_MAX_INTEGER_SAMPLES - 1, baked in as a literal, which is exactly
+    // the value the one-sample allocation underneath cannot answer. The plain sampler2D fetch is
+    // the negative control - a NON-multisampled image whose Lod operand this pass must not touch.
+    const char* const kIntegerMultisampleFetch = R"(#version 410 core
+uniform usampler2DMS uintMs;
+uniform sampler2D plain;
+out vec4 fragColor;
+void main() {
+    uvec4 texel = texelFetch(uintMs, ivec2(gl_FragCoord.xy), 3);
+    vec4 other = texelFetch(plain, ivec2(gl_FragCoord.xy), 0);
+    fragColor = vec4(texel) * 0.5 + other;
+}
+)";
+
+    // The colour class, which real devices squeeze to something above 1 rather than to 1.
+    const char* const kColorMultisampleFetch = R"(#version 410 core
+uniform sampler2DMS colorMs;
+out vec4 fragColor;
+void main() {
+    fragColor = texelFetch(colorMs, ivec2(gl_FragCoord.xy), 3);
+}
+)";
+
+    // Every stage on a squeezed device goes through the probe, so the one that declares no
+    // multisampled image has to come back untouched.
+    const char* const kNoMultisampleFetch = R"(#version 410 core
+uniform sampler2D plain;
+out vec4 fragColor;
+void main() {
+    fragColor = texelFetch(plain, ivec2(gl_FragCoord.xy), 0);
+}
+)";
+} // namespace
+
+class ClampMultisampleFetchTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        MobileGL::Initialize();
+        m_validationFailuresAtStart = ShaderCompiler::SpirvValidationFailureCount();
+    }
+
+    void TearDown() override {
+        EXPECT_EQ(ShaderCompiler::SpirvValidationFailureCount(), m_validationFailuresAtStart)
+            << "the clamped module did not survive spirv-val";
+    }
+
+    Uint64 m_validationFailuresAtStart = 0;
+};
+
+// The probe is the gate that keeps every ordinary stage off an optimizer round trip, so it has to
+// answer no for a shader that never reads a multisample texture - and yes for the ones that do.
+TEST_F(ClampMultisampleFetchTest, TheProbeAnswersOnlyForAMultisampledImage) {
+    const Vector<Uint32> plain = CompileFragment(kNoMultisampleFetch);
+    ASSERT_FALSE(plain.empty());
+    EXPECT_FALSE(ShaderCompiler::DeclaresMultisampledImage(plain));
+
+    const Vector<Uint32> integerMs = CompileFragment(kIntegerMultisampleFetch);
+    ASSERT_FALSE(integerMs.empty());
+    EXPECT_TRUE(ShaderCompiler::DeclaresMultisampledImage(integerMs));
+
+    const Vector<Uint32> colorMs = CompileFragment(kColorMultisampleFetch);
+    ASSERT_FALSE(colorMs.empty());
+    EXPECT_TRUE(ShaderCompiler::DeclaresMultisampledImage(colorMs));
+
+    // Runs on every stage of every program on a squeezed device, so it must survive a stage that
+    // produced no SPIR-V rather than pushing a parse diagnostic for it.
+    EXPECT_FALSE(ShaderCompiler::DeclaresMultisampledImage({}));
+}
+
+// The combined probe answers both gate questions from one parse; it must agree with the
+// per-gate probes on the same modules and stay quiet for an empty stage.
+TEST_F(ClampMultisampleFetchTest, TheCombinedProbeAgreesWithThePerGateOnes) {
+    const Vector<Uint32> integerMs = CompileFragment(kIntegerMultisampleFetch);
+    ASSERT_FALSE(integerMs.empty());
+    const auto msFeatures = ShaderCompiler::ProbeSpirvGateFeatures(integerMs);
+    EXPECT_TRUE(msFeatures.DeclaresMultisampledImage);
+    EXPECT_FALSE(msFeatures.WritesViewportIndexOutput);
+
+    const Vector<Uint32> plain = CompileFragment(kNoMultisampleFetch);
+    ASSERT_FALSE(plain.empty());
+    const auto plainFeatures = ShaderCompiler::ProbeSpirvGateFeatures(plain);
+    EXPECT_FALSE(plainFeatures.DeclaresMultisampledImage);
+    EXPECT_FALSE(plainFeatures.WritesViewportIndexOutput);
+
+    const auto emptyFeatures = ShaderCompiler::ProbeSpirvGateFeatures({});
+    EXPECT_FALSE(emptyFeatures.DeclaresMultisampledImage);
+    EXPECT_FALSE(emptyFeatures.WritesViewportIndexOutput);
+}
+
+// The overwhelming majority of modules. Behind the probe they never reach the pass at all, but the
+// pass has to be inert for them on its own, or a future caller that forgets the gate silently
+// re-serialises every shader in the program.
+TEST_F(ClampMultisampleFetchTest, LeavesAModuleWithoutAMultisampledImageUntouched) {
+    const Vector<Uint32> input = CompileFragment(kNoMultisampleFetch);
+    ASSERT_FALSE(input.empty());
+
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::ClampMultisampleFetchesForEssl(
+        input, output, /*maxColorSamples=*/4, /*maxIntegerSamples=*/1, /*maxDepthSamples=*/4,
+        kAdvertisedMaxSamples, true));
+    EXPECT_EQ(output, input) << Disassemble(output);
+}
+
+// The bug itself. GL_MAX_INTEGER_SAMPLES says 4, the texture has one sample, and the shader asks
+// for sample 3.
+TEST_F(ClampMultisampleFetchTest, ReplacesAnOutOfRangeIntegerSampleWithZero) {
+    const Vector<Uint32> input = CompileFragment(kIntegerMultisampleFetch);
+    ASSERT_FALSE(input.empty());
+
+    const Vector<ImageFetch> before = CollectImageFetches(input);
+    ASSERT_EQ(before.size(), 2u) << Disassemble(input);
+    const ImageFetch* sampleBefore = FindSampleCarryingFetch(before);
+    const ImageFetch* lodBefore = FindLodCarryingFetch(before);
+    ASSERT_NE(sampleBefore, nullptr) << Disassemble(input);
+    ASSERT_NE(lodBefore, nullptr) << Disassemble(input);
+    ASSERT_EQ(sampleBefore->maskOperandIds.size(), 1u);
+    const std::map<Uint32, Uint32> constantsBefore = CollectScalarConstants(input);
+    ASSERT_EQ(constantsBefore.count(sampleBefore->maskOperandIds.front()), 1u);
+    EXPECT_EQ(constantsBefore.at(sampleBefore->maskOperandIds.front()), 3u);
+
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::ClampMultisampleFetchesForEssl(
+        input, output, /*maxColorSamples=*/4, /*maxIntegerSamples=*/1, /*maxDepthSamples=*/4,
+        kAdvertisedMaxSamples, true));
+    ASSERT_FALSE(output.empty());
+    const String dis = Disassemble(output);
+    ASSERT_TRUE(Validates(output)) << dis;
+
+    const Vector<ImageFetch> after = CollectImageFetches(output);
+    ASSERT_EQ(after.size(), 2u) << dis;
+    const ImageFetch* sampleAfter = FindSampleCarryingFetch(after);
+    ASSERT_NE(sampleAfter, nullptr) << dis;
+    ASSERT_EQ(sampleAfter->maskOperandIds.size(), 1u) << dis;
+
+    // Sample 0 is the only one a one-sample allocation has - and it is a CONSTANT, not a computed
+    // minimum: at K == 1 there is nothing to compare against. An id that resolves in the constant
+    // table cannot also be some OpExtInst's result.
+    const std::map<Uint32, Uint32> constantsAfter = CollectScalarConstants(output);
+    ASSERT_EQ(constantsAfter.count(sampleAfter->maskOperandIds.front()), 1u) << dis;
+    EXPECT_EQ(constantsAfter.at(sampleAfter->maskOperandIds.front()), 0u) << dis;
+
+    // The float sampler2D in the same module is not multisampled, so its Lod fetch has to come
+    // through with the same image, the same mask and the same operand.
+    const ImageFetch* lodAfter = FindLodCarryingFetch(after);
+    ASSERT_NE(lodAfter, nullptr) << dis;
+    EXPECT_EQ(lodAfter->imageId, lodBefore->imageId) << dis;
+    EXPECT_EQ(lodAfter->mask, lodBefore->mask) << dis;
+    EXPECT_EQ(lodAfter->maskOperandIds, lodBefore->maskOperandIds) << dis;
+}
+
+// The same shader on a device whose integer ceiling really is what MobileGL advertises. Nothing is
+// out of range, so nothing may be rewritten - and the module must not even be re-serialised.
+TEST_F(ClampMultisampleFetchTest, LeavesTheFetchAloneWhenTheCategoryReachesTheAdvertisedMaximum) {
+    const Vector<Uint32> input = CompileFragment(kIntegerMultisampleFetch);
+    ASSERT_FALSE(input.empty());
+
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::ClampMultisampleFetchesForEssl(
+        input, output, /*maxColorSamples=*/4, /*maxIntegerSamples=*/4, /*maxDepthSamples=*/4,
+        kAdvertisedMaxSamples, true));
+    EXPECT_EQ(output, input) << Disassemble(output);
+}
+
+// A category squeezed to something above 1 cannot be answered with a constant: an index the
+// allocation does have must survive, so only the upper bound moves.
+TEST_F(ClampMultisampleFetchTest, ClampsAColorSampleWithAMinimum) {
+    const Vector<Uint32> input = CompileFragment(kColorMultisampleFetch);
+    ASSERT_FALSE(input.empty());
+
+    const Vector<ImageFetch> before = CollectImageFetches(input);
+    ASSERT_EQ(before.size(), 1u) << Disassemble(input);
+    ASSERT_EQ(before.front().maskOperandIds.size(), 1u);
+    const Uint32 originalSampleId = before.front().maskOperandIds.front();
+
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::ClampMultisampleFetchesForEssl(
+        input, output, /*maxColorSamples=*/2, /*maxIntegerSamples=*/4, /*maxDepthSamples=*/4,
+        kAdvertisedMaxSamples, true));
+    ASSERT_FALSE(output.empty());
+    const String dis = Disassemble(output);
+    ASSERT_TRUE(Validates(output)) << dis;
+
+    const Vector<ImageFetch> after = CollectImageFetches(output);
+    ASSERT_EQ(after.size(), 1u) << dis;
+    ASSERT_EQ(after.front().maskOperandIds.size(), 1u) << dis;
+    const Uint32 clampedSampleId = after.front().maskOperandIds.front();
+    EXPECT_NE(clampedSampleId, originalSampleId) << dis;
+
+    const Vector<ExtInst> extInsts = CollectExtInsts(output);
+    const ExtInst* minimum = nullptr;
+    for (const ExtInst& extInst : extInsts) {
+        if (extInst.resultId == clampedSampleId) minimum = &extInst;
+    }
+    ASSERT_NE(minimum, nullptr) << dis;
+    EXPECT_EQ(minimum->instructionNumber, kGlslStd450SMin) << dis;
+    ASSERT_EQ(minimum->operandIds.size(), 2u) << dis;
+    EXPECT_EQ(minimum->operandIds[0], originalSampleId) << dis;
+
+    // min(sample, K - 1), i.e. the last sample a two-sample allocation has.
+    const std::map<Uint32, Uint32> constants = CollectScalarConstants(output);
+    ASSERT_EQ(constants.count(minimum->operandIds[1]), 1u) << dis;
+    EXPECT_EQ(constants.at(minimum->operandIds[1]), 1u) << dis;
+}

MobileGL/MG_Test/ShaderTranspiler/DemoteFloat64Test.cpp

@@ -8,6 +8,7 @@
 
 #include <gtest/gtest.h>
 
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -484,52 +485,165 @@ TEST_F(DemoteFloat64Test, RejectsGarbageInput) {
     EXPECT_FALSE(ShaderCompiler::DemoteFloat64ToFloat32(notSpirv, output, true));
 }
 
-// EliminateFloatEqualsZeroPass turns a comparison against 0.0 into an epsilon test, a
-// workaround for drivers whose exact float compare misbehaves. Deciding WHICH constants are
-// zero used to read every float constant as though it were 32 bits wide, and on a 64-bit
-// constant that reads the LOW half of the mantissa - which is zero for 1.0lf, 2.0lf, 0.5lf and
-// every other round double a shader is likely to spell. Each of those was mistaken for 0.0, so
-// a comparison against 1.0lf became an epsilon test against ZERO, and came out true for a
-// uniform holding exactly 1.0. That is the whole of KHR-GL43.compute_shader.fp64-case2.
+// EliminateFloatEqualsZeroPass re-spells a comparison against 0.0 through GLSL.std.450 FAbs, so
+// that no float-equality instruction reaches a driver that gets one wrong. Deciding WHICH
+// constants are zero used to read every float constant as though it were 32 bits wide, and on a
+// 64-bit constant that reads the LOW half of the mantissa - which is zero for 1.0lf, 2.0lf, 0.5lf
+// and every other round double a shader is likely to spell. Each of those was mistaken for 0.0, so
+// a comparison against 1.0lf became a test against ZERO, and came out true for a uniform holding
+// exactly 1.0. That is the whole of KHR-GL43.compute_shader.fp64-case2.
+//
+// The replacement itself used to be an epsilon ball, `abs(x) < 1e-4`, which called any legitimately
+// small value zero: KHR-GL3x.buffer_objects.triangles computes a specular term of ~6e-5 at a large
+// render target and rendered black. It is exact now - `abs(x) <= 0.0` / `abs(x) > 0.0` against the
+// module's own zero constant - and the tests below pin both halves of that: only a genuine 0.0 is
+// matched, and what the compare tests against is the constant the source itself spelled.
 //
 // Asserted on the optimized module rather than through a driver, because that is where the
-// rewrite happens and its fingerprint there is unambiguous: the epsilon form introduces a
+// rewrite happens and its fingerprint there is unambiguous: the rewrite introduces a
 // GLSL.std.450 FAbs, and nothing else in these shaders would.
 namespace {
-    Bool RewritesToAnEpsilonTest(const String& source) {
+    String OptimizedDisassembly(const String& source) {
         const Vector<Uint32> input = CompileToSpirv(GL_COMPUTE_SHADER, source);
         EXPECT_FALSE(input.empty());
-        if (input.empty()) return false;
+        if (input.empty()) return {};
         Vector<Uint32> output;
         EXPECT_TRUE(ShaderCompiler::SanitizeAndOptimizeBinary(input, output, true, true));
-        return Disassemble(output).find("FAbs") != String::npos;
+        return Disassemble(output);
     }
 
-    String CompareAgainst(const String& type, const String& literal) {
+    Bool RewritesToAnAbsoluteValueTest(const String& source) {
+        return OptimizedDisassembly(source).find("FAbs") != String::npos;
+    }
+
+    String CompareAgainstUsing(const String& type, const String& op, const String& literal) {
         return "#version 430 core\n"
                "layout(local_size_x = 1) in;\n"
                "buffer Result { int g_result; };\n"
                "uniform " + type + " g_0;\n"
                "void main() {\n"
                "  g_result = 0;\n"
-               "  if (g_0 != " + literal + ") g_result = 1;\n"
+               "  if (g_0 " + op + " " + literal + ") g_result = 1;\n"
                "}\n";
     }
+
+    String CompareAgainst(const String& type, const String& literal) {
+        return CompareAgainstUsing(type, "!=", literal);
+    }
+
+    // Every instruction of a disassembly, split into whitespace-separated tokens, so an operand can
+    // be identified by position instead of by a substring another opcode might also contain -
+    // `OpFOrdLessThan` is a prefix of `OpFOrdLessThanEqual`, and those two are the whole difference
+    // between the epsilon rewrite and the exact one.
+    Vector<Vector<String>> TokenizedInstructions(const String& disassembly) {
+        Vector<Vector<String>> instructions;
+        StringStream lines(disassembly);
+        String line;
+        while (std::getline(lines, line)) {
+            Vector<String> tokens;
+            StringStream words(line);
+            String word;
+            while (words >> word) tokens.push_back(word);
+            instructions.push_back(tokens);
+        }
+        return instructions;
+    }
+
+    // The compare the rewrite leaves behind, e.g. `%22 = OpFOrdLessThanEqual %bool %21 %float_0`,
+    // or an empty vector if the module has none. These four opcodes are the only ones the pass
+    // emits and nothing else in these shaders produces one.
+    Vector<String> FindRewrittenCompare(const String& disassembly) {
+        for (const Vector<String>& tokens : TokenizedInstructions(disassembly)) {
+            if (tokens.size() < 6 || tokens[1] != "=") continue;
+            if (tokens[2] == "OpFOrdLessThanEqual" || tokens[2] == "OpFUnordLessThanEqual" ||
+                tokens[2] == "OpFOrdGreaterThan" || tokens[2] == "OpFUnordGreaterThan") {
+                return tokens;
+            }
+        }
+        return {};
+    }
+
+    // Result id of the module's 0.0 constant of the type FAbs produces - the constant the source
+    // itself spelled - found without assuming what the disassembler names it or how it prints the
+    // literal.
+    String FindZeroConstantId(const String& disassembly) {
+        const Vector<Vector<String>> instructions = TokenizedInstructions(disassembly);
+        String floatTypeId;
+        for (const Vector<String>& tokens : instructions) {
+            if (tokens.size() >= 7 && tokens[2] == "OpExtInst" && tokens[5] == "FAbs") {
+                floatTypeId = tokens[3];
+                break;
+            }
+        }
+        if (floatTypeId.empty()) return {};
+
+        for (const Vector<String>& tokens : instructions) {
+            if (tokens.size() < 5 || tokens[2] != "OpConstant" || tokens[3] != floatTypeId) continue;
+            char* end = nullptr;
+            const double value = std::strtod(tokens[4].c_str(), &end);
+            if (end != nullptr && *end == '\0' && value == 0.0) return tokens[0];
+        }
+        return {};
+    }
+
+    // The shape the pass promises: the given opcode (either NaN half of it), tested against the
+    // module's own zero constant rather than against anything this pass invented.
+    void ExpectComparedAgainstModuleZero(const String& source, const String& orderedOpcode,
+                                         const String& unorderedOpcode) {
+        const String disassembly = OptimizedDisassembly(source);
+        const Vector<String> compare = FindRewrittenCompare(disassembly);
+        ASSERT_FALSE(compare.empty()) << "no rewritten compare in the optimized module\n"
+                                      << disassembly;
+        EXPECT_TRUE(compare[2] == orderedOpcode || compare[2] == unorderedOpcode)
+            << "expected " << orderedOpcode << " (or its unordered twin), got " << compare[2] << "\n"
+            << disassembly;
+
+        const String zeroId = FindZeroConstantId(disassembly);
+        ASSERT_FALSE(zeroId.empty()) << "the module has no 0.0 constant of the abs() type\n"
+                                     << disassembly;
+        EXPECT_EQ(compare.back(), zeroId)
+            << "the rewrite compares against " << compare.back()
+            << " instead of the module's own zero; a synthesized threshold is the epsilon bug\n"
+            << disassembly;
+    }
 } // namespace
 
 TEST_F(DemoteFloat64Test, AComparisonAgainstANonZeroDoubleIsLeftAlone) {
-    EXPECT_FALSE(RewritesToAnEpsilonTest(CompareAgainst("double", "1.0LF")))
-        << "a double compared against 1.0lf was rewritten into an epsilon test against zero";
+    EXPECT_FALSE(RewritesToAnAbsoluteValueTest(CompareAgainst("double", "1.0LF")))
+        << "a double compared against 1.0lf was rewritten into a test against zero";
 }
 
 TEST_F(DemoteFloat64Test, AComparisonAgainstZeroIsStillRewritten) {
-    EXPECT_TRUE(RewritesToAnEpsilonTest(CompareAgainst("double", "0.0LF")))
+    EXPECT_TRUE(RewritesToAnAbsoluteValueTest(CompareAgainst("double", "0.0LF")))
         << "the rewrite must still fire for a genuine comparison against zero";
 }
 
 TEST_F(DemoteFloat64Test, TheThirtyTwoBitBehaviourIsUnchanged) {
-    EXPECT_FALSE(RewritesToAnEpsilonTest(CompareAgainst("float", "1.0")))
+    EXPECT_FALSE(RewritesToAnAbsoluteValueTest(CompareAgainst("float", "1.0")))
         << "a float compared against 1.0 must not be rewritten";
-    EXPECT_TRUE(RewritesToAnEpsilonTest(CompareAgainst("float", "0.0")))
+    EXPECT_TRUE(RewritesToAnAbsoluteValueTest(CompareAgainst("float", "0.0")))
         << "the 32-bit behaviour this pass shipped with must be preserved exactly";
 }
+
+// The pass matches ZERO, not "small". The old constant-is-zero test was `fabs(v) <= 1e-4`, so a
+// float compared against exactly 1e-4 was declared a comparison against zero and rewritten into
+// `abs(x) >= 1e-4` - a different question from the one the shader asked, against a constant that
+// was never zero to begin with.
+TEST_F(DemoteFloat64Test, AComparisonAgainstASmallNonZeroLiteralIsLeftAlone) {
+    EXPECT_FALSE(RewritesToAnAbsoluteValueTest(CompareAgainst("float", "0.0001")))
+        << "a float compared against 1e-4 was treated as a comparison against zero";
+    EXPECT_FALSE(RewritesToAnAbsoluteValueTest(CompareAgainst("double", "0.0001LF")))
+        << "the 64-bit accessor must judge the constant just as exactly as the 32-bit one";
+}
+
+// What replaces the compare, not just that something did. Both properties here are what makes the
+// rewrite exact rather than a tolerance, and neither is visible in the FAbs fingerprint above.
+TEST_F(DemoteFloat64Test, TheRewriteComparesAbsAgainstTheModulesOwnZero) {
+    // `x == 0.0` -> `abs(x) <= 0.0`. The equality has to be INSIDE the replacement: with a strict
+    // `<` and no epsilon left to hide behind, +/-0 would stop comparing equal to zero.
+    ExpectComparedAgainstModuleZero(CompareAgainstUsing("float", "==", "0.0"),
+                                    "OpFOrdLessThanEqual", "OpFUnordLessThanEqual");
+    // `x != 0.0` -> `abs(x) > 0.0`, the strict complement of the above.
+    ExpectComparedAgainstModuleZero(CompareAgainstUsing("float", "!=", "0.0"), "OpFOrdGreaterThan",
+                                    "OpFUnordGreaterThan");
+}

MobileGL/MG_Test/ShaderTranspiler/LowerViewportIndexTest.cpp

@@ -0,0 +1,237 @@
+// MobileGL - MobileGL/MG_Test/ShaderTranspiler/LowerViewportIndexTest.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+//
+// LowerViewportIndexPass is the DirectGLES fallback for a driver with no GL_OES_viewport_array.
+// The thing it prevents is not a wrong pixel but a missing program: ESSL has no core
+// gl_ViewportIndex at any version, SPIRV-Cross prints the identifier bare, and the driver rejects
+// the stage - after which DirectGLES binds program 0 and every draw renders nothing while
+// GL_LINK_STATUS still answers TRUE. So what has to hold is textual and structural at once: the
+// emitted ESSL must stop naming the builtin, the module must stay valid, and gl_Layer - which IS
+// core in ESSL 3.20 geometry shaders - must come through untouched.
+//
+// Real GLSL through the same glslang path the backends use, rather than hand-assembled words, for
+// the same reason MG_Test/Pipeline/ViewportIndexReflectionTest.cpp does it: what matters is what
+// glslang actually emits for these shaders.
+
+#include <gtest/gtest.h>
+
+#include <string>
+#include <vector>
+
+#include "Includes.h"
+#include "Init.h"
+#include <MG_Util/ShaderTranspiler/ShaderCompiler.h>
+#include <MG_Util/ShaderTranspiler/SpvcSession.h>
+#include <MG_Util/ShaderTranspiler/Types.h>
+
+#include <spirv-tools/libspirv.hpp>
+
+using namespace MobileGL;
+using MobileGL::MG_Util::ShaderTranspiler::SessionUsageBit;
+using MobileGL::MG_Util::ShaderTranspiler::ShaderCompiler;
+using MobileGL::MG_Util::ShaderTranspiler::SpvcSession;
+
+namespace {
+    Vector<Uint32> CompileToSpirv(GLenum stage, const String& source) {
+        using namespace MG_Util::ShaderTranspiler;
+        ShaderAttrib shaderAttrib{.shaderType = stage, .sourceStr = source};
+        auto shaderResult = ShaderCompiler::CompileShader(shaderAttrib);
+        EXPECT_TRUE(shaderResult) << (shaderResult ? String{} : shaderResult.error().log);
+        if (!shaderResult) return {};
+
+        ProgramAttrib programAttrib{.shaders = {shaderResult.value()}};
+        auto programResult = ShaderCompiler::LinkProgram(programAttrib);
+        EXPECT_TRUE(programResult) << (programResult ? String{} : programResult.error().log);
+        if (!programResult) return {};
+
+        ProgramBinaryAttrib binaryAttrib{.shaderTypes = {stage}, .program = *programResult.value()};
+        auto binaryResult = ShaderCompiler::GetSpirvBinaryFromProgram(binaryAttrib);
+        EXPECT_TRUE(binaryResult) << (binaryResult ? String{} : binaryResult.error().log);
+        if (!binaryResult || binaryResult->empty()) return {};
+        return binaryResult->front();
+    }
+
+    String Disassemble(const Vector<Uint32>& spirv) {
+        spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+        String text;
+        tools.Disassemble(spirv, &text);
+        return text;
+    }
+
+    // ESSL 320, i.e. exactly what the DirectGLES transpile asks SPIRV-Cross for.
+    String Transpile(const Vector<Uint32>& spirv) {
+        SpvcSession session(spirv, SessionUsageBit::Transpile);
+        auto essl = ShaderCompiler::DecompileShader(session);
+        EXPECT_TRUE(essl) << (essl ? String{} : essl.error().log);
+        return essl ? essl.value() : String{};
+    }
+
+    Bool Contains(const String& haystack, const String& needle) {
+        return haystack.find(needle) != String::npos;
+    }
+
+    // KHR-GL4x.viewport_array.draw_to_single_layer_with_multiple_viewports' geometry stage in
+    // miniature: sixteen invocations, each routing its primitive to its own viewport. This is the
+    // shape that today loses the whole program on a driver without GL_OES_viewport_array.
+    const char* const kGeometryWritesViewportIndex = R"(#version 410 core
+layout(points, invocations = 16) in;
+layout(triangle_strip, max_vertices = 4) out;
+void main() {
+    gl_ViewportIndex = gl_InvocationID;
+    gl_Position = vec4(-1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4(-1.0,  1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0,  1.0, 0.0, 1.0); EmitVertex();
+    EndPrimitive();
+}
+)";
+
+    // Layered rendering, not viewport routing. gl_Layer IS core in ESSL 3.20 geometry shaders, so
+    // demoting it would break a Minecraft-style cubemap pass that works today.
+    const char* const kGeometryWritesLayerOnly = R"(#version 410 core
+layout(points, invocations = 6) in;
+layout(triangle_strip, max_vertices = 4) out;
+void main() {
+    gl_Layer = gl_InvocationID;
+    gl_Position = vec4(-1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4(-1.0,  1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0,  1.0, 0.0, 1.0); EmitVertex();
+    EndPrimitive();
+}
+)";
+
+    // Both at once, which is the case that separates "lowers the right builtin" from "lowers every
+    // builtin it can reach": KHR-GL4x.viewport_array.draw_multiple_layers writes both.
+    const char* const kGeometryWritesBoth = R"(#version 410 core
+layout(points, invocations = 16) in;
+layout(triangle_strip, max_vertices = 4) out;
+void main() {
+    gl_ViewportIndex = gl_InvocationID;
+    gl_Layer = gl_InvocationID;
+    gl_Position = vec4(-1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4(-1.0,  1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0,  1.0, 0.0, 1.0); EmitVertex();
+    EndPrimitive();
+}
+)";
+
+    const char* const kPlainGeometry = R"(#version 410 core
+layout(points, invocations = 1) in;
+layout(triangle_strip, max_vertices = 4) out;
+void main() {
+    gl_Position = vec4(-1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0, -1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4(-1.0,  1.0, 0.0, 1.0); EmitVertex();
+    gl_Position = vec4( 1.0,  1.0, 0.0, 1.0); EmitVertex();
+    EndPrimitive();
+}
+)";
+} // namespace
+
+class LowerViewportIndexTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        MobileGL::Initialize();
+        m_validationFailuresAtStart = ShaderCompiler::SpirvValidationFailureCount();
+    }
+
+    void TearDown() override {
+        EXPECT_EQ(ShaderCompiler::SpirvValidationFailureCount(), m_validationFailuresAtStart)
+            << "the lowered module did not survive spirv-val";
+    }
+
+    Uint64 m_validationFailuresAtStart = 0;
+};
+
+// The probe is the gate that keeps every ordinary stage off an optimizer round trip, so it has to
+// answer no for a shader that never routes a viewport - and yes for the one that does.
+TEST_F(LowerViewportIndexTest, TheProbeAnswersOnlyForAViewportIndexWriter) {
+    const Vector<Uint32> plain = CompileToSpirv(GL_GEOMETRY_SHADER, kPlainGeometry);
+    ASSERT_FALSE(plain.empty());
+    EXPECT_FALSE(ShaderCompiler::DeclaresViewportIndexBuiltin(plain));
+
+    const Vector<Uint32> layerOnly = CompileToSpirv(GL_GEOMETRY_SHADER, kGeometryWritesLayerOnly);
+    ASSERT_FALSE(layerOnly.empty());
+    EXPECT_FALSE(ShaderCompiler::DeclaresViewportIndexBuiltin(layerOnly));
+
+    const Vector<Uint32> writer = CompileToSpirv(GL_GEOMETRY_SHADER, kGeometryWritesViewportIndex);
+    ASSERT_FALSE(writer.empty());
+    EXPECT_TRUE(ShaderCompiler::DeclaresViewportIndexBuiltin(writer));
+
+    // Runs on every stage of every program on a driver without the extension, so it must survive a
+    // stage that produced no SPIR-V rather than pushing a parse diagnostic for it.
+    EXPECT_FALSE(ShaderCompiler::DeclaresViewportIndexBuiltin({}));
+}
+
+// The whole point: the emitted ESSL must stop naming a builtin the language does not have.
+TEST_F(LowerViewportIndexTest, DemotesTheBuiltinToAnOrdinaryGlobal) {
+    const Vector<Uint32> input = CompileToSpirv(GL_GEOMETRY_SHADER, kGeometryWritesViewportIndex);
+    ASSERT_FALSE(input.empty());
+
+    // Negative control, and the bug itself: untouched, SPIRV-Cross prints gl_ViewportIndex into
+    // ESSL 320 and asks for no extension to go with it.
+    const String before = Transpile(input);
+    EXPECT_TRUE(Contains(before, "gl_ViewportIndex")) << before;
+
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::LowerViewportIndexForEssl(input, output, true));
+    ASSERT_FALSE(output.empty());
+
+    const String dis = Disassemble(output);
+    spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+    ASSERT_TRUE(tools.Validate(output)) << dis;
+    EXPECT_FALSE(Contains(dis, "BuiltIn ViewportIndex")) << dis;
+    EXPECT_TRUE(Contains(dis, "mg_ViewportIndex")) << dis;
+    EXPECT_TRUE(Contains(dis, "Private")) << dis;
+
+    const String after = Transpile(output);
+    EXPECT_TRUE(Contains(after, "mg_ViewportIndex")) << after;
+    EXPECT_FALSE(Contains(after, "gl_ViewportIndex")) << after;
+}
+
+// gl_Layer is core in ESSL 3.20 geometry shaders and layered rendering works on this backend
+// today. Lowering it too would trade one silent failure for another.
+TEST_F(LowerViewportIndexTest, LeavesGlLayerAlone) {
+    const Vector<Uint32> input = CompileToSpirv(GL_GEOMETRY_SHADER, kGeometryWritesBoth);
+    ASSERT_FALSE(input.empty());
+
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::LowerViewportIndexForEssl(input, output, true));
+    ASSERT_FALSE(output.empty());
+
+    const String dis = Disassemble(output);
+    spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+    ASSERT_TRUE(tools.Validate(output)) << dis;
+    EXPECT_FALSE(Contains(dis, "BuiltIn ViewportIndex")) << dis;
+    EXPECT_TRUE(Contains(dis, "BuiltIn Layer")) << dis;
+
+    const String after = Transpile(output);
+    EXPECT_TRUE(Contains(after, "gl_Layer")) << after;
+    EXPECT_FALSE(Contains(after, "gl_ViewportIndex")) << after;
+}
+
+// Every other stage on a driver without the extension goes through this pass too (behind the
+// probe), so a module it has nothing to do with must come out saying exactly what it said.
+TEST_F(LowerViewportIndexTest, LeavesAModuleWithoutTheBuiltinUntouched) {
+    const Vector<Uint32> input = CompileToSpirv(GL_GEOMETRY_SHADER, kPlainGeometry);
+    ASSERT_FALSE(input.empty());
+
+    const String before = Transpile(input);
+
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::LowerViewportIndexForEssl(input, output, true));
+    ASSERT_FALSE(output.empty());
+
+    const String dis = Disassemble(output);
+    spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+    ASSERT_TRUE(tools.Validate(output)) << dis;
+    EXPECT_FALSE(Contains(dis, "mg_ViewportIndex")) << dis;
+    EXPECT_EQ(Transpile(output), before);
+}

MobileGL/MG_Test/ShaderTranspiler/UniquifyIoBlockNamesTest.cpp

@@ -0,0 +1,262 @@
+// MobileGL - MobileGL/MG_Test/ShaderTranspiler/UniquifyIoBlockNamesTest.cpp
+// Copyright (c) 2025-2026 MobileGL-Dev
+// Licensed under the GNU Lesser General Public License v3.0:
+//   https://www.gnu.org/licenses/gpl-3.0.txt
+//   https://www.gnu.org/licenses/lgpl-3.0.txt
+// SPDX-License-Identifier: LGPL-3.0-only
+// End of Source File Header
+
+#include <gtest/gtest.h>
+
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "Includes.h"
+#include "Init.h"
+#include <MG_Util/ShaderTranspiler/ShaderCompiler.h>
+#include <MG_Util/ShaderTranspiler/SpvcSession.h>
+#include <MG_Util/ShaderTranspiler/Types.h>
+
+#include <spirv-tools/libspirv.hpp>
+
+using namespace MobileGL;
+using MobileGL::MG_Util::ShaderTranspiler::SessionUsageBit;
+using MobileGL::MG_Util::ShaderTranspiler::ShaderCompiler;
+using MobileGL::MG_Util::ShaderTranspiler::SpvcSession;
+
+namespace {
+    Vector<Uint32> CompileToSpirv(GLenum stage, const String& source) {
+        using namespace MG_Util::ShaderTranspiler;
+        ShaderAttrib shaderAttrib{.shaderType = stage, .sourceStr = source};
+        auto shaderResult = ShaderCompiler::CompileShader(shaderAttrib);
+        EXPECT_TRUE(shaderResult) << (shaderResult ? String{} : shaderResult.error().log);
+        if (!shaderResult) return {};
+
+        ProgramAttrib programAttrib{.shaders = {shaderResult.value()}};
+        auto programResult = ShaderCompiler::LinkProgram(programAttrib);
+        EXPECT_TRUE(programResult) << (programResult ? String{} : programResult.error().log);
+        if (!programResult) return {};
+
+        ProgramBinaryAttrib binaryAttrib{.shaderTypes = {stage}, .program = *programResult.value()};
+        auto binaryResult = ShaderCompiler::GetSpirvBinaryFromProgram(binaryAttrib);
+        EXPECT_TRUE(binaryResult) << (binaryResult ? String{} : binaryResult.error().log);
+        if (!binaryResult || binaryResult->empty()) return {};
+        return binaryResult->front();
+    }
+
+    String Disassemble(const Vector<Uint32>& spirv) {
+        spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+        String text;
+        tools.Disassemble(spirv, &text);
+        return text;
+    }
+
+    String Transpile(const Vector<Uint32>& spirv) {
+        SpvcSession session(spirv, SessionUsageBit::Transpile);
+        auto essl = ShaderCompiler::DecompileShader(session);
+        EXPECT_TRUE(essl) << (essl ? String{} : essl.error().log);
+        return essl ? essl.value() : String{};
+    }
+
+    // The tessellation evaluation stage of
+    // KHR-GL42/43.shading_language_420pack.length_of_vector_and_matrix_* and
+    // .qualifier_order_block_*, reduced to the shape that matters: ONE block name used for
+    // both the block this stage consumes and the block it produces. Legal desktop GLSL - the
+    // input and output block namespaces are separate - and something SPIRV-Cross re-emits
+    // verbatim, so the ESSL it produces declares two different blocks called TCSOutputBlock.
+    const char* kCollidingTessEvalSource = R"(#version 420 core
+layout(isolines, point_mode) in;
+
+in  vec4 tcs_tes_result[];
+out vec4 tes_gs_result;
+
+in TCSOutputBlock {
+    vec4 tcs_tes_variable;
+} input_block[];
+out TCSOutputBlock {
+    vec4 tes_gs_variable;
+} output_block;
+
+void main()
+{
+    tes_gs_result = tcs_tes_result[0];
+    output_block.tes_gs_variable = input_block[0].tcs_tes_variable;
+}
+)";
+
+    // The same stage with the two blocks already named apart, which is the overwhelmingly
+    // common shape and the one that must go through untouched.
+    const char* kDistinctTessEvalSource = R"(#version 420 core
+layout(isolines, point_mode) in;
+
+in  vec4 tcs_tes_result[];
+out vec4 tes_gs_result;
+
+in TCSOutputBlock {
+    vec4 tcs_tes_variable;
+} input_block[];
+out TESOutputBlock {
+    vec4 tes_gs_variable;
+} output_block;
+
+void main()
+{
+    tes_gs_result = tcs_tes_result[0];
+    output_block.tes_gs_variable = input_block[0].tcs_tes_variable;
+}
+)";
+
+    // gl_PerVertex is an Input block AND an Output block of one name in every tessellation
+    // and geometry stage. It is the language's block, not the shader's, so it must never be
+    // reported and never be renamed.
+    const char* kBuiltinBlockOnlyTessEvalSource = R"(#version 420 core
+layout(isolines, point_mode) in;
+
+void main()
+{
+    gl_Position = gl_in[0].gl_Position;
+}
+)";
+} // namespace
+
+class UniquifyIoBlockNamesTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        MobileGL::Initialize();
+        m_validationFailuresAtStart = ShaderCompiler::SpirvValidationFailureCount();
+    }
+
+    void TearDown() override {
+        EXPECT_EQ(ShaderCompiler::SpirvValidationFailureCount(), m_validationFailuresAtStart)
+            << "the renamed module did not survive spirv-val";
+    }
+
+    Uint64 m_validationFailuresAtStart = 0;
+};
+
+TEST_F(UniquifyIoBlockNamesTest, ProbeReportsABlockNameUsedInBothDirections) {
+    const Vector<Uint32> input = CompileToSpirv(GL_TESS_EVALUATION_SHADER, kCollidingTessEvalSource);
+    ASSERT_FALSE(input.empty());
+
+    std::set<String> colliding;
+    std::set<String> declared;
+    ShaderCompiler::ProbeIoBlockNamesForEssl(input, colliding, declared);
+
+    EXPECT_EQ(colliding, (std::set<String>{"TCSOutputBlock"}));
+    // The name set the caller picks a replacement out of has to contain what the module
+    // already spells, or the replacement could land on top of an existing declaration.
+    EXPECT_NE(declared.find("TCSOutputBlock"), declared.end());
+    EXPECT_NE(declared.find("input_block"), declared.end());
+    EXPECT_NE(declared.find("output_block"), declared.end());
+}
+
+TEST_F(UniquifyIoBlockNamesTest, ProbeIgnoresAStageWhoseBlocksAlreadyHaveDistinctNames) {
+    const Vector<Uint32> input = CompileToSpirv(GL_TESS_EVALUATION_SHADER, kDistinctTessEvalSource);
+    ASSERT_FALSE(input.empty());
+
+    std::set<String> colliding;
+    std::set<String> declared;
+    ShaderCompiler::ProbeIoBlockNamesForEssl(input, colliding, declared);
+
+    EXPECT_TRUE(colliding.empty());
+    EXPECT_NE(declared.find("TCSOutputBlock"), declared.end());
+}
+
+TEST_F(UniquifyIoBlockNamesTest, ProbeNeverReportsTheBuiltinBlock) {
+    const Vector<Uint32> input =
+        CompileToSpirv(GL_TESS_EVALUATION_SHADER, kBuiltinBlockOnlyTessEvalSource);
+    ASSERT_FALSE(input.empty());
+
+    std::set<String> colliding;
+    std::set<String> declared;
+    ShaderCompiler::ProbeIoBlockNamesForEssl(input, colliding, declared);
+
+    // gl_PerVertex is read through gl_in and written through gl_Position, i.e. it is exactly
+    // the in-and-out-under-one-name shape - and renaming it would invent a block no driver
+    // knows.
+    EXPECT_TRUE(colliding.empty()) << "gl_PerVertex must never enter the rename plan";
+}
+
+TEST_F(UniquifyIoBlockNamesTest, RenamesTheTwoBlocksApartInTheEmittedEssl) {
+    const Vector<Uint32> input = CompileToSpirv(GL_TESS_EVALUATION_SHADER, kCollidingTessEvalSource);
+    ASSERT_FALSE(input.empty());
+    // The generated ESSL really does declare the block twice under one name before the fix -
+    // pinning the defect, not just the repair.
+    const String before = Transpile(input);
+    EXPECT_NE(before.find("in TCSOutputBlock"), String::npos) << before;
+    EXPECT_NE(before.find("out TCSOutputBlock"), String::npos) << before;
+
+    // The plan the DirectGLES program build makes for a five-stage program: what this stage
+    // consumes is spelled after the tessellation control stage (pipeline index 1) and what it
+    // produces after itself (pipeline index 2).
+    const std::map<String, String> inputRenames{{"TCSOutputBlock", "TCSOutputBlock_mgio1"}};
+    const std::map<String, String> outputRenames{{"TCSOutputBlock", "TCSOutputBlock_mgio2"}};
+
+    std::set<String> renamed;
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::UniquifyIoBlockNamesForEssl(input, inputRenames, outputRenames, renamed,
+                                                            output, true));
+    ASSERT_FALSE(output.empty());
+    EXPECT_EQ(renamed, (std::set<String>{"TCSOutputBlock"}));
+
+    const String dis = Disassemble(output);
+    spvtools::SpirvTools tools(SPV_ENV_VULKAN_1_1);
+    ASSERT_TRUE(tools.Validate(output)) << dis;
+    EXPECT_EQ(dis.find("\"TCSOutputBlock\""), String::npos)
+        << "the colliding name is still on a block struct:\n"
+        << dis;
+    EXPECT_NE(dis.find("\"TCSOutputBlock_mgio1\""), String::npos) << dis;
+    EXPECT_NE(dis.find("\"TCSOutputBlock_mgio2\""), String::npos) << dis;
+
+    const String after = Transpile(output);
+    EXPECT_NE(after.find("TCSOutputBlock_mgio1"), String::npos) << after;
+    EXPECT_NE(after.find("TCSOutputBlock_mgio2"), String::npos) << after;
+    // Only the block TYPE name moves: the instance names are what the body reads and writes
+    // through, and the member names are half of what ES matches the interface by.
+    EXPECT_NE(after.find("input_block"), String::npos) << after;
+    EXPECT_NE(after.find("output_block"), String::npos) << after;
+    EXPECT_NE(after.find("tcs_tes_variable"), String::npos) << after;
+    EXPECT_NE(after.find("tes_gs_variable"), String::npos) << after;
+}
+
+TEST_F(UniquifyIoBlockNamesTest, RenamesOnlyTheDirectionTheCallerPlanned) {
+    const Vector<Uint32> input = CompileToSpirv(GL_TESS_EVALUATION_SHADER, kCollidingTessEvalSource);
+    ASSERT_FALSE(input.empty());
+
+    // A separate-shader-objects program that ends at this stage plans no output rename,
+    // because the block's consumer lives in another program that never saw the plan.
+    const std::map<String, String> inputRenames{{"TCSOutputBlock", "TCSOutputBlock_mgio1"}};
+
+    std::set<String> renamed;
+    Vector<Uint32> output;
+    ASSERT_TRUE(
+        ShaderCompiler::UniquifyIoBlockNamesForEssl(input, inputRenames, {}, renamed, output, true));
+    ASSERT_FALSE(output.empty());
+    EXPECT_EQ(renamed, (std::set<String>{"TCSOutputBlock"}));
+
+    const String dis = Disassemble(output);
+    EXPECT_NE(dis.find("\"TCSOutputBlock_mgio1\""), String::npos) << dis;
+    // The output block keeps the name the other program still spells.
+    EXPECT_NE(dis.find("\"TCSOutputBlock\""), String::npos) << dis;
+    EXPECT_EQ(dis.find("\"TCSOutputBlock_mgio2\""), String::npos) << dis;
+}
+
+TEST_F(UniquifyIoBlockNamesTest, ReportsNothingWhenThePlanNamesNoBlockThisStageDeclares) {
+    const Vector<Uint32> input = CompileToSpirv(GL_TESS_EVALUATION_SHADER, kDistinctTessEvalSource);
+    ASSERT_FALSE(input.empty());
+
+    const std::map<String, String> renames{{"SomeOtherBlock", "SomeOtherBlock_mgio2"}};
+
+    std::set<String> renamed;
+    Vector<Uint32> output;
+    ASSERT_TRUE(ShaderCompiler::UniquifyIoBlockNamesForEssl(input, renames, renames, renamed, output, true));
+    // Empty is what tells the DirectGLES program build to keep the module it already had
+    // instead of adopting the optimizer's re-serialised copy.
+    EXPECT_TRUE(renamed.empty());
+
+    const String dis = Disassemble(output);
+    EXPECT_NE(dis.find("\"TCSOutputBlock\""), String::npos) << dis;
+    EXPECT_NE(dis.find("\"TESOutputBlock\""), String::npos) << dis;
+}

MobileGL/MG_Test/State/NegativeApiErrorsTest.cpp

@@ -18,6 +18,11 @@
 //     errors that guard a parameter-buffer draw.
 //   * KHR-GL43.compute_shader.api-indirect / .api-program.
 //   * KHR-GLxx.texture_storage.compressed_data - compressed formats on TEXTURE_3D.
+//   * KHR-GL32.api.coverage - glFenceSync's condition/flags and glWaitSync's flags/timeout.
+//   * KHR-GL31.api.coverage - a draw's mode INVALID_ENUM has to outrank MobileGL's own
+//     no-current-program guard.
+//   * KHR-GL30.api.coverage - glBlitFramebuffer's mask bits, filter enum and the LINEAR-with-
+//     depth/stencil rule.
 // Plus the indexed-getter parity RC-7b is about: glGetBooleani_v / glGetInteger64i_v /
 // glGetFloati_v / glGetDoublei_v must answer every pname glGetIntegeri_v answers.
 //
@@ -33,10 +38,12 @@
 #include "Init.h"
 #include <MG_Impl/GLImpl/Buffer/GL_Buffer.h>
 #include <MG_Impl/GLImpl/Drawing/GL_Drawing.h>
+#include <MG_Impl/GLImpl/Framebuffer/GL_Framebuffer.h>
 #include <MG_Impl/GLImpl/Getter/GL_Getter.h>
 #include <MG_Impl/GLImpl/Program/GL_Program.h>
 #include <MG_Impl/GLImpl/RenderState/GL_RenderState.h>
 #include <MG_Impl/GLImpl/Sampler/GL_Sampler.h>
+#include <MG_Impl/GLImpl/Sync/GL_Sync.h>
 #include <MG_Impl/GLImpl/Texture/GL_Texture.h>
 #include <MG_Impl/GLImpl/VertexArray/GL_VertexArray.h>
 #include <MG_State/GLState/Core.h>
@@ -470,4 +477,114 @@ void main() { g_color = vec4(1); }
         EXPECT_EQ(offset, 2048);
         EXPECT_EQ(GetError(), GL_NO_ERROR);
     }
+
+    // KHR-GL32.api.coverage: glFenceSync and glWaitSync took every argument they were handed and
+    // reported GL_NO_ERROR for the two calls GL 4.6 core 4.1.2 requires to fail. A rejected
+    // glFenceSync must also hand back 0 rather than a live handle.
+    TEST_F(NegativeApiErrorsTest, SyncEntryPointsRejectTheirIllegalArguments) {
+        DrainErrors();
+
+        RunRows({
+            {"glFenceSync with a condition other than GL_SYNC_GPU_COMMANDS_COMPLETE",
+             [] { EXPECT_EQ(FenceSync(GL_SYNC_FENCE, 0), nullptr); }, GL_INVALID_ENUM},
+            {"glFenceSync with nonzero flags", [] { EXPECT_EQ(FenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 1), nullptr); },
+             GL_INVALID_VALUE},
+        });
+
+        // The legal fence still works, and with no backend function table it is the always-signaled
+        // fallback - which is all this GPU-free suite needs to reach glWaitSync's own checks.
+        const GLsync sync = FenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
+        ASSERT_NE(sync, nullptr);
+        EXPECT_EQ(GetError(), GL_NO_ERROR);
+        EXPECT_EQ(IsSync(sync), GL_TRUE);
+
+        RunRows({
+            {"glWaitSync with nonzero flags", [&] { WaitSync(sync, GL_SYNC_FLUSH_COMMANDS_BIT, GL_TIMEOUT_IGNORED); },
+             GL_INVALID_VALUE},
+            {"glWaitSync with a finite timeout", [&] { WaitSync(sync, 0, 1000000000ull); }, GL_INVALID_VALUE},
+            {"glWaitSync with the only legal argument pair", [&] { WaitSync(sync, 0, GL_TIMEOUT_IGNORED); },
+             GL_NO_ERROR},
+        });
+
+        DeleteSync(sync);
+        EXPECT_EQ(GetError(), GL_NO_ERROR);
+    }
+
+    // KHR-GL31.api.coverage's first two calls are glDrawArraysInstanced / glDrawElementsInstanced
+    // with mode GL_POINTS-1 against a context that has no program and no VAO bound, and they must
+    // answer GL_INVALID_ENUM. MobileGL's own "there is no current program" guard - which the spec
+    // does not list as a draw error at all - used to run first and shadowed the enum check with
+    // GL_INVALID_OPERATION. Nothing here reaches a backend: the mode is rejected before the guard.
+    TEST_F(NegativeApiErrorsTest, BadPrimitiveModeOutranksTheNoProgramGuard) {
+        DrainErrors();
+        // Exactly what the coverage test passes: GL_POINTS is 0, so this is 0xFFFFFFFF.
+        constexpr GLenum kBadMode = static_cast<GLenum>(GL_POINTS - 1);
+
+        RunRows({
+            {"glDrawArraysInstanced with an unaccepted mode", [] { DrawArraysInstanced(kBadMode, 0, 3, 4); },
+             GL_INVALID_ENUM},
+            {"glDrawElementsInstanced with an unaccepted mode",
+             [] { DrawElementsInstanced(kBadMode, 3, GL_UNSIGNED_INT, nullptr, 4); }, GL_INVALID_ENUM},
+            {"glDrawArrays with an unaccepted mode", [] { DrawArrays(kBadMode, 0, 3); }, GL_INVALID_ENUM},
+            {"glDrawElements with an unaccepted mode",
+             [] { DrawElements(kBadMode, 3, GL_UNSIGNED_INT, nullptr); }, GL_INVALID_ENUM},
+            {"glMultiDrawArrays with an unaccepted mode",
+             [] { MultiDrawArrays(kBadMode, nullptr, nullptr, 0); }, GL_INVALID_ENUM},
+            {"glDrawRangeElements with an unaccepted mode",
+             [] { DrawRangeElements(kBadMode, 0, 2, 3, GL_UNSIGNED_INT, nullptr); }, GL_INVALID_ENUM},
+            {"glDrawElementsIndirect with an unaccepted mode",
+             [] { DrawElementsIndirect(kBadMode, GL_UNSIGNED_INT, nullptr); }, GL_INVALID_ENUM},
+            {"glDrawArraysIndirect with an unaccepted mode", [] { DrawArraysIndirect(kBadMode, nullptr); },
+             GL_INVALID_ENUM},
+            // A mode the enum check accepts falls through to the guard, so the INVALID_OPERATION
+            // that used to win is still raised for the calls it is actually about.
+            {"glDrawArrays with a legal mode and no program bound", [] { DrawArrays(GL_TRIANGLES, 0, 3); },
+             GL_INVALID_OPERATION},
+        });
+    }
+
+    // KHR-GL30.api.coverage's glBlitFramebuffer sub-check. The frontend passed mask and filter
+    // straight through, and DirectGLES drains the driver's error queue around the blit so the ES
+    // rejection never surfaced either - both illegal calls reported GL_NO_ERROR. Every row here
+    // is rejected before the backend function pointer is reached, which is what lets this
+    // GPU-free suite run them at all.
+    TEST_F(NegativeApiErrorsTest, BlitFramebufferRejectsBadMasksAndFilters) {
+        DrainErrors();
+        // The bit the coverage test smuggles in: a legal glMapBufferRange flag, not a blit one.
+        constexpr GLbitfield kForeignBit = GL_MAP_INVALIDATE_BUFFER_BIT;
+
+        RunRows({
+            {"glBlitFramebuffer with a mask bit outside COLOR|DEPTH|STENCIL",
+             [] {
+                 BlitFramebuffer(0, 0, 16, 16, 0, 0, 16, 16, GL_COLOR_BUFFER_BIT | kForeignBit, GL_NEAREST);
+             },
+             GL_INVALID_VALUE},
+            {"glBlitFramebuffer with a filter that is neither GL_NEAREST nor GL_LINEAR",
+             [] { BlitFramebuffer(0, 0, 16, 16, 0, 0, 16, 16, GL_COLOR_BUFFER_BIT, GL_NONE); }, GL_INVALID_ENUM},
+            {"glBlitFramebuffer of colour+stencil with GL_LINEAR",
+             [] {
+                 BlitFramebuffer(0, 0, 16, 16, 0, 0, 16, 16, GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT, GL_LINEAR);
+             },
+             GL_INVALID_OPERATION},
+            {"glBlitFramebuffer of depth with GL_LINEAR",
+             [] { BlitFramebuffer(0, 0, 16, 16, 0, 0, 16, 16, GL_DEPTH_BUFFER_BIT, GL_LINEAR); },
+             GL_INVALID_OPERATION},
+            // The DSA form has to answer identically.
+            {"glBlitNamedFramebuffer with a mask bit outside COLOR|DEPTH|STENCIL",
+             [] {
+                 BlitNamedFramebuffer(0, 0, 0, 0, 16, 16, 0, 0, 16, 16, GL_COLOR_BUFFER_BIT | kForeignBit,
+                                      GL_NEAREST);
+             },
+             GL_INVALID_VALUE},
+            {"glBlitNamedFramebuffer with a bad filter",
+             [] { BlitNamedFramebuffer(0, 0, 0, 0, 16, 16, 0, 0, 16, 16, GL_COLOR_BUFFER_BIT, GL_NONE); },
+             GL_INVALID_ENUM},
+            {"glBlitNamedFramebuffer of depth+stencil with GL_LINEAR",
+             [] {
+                 BlitNamedFramebuffer(0, 0, 0, 0, 16, 16, 0, 0, 16, 16,
+                                      GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT, GL_LINEAR);
+             },
+             GL_INVALID_OPERATION},
+        });
+    }
 } // namespace

MobileGL/MG_Test/Texture/TextureTest.cpp

@@ -377,6 +377,40 @@ TEST_F(TextureTest, ClearTexImageErrorContracts) {
     EXPECT_EQ(MG_Impl::GLImpl::GetError(), static_cast<GLenum>(GL_INVALID_ENUM));
 }
 
+// GL 4.6 core 8.19: a compressed internal format is INVALID_OPERATION for both clear entry points.
+// The generic GL_COMPRESSED_* enums are the half that needs its own tag - MobileGL answers them
+// with uncompressed storage on purpose, so by the time the clear runs the level looks like any
+// other RGBA8 image unless the REQUEST was recorded alongside it.
+TEST_F(TextureTest, ClearTexImageRejectsCompressedTextures) {
+    GLuint genericTexture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &genericTexture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, genericTexture);
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGBA, 4, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::ClearTexImage(genericTexture, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+    MG_Impl::GLImpl::ClearTexSubImage(genericTexture, 0, 0, 0, 0, 4, 4, 1, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+
+    // A specific compressed internalformat is refused through the tag the level already carried...
+    GLuint specificTexture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &specificTexture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, specificTexture);
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RED_RGTC1, 8, 8, 0, GL_RED, GL_UNSIGNED_BYTE,
+                                nullptr);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::ClearTexImage(specificTexture, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+
+    // ...and respecifying the level with an uncompressed format makes it clearable again, because
+    // AllocateStorage clears both tags.
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_R8, 8, 8, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::ClearTexImage(specificTexture, 0, GL_RED, GL_UNSIGNED_BYTE, nullptr);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
 // GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT is float state that must answer every numeric query: GetFloatv
 // is authoritative and GetIntegerv would otherwise fall through to its INVALID_ENUM default.
 TEST_F(TextureTest, MaxTextureMaxAnisotropyIsAnsweredFromTheBackendLimit) {
@@ -1023,6 +1057,32 @@ TEST_F(TextureTest, TexImage2DAcceptsSpecCompliantFormatCombinations) {
     EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
 }
 
+// GL_STENCIL_INDEX is the unsized base format for stencil-only storage, and refusing it as an
+// internal format killed the ARB_clear_texture stencil case in its own setup - before it could
+// reach the calls it actually tests. The stencil-only transfer format stays paired with
+// stencil-only storage in both directions, which is what keeps those clears erroring.
+TEST_F(TextureTest, StencilIndexIsATextureInternalFormatPairedOnlyWithStencilStorage) {
+    GLuint texture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &texture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, texture);
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_STENCIL_INDEX, 4, 4, 0, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE,
+                                nullptr);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    const auto textureObject = MG_State::pGLContext->GetTextureObject(texture);
+    ASSERT_NE(textureObject, nullptr);
+    EXPECT_EQ(textureObject->GetFormat(), TextureInternalFormat::StencilIndex8);
+
+    // A colour transfer format against stencil storage is still INVALID_OPERATION, so the clear
+    // the conformance case makes next fails the way it is supposed to.
+    MG_Impl::GLImpl::ClearTexImage(texture, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+
+    // ...and the other direction: GL_STENCIL_INDEX against colour storage stays illegal.
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 4, 4, 0, GL_STENCIL_INDEX, GL_UNSIGNED_BYTE, nullptr);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+}
+
 // Desktop GL table 3.3 lists GREEN and BLUE as TexImage client formats (GL CTS packed_pixels
 // rgba8_format_green/blue upload with them and verify the readback): the single input component
 // feeds the named channel, the other color channels default to 0 and alpha to 1.
@@ -1317,6 +1377,56 @@ TEST_F(TextureTest, GetTextureImageReadsNamedObjectWithoutBinding) {
     EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
 }
 
+// GL 4.6 core 8.11.4 asks a readback for cube completeness and nothing else, so a mip chain whose
+// levels BELOW the requested one were never defined is still readable at that level - which is
+// exactly the shape ARB_clear_texture's conformance cases build (they define only the level they
+// clear). The whole-chain completeness gate used to answer INVALID_OPERATION here.
+TEST_F(TextureTest, GetTexImageReadsALevelWhoseLowerLevelsWereNeverDefined) {
+    GLuint texture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &texture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, texture);
+
+    const Uint8 pixels[] = {
+        61, 62, 63, 64,
+        71, 72, 73, 74,
+    };
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 2, GL_RGBA8, 2, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    Uint8 output[sizeof(pixels)] = {};
+    MG_Impl::GLImpl::GetTexImage(GL_TEXTURE_2D, 2, GL_RGBA, GL_UNSIGNED_BYTE, output);
+
+    EXPECT_EQ(std::memcmp(output, pixels, sizeof(pixels)), 0);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
+// The other half of the same rule: loosening the chain-wide check must not let a level that holds
+// no image at all through. Level 0 exists as a chain slot once level 2 is defined, but nothing ever
+// gave it an image, so it stays INVALID_OPERATION - as does a level past the end of the chain and a
+// texture that was never given any image whatsoever.
+TEST_F(TextureTest, GetTexImageStillRejectsALevelThatHoldsNoImage) {
+    GLuint texture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &texture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, texture);
+
+    Uint8 output[4] = {};
+
+    // No image at all yet: the chain carries no levels.
+    MG_Impl::GLImpl::GetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, output);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 2, GL_RGBA8, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // Inside the chain, but never defined.
+    MG_Impl::GLImpl::GetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, output);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+
+    // Past the end of the chain.
+    MG_Impl::GLImpl::GetTexImage(GL_TEXTURE_2D, 3, GL_RGBA, GL_UNSIGNED_BYTE, output);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+}
+
 TEST_F(TextureTest, GetTextureSubImageReadsFullNamedLevelWithoutBinding) {
     GLuint texture = 0;
     GLuint boundTexture = 0;
@@ -1651,6 +1761,56 @@ TEST_F(TextureTest, AnUncompressedRespecificationClearsTheCompressedTag) {
     EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
 }
 
+// The same rule for the 3D entry points, which never recorded the tag at all. Besides the two
+// level queries this decides the level's texel BLOCK SIZE, which glCopyImageSubData compares
+// against the other endpoint's - an untagged GL_COMPRESSED_RG_RGTC2 array level measured as the
+// RG8 storage it resolves to, 2 bytes instead of 16.
+TEST_F(TextureTest, TexImage3DAndTexStorage3DTagASpecificCompressedInternalFormat) {
+    GLuint texture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &texture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_ARRAY, texture);
+    MG_Impl::GLImpl::TexImage3D(GL_TEXTURE_2D_ARRAY, 0, GL_COMPRESSED_RG_RGTC2, 8, 8, 2, 0, GL_RG,
+                                GL_UNSIGNED_BYTE, nullptr);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    GLint compressed = GL_FALSE;
+    MG_Impl::GLImpl::GetTexLevelParameteriv(GL_TEXTURE_2D_ARRAY, 0, GL_TEXTURE_COMPRESSED, &compressed);
+    EXPECT_EQ(compressed, GL_TRUE);
+
+    GLint internalFormat = 0;
+    MG_Impl::GLImpl::GetTexLevelParameteriv(GL_TEXTURE_2D_ARRAY, 0, GL_TEXTURE_INTERNAL_FORMAT, &internalFormat);
+    EXPECT_EQ(internalFormat, static_cast<GLint>(GL_COMPRESSED_RG_RGTC2));
+
+    // 8x8 in 4x4 blocks of 16 bytes each is 64 bytes a layer, and both layers count.
+    GLint imageSize = 0;
+    MG_Impl::GLImpl::GetTexLevelParameteriv(GL_TEXTURE_2D_ARRAY, 0, GL_TEXTURE_COMPRESSED_IMAGE_SIZE, &imageSize);
+    EXPECT_EQ(imageSize, 128);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // The texel shadow behind the tag keeps the uncompressed storage the format resolves to.
+    const auto textureObject = MG_State::pGLContext->GetTextureObject(texture);
+    ASSERT_NE(textureObject, nullptr);
+    EXPECT_EQ(textureObject->GetFormat(), TextureInternalFormat::RG8);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_ARRAY, 0);
+
+    // glTexStorage3D has the same gap and the same fix; immutable storage plus
+    // glCompressedTexSubImage3D is the modern way to upload a compressed array texture.
+    GLuint storageTexture = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D_ARRAY, 1, &storageTexture);
+    MG_Impl::GLImpl::TextureStorage3D(storageTexture, 1, GL_COMPRESSED_RG_RGTC2, 8, 8, 2);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_ARRAY, storageTexture);
+
+    compressed = GL_FALSE;
+    MG_Impl::GLImpl::GetTexLevelParameteriv(GL_TEXTURE_2D_ARRAY, 0, GL_TEXTURE_COMPRESSED, &compressed);
+    EXPECT_EQ(compressed, GL_TRUE);
+    imageSize = 0;
+    MG_Impl::GLImpl::GetTexLevelParameteriv(GL_TEXTURE_2D_ARRAY, 0, GL_TEXTURE_COMPRESSED_IMAGE_SIZE, &imageSize);
+    EXPECT_EQ(imageSize, 128);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_ARRAY, 0);
+}
+
 namespace {
     // A 16x16 RGBA8 texture with exactly `levelCount` levels, defined the way
     // KHR-GL43.copy_image.non_existent_mipmap defines its textures - glTexImage2D per
@@ -2975,6 +3135,58 @@ TEST_F(TextureTest, CtsStyleStateResetOnDefaultTexturesLeavesNoError) {
     EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR) << "GL_TEXTURE_2D_MULTISAMPLE_ARRAY reset failed";
 }
 
+// Clean is not enough: per GL 4.6 core 8.8 that zero-sized reset has to DEALLOCATE the image,
+// not define an empty one. gluStateReset runs it on both default multisample textures on every
+// texture unit of a 3.2+ context, and a default texture left 'defined' afterwards stops being
+// skipped by IsUndefinedDefaultTexture - it then joins the per-draw sync and bind passes on
+// every unit the reset touched and reaches an ES glTexStorage*Multisample(..., 0, 0), which ES
+// 3.1 8.19 rejects on every driver.
+TEST_F(TextureTest, ZeroSizedMultisampleTexImageDeallocatesTheImage) {
+    MG_Impl::GLImpl::ActiveTexture(GL_TEXTURE0);
+
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
+    const auto& defaultMultisample = MG_State::pGLContext->GetTextureUnitObject(0)
+                                         .GetBindingSlot(TextureTarget::Texture2DMultisample)
+                                         .GetBoundObject();
+    MG_Impl::GLImpl::TexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 1, GL_RGBA8, 4, 4, GL_TRUE);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    ASSERT_FALSE(MG_State::GLState::IsUndefinedDefaultTexture(defaultMultisample.get()));
+
+    MG_Impl::GLImpl::TexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 1, GL_RGBA8, 0, 0, GL_TRUE);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    EXPECT_TRUE(MG_State::GLState::IsUndefinedDefaultTexture(defaultMultisample.get()));
+
+    // The array target's reset also passes zero LAYERS, which deallocates just the same.
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_MULTISAMPLE_ARRAY, 0);
+    const auto& defaultMultisampleArray = MG_State::pGLContext->GetTextureUnitObject(0)
+                                              .GetBindingSlot(TextureTarget::Texture2DMultisampleArray)
+                                              .GetBoundObject();
+    MG_Impl::GLImpl::TexImage3DMultisample(GL_TEXTURE_2D_MULTISAMPLE_ARRAY, 1, GL_RGBA8, 4, 4, 2, GL_TRUE);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    ASSERT_FALSE(MG_State::GLState::IsUndefinedDefaultTexture(defaultMultisampleArray.get()));
+
+    MG_Impl::GLImpl::TexImage3DMultisample(GL_TEXTURE_2D_MULTISAMPLE_ARRAY, 1, GL_RGBA8, 4, 4, 0, GL_TRUE);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    EXPECT_TRUE(MG_State::GLState::IsUndefinedDefaultTexture(defaultMultisampleArray.get()));
+
+    // The immutable forms do NOT share that leniency: GL 4.6 core 8.19 makes a size below 1
+    // INVALID_VALUE, and freezing an imageless texture as immutable would be unrecoverable.
+    GLuint texture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &texture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_MULTISAMPLE, texture);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+    MG_Impl::GLImpl::TexStorage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, 1, GL_RGBA8, 0, 0, GL_TRUE);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+    EXPECT_FALSE(MG_State::pGLContext->GetTextureUnitObject(0)
+                     .GetBindingSlot(TextureTarget::Texture2DMultisample)
+                     .GetBoundObject()
+                     ->IsImmutable());
+
+    MG_Impl::GLImpl::DeleteTextures(1, &texture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_MULTISAMPLE, 0);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
 // ---- GL CTS packed_pixels / texture_swizzle readback root-cause regressions --------------------
 
 TEST_F(TextureTest, NormalizeLegacySizedFormatsMapToCanonicalShadowLayouts) {
@@ -2985,11 +3197,19 @@ TEST_F(TextureTest, NormalizeLegacySizedFormatsMapToCanonicalShadowLayouts) {
         GLenum type;
     };
     const Case cases[] = {
-        // Legacy <=8-bit-per-channel formats store as UNorm8 component arrays.
-        {GL_R3_G3_B2, GL_RGB565, GL_RGB, GL_UNSIGNED_BYTE},
-        {GL_RGB4, GL_RGB565, GL_RGB, GL_UNSIGNED_BYTE},
-        {GL_RGB5, GL_RGB565, GL_RGB, GL_UNSIGNED_BYTE},
-        {GL_RGBA2, GL_RGBA4, GL_RGBA, GL_UNSIGNED_BYTE},
+        // Legacy <=8-bit-per-channel DESKTOP-ONLY formats store as UNorm8 component arrays, in the
+        // 8-bit-per-channel ES format that layout already is. Storing them in the narrower
+        // GL_RGB565/GL_RGBA4 they nominally fit in made the driver requantize the shadow bytes on
+        // every upload, which is not lossless: 5-bit 2 -> UNorm8 16 -> 16/255*31 = 1.945, which a
+        // truncating driver reads back as 1 (KHR-GL43.copy_image rgb4->rgb4, 12/12 failing on Mali).
+        {GL_R3_G3_B2, GL_RGB8, GL_RGB, GL_UNSIGNED_BYTE},
+        {GL_RGB4, GL_RGB8, GL_RGB, GL_UNSIGNED_BYTE},
+        {GL_RGB5, GL_RGB8, GL_RGB, GL_UNSIGNED_BYTE},
+        {GL_RGBA2, GL_RGBA8, GL_RGBA, GL_UNSIGNED_BYTE},
+        // The two that are ES formats in their own right keep their native storage: an application
+        // that asks for GL_RGBA4 or GL_RGB5_A1 is asking for the smaller image, and the same
+        // normalization also picks the storage for glRenderbufferStorage, where those two are
+        // ordinary ES render targets rather than a desktop-compatibility shim.
         {GL_RGBA4, GL_RGBA4, GL_RGBA, GL_UNSIGNED_BYTE},
         {GL_RGB5_A1, GL_RGB5_A1, GL_RGBA, GL_UNSIGNED_BYTE},
         // 10/12-bit channels store as UNorm16 component arrays.
@@ -3268,6 +3488,29 @@ TEST(SharedExponentRGB9E5Test, RawPackedPixelTransferCoversOnlyIdenticalLayouts)
                                           TexturePixelDataType::UnsignedInt5999Rev));
 }
 
+TEST(SharedExponentRGB9E5Test, RedundantPackedEncodingIsRGB9E5Only) {
+    using MG_Util::PixelStoreProcessor::HasRedundantPackedEncoding;
+
+    // This is the predicate that decides whether the CPU shadow has to answer glGetTexImage
+    // instead of a GPU readback, so it must be as narrow as the defect: only the shared exponent
+    // has several legal encodings of one value.
+    EXPECT_TRUE(HasRedundantPackedEncoding(TextureInternalFormat::RGB9E5));
+
+    // The other three packed 32-bit layouts round-trip through float32 bit-exactly (each field is
+    // either an integer or a unique float encoding), so a GPU readback still serves them - which
+    // matters because RGB10_A2 and R11F_G11F_B10F ARE colour-renderable and their shadow can
+    // legitimately be stale.
+    EXPECT_FALSE(HasRedundantPackedEncoding(TextureInternalFormat::RGB10A2));
+    EXPECT_FALSE(HasRedundantPackedEncoding(TextureInternalFormat::RGB10A2UI));
+    EXPECT_FALSE(HasRedundantPackedEncoding(TextureInternalFormat::R11FG11FB10F));
+
+    // Nothing unpacked qualifies, and neither does an unknown format.
+    EXPECT_FALSE(HasRedundantPackedEncoding(TextureInternalFormat::RGBA8));
+    EXPECT_FALSE(HasRedundantPackedEncoding(TextureInternalFormat::RGBA32F));
+    EXPECT_FALSE(HasRedundantPackedEncoding(TextureInternalFormat::RGB8));
+    EXPECT_FALSE(HasRedundantPackedEncoding(TextureInternalFormat::Unknown));
+}
+
 TEST_F(TextureTest, TexImage2DRGB9E5KeepsNonCanonicalClientWords) {
     // Upload direction: GL_RGB / GL_UNSIGNED_INT_5_9_9_9_REV into GL_RGB9_E5 stores the client
     // words untouched, including the redundant encodings the CTS generates.
@@ -3625,6 +3868,131 @@ TEST_F(TextureTest, ColorAttachableTargetsRequestTheThreeChannelWidening) {
                 PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget);
     EXPECT_FALSE(GetRenderTargetNormalizeOptions(capabilities, texture2DIndex) &
                  PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget);
+
+    // ...and neither can an 8-bit one. That half of the answer used to be missing entirely, which
+    // is why an R8_SNORM / RG8_SNORM colour attachment got no substitute at all on a driver
+    // without EXT_render_snorm.
+    EXPECT_TRUE(GetRenderTargetNormalizeOptions(noSnormCapabilities, texture2DIndex) &
+                PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget);
+    EXPECT_FALSE(GetRenderTargetNormalizeOptions(capabilities, texture2DIndex) &
+                 PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget);
+    EXPECT_FALSE(GetRenderTargetNormalizeOptions(noSnormCapabilities, bufferIndex) &
+                 PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget);
+
+    // 8-bit signed-normalized storage is core ES, so only EXT_render_snorm gates the 8-bit bit;
+    // the 16-bit one also needs EXT_texture_norm16 for the encoding to exist at all.
+    MG_External::GLESCapabilities noNorm16Capabilities{};
+    noNorm16Capabilities.SupportsRenderSnorm = true;
+    noNorm16Capabilities.SupportsNorm16Texture = false;
+    EXPECT_TRUE(GetRenderTargetNormalizeOptions(noNorm16Capabilities, texture2DIndex) &
+                PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget);
+    EXPECT_FALSE(GetRenderTargetNormalizeOptions(noNorm16Capabilities, texture2DIndex) &
+                 PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget);
+}
+
+// ---- Signed-normalized colour-renderable substitution (KHR-GL4x.texture_swizzle on Mali) -------
+//
+// A driver without GL_EXT_render_snorm treats every signed-normalized format as texture-only, so a
+// colour attachment in one of them leaves the ES framebuffer incomplete: the draw lands nowhere and
+// the readback falls through to the CPU shadow, which for a glTexImage2D(..., nullptr) output
+// texture is all zeroes. The render-target bits used to reach GL_RGB16_SNORM alone, so five of the
+// eight SNORM formats - and in particular the single-channel GL_R8_SNORM / GL_R16_SNORM that
+// KHR-GL4x.texture_swizzle renders into for EVERY SNORM source format - had no fallback at all.
+
+TEST_F(TextureTest, SnormRenderTargetOptionsApplyToEverySignedNormalizedFormat) {
+    using MG_Util::TextureFormatProcessor::GetApplicablePixelFormatNormalizeOptions;
+    const Flags<PixelFormatNormalizeOptionBit> requested =
+        PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget | PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget;
+
+    for (const GLenum internalFormat : {GL_R8_SNORM, GL_RG8_SNORM, GL_RGB8_SNORM, GL_RGBA8_SNORM}) {
+        const auto applicable = GetApplicablePixelFormatNormalizeOptions(internalFormat, requested);
+        EXPECT_TRUE(applicable & PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget)
+            << "internalformat 0x" << std::hex << internalFormat;
+        // The two bits are per precision class, so the 16-bit one never reaches an 8-bit format -
+        // that is what keeps the fallback reason from naming both.
+        EXPECT_FALSE(applicable & PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget)
+            << "internalformat 0x" << std::hex << internalFormat;
+    }
+    for (const GLenum internalFormat : {GL_R16_SNORM, GL_RG16_SNORM, GL_RGB16_SNORM, GL_RGBA16_SNORM}) {
+        const auto applicable = GetApplicablePixelFormatNormalizeOptions(internalFormat, requested);
+        EXPECT_TRUE(applicable & PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget)
+            << "internalformat 0x" << std::hex << internalFormat;
+        EXPECT_FALSE(applicable & PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget)
+            << "internalformat 0x" << std::hex << internalFormat;
+    }
+    // GL_RGB16_SNORM used to be granted the 16-bit bit only when the three-channel widening was
+    // requested alongside it, which made the answer depend on the order the caller assembled its
+    // option set in. The capability probe and the runtime storage choice assemble different sets.
+    EXPECT_TRUE(GetApplicablePixelFormatNormalizeOptions(GL_RGB16_SNORM,
+                                                         PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget) &
+                PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget);
+
+    // Nothing else responds to either bit; an unsigned-normalized or float format keeps its storage.
+    for (const GLenum internalFormat : {GL_R8, GL_R16, GL_RGBA8, GL_RGBA16, GL_RGB16F, GL_RGBA32F, GL_RGB9_E5}) {
+        EXPECT_FALSE(GetApplicablePixelFormatNormalizeOptions(internalFormat, requested))
+            << "internalformat 0x" << std::hex << internalFormat;
+    }
+}
+
+TEST_F(TextureTest, SnormRenderTargetSubstitutesKeepEveryChannelValueExactly) {
+    using MG_Util::TextureFormatProcessor::NormalizePixelFormat;
+    struct Case {
+        GLenum requested;
+        Flags<PixelFormatNormalizeOptionBit> options;
+        GLenum internalFormat;
+        GLenum format;
+        GLenum type;
+    };
+    const Flags<PixelFormatNormalizeOptionBit> snorm8RT = PixelFormatNormalizeOptionBit::NoSnorm8RenderTarget;
+    const Flags<PixelFormatNormalizeOptionBit> snorm16RT = PixelFormatNormalizeOptionBit::NoSnorm16RenderTarget;
+
+    const Case cases[] = {
+        // 8-bit: a half float represents every v/127 exactly (the worst case, -123/127, quantizes
+        // 0.03 of a SNORM step away), so it is the same storage GL_RGBA8_SNORM already always got.
+        {GL_R8_SNORM, snorm8RT, GL_R16F, GL_RED, GL_FLOAT},
+        {GL_RG8_SNORM, snorm8RT, GL_RG16F, GL_RG, GL_FLOAT},
+        {GL_RGBA8_SNORM, snorm8RT, GL_RGBA16F, GL_RGBA, GL_FLOAT},
+        // 16-bit: NOT a half float. Its spacing just below 1.0 is some 16 SNORM steps, so it hands
+        // -23451/32767 back as -23457 against a conformance window of one step; a 32-bit float
+        // round-trips all 65535 channel values.
+        {GL_R16_SNORM, snorm16RT, GL_R32F, GL_RED, GL_FLOAT},
+        {GL_RG16_SNORM, snorm16RT, GL_RG32F, GL_RG, GL_FLOAT},
+        {GL_RGBA16_SNORM, snorm16RT, GL_RGBA32F, GL_RGBA, GL_FLOAT},
+        // The render-target bit outranks the narrower fallbacks, whichever way the caller's option
+        // set was assembled: the capability probe folds the driver options in, the runtime storage
+        // choice can see the render-target bit alone, and the two have to pick the same storage.
+        {GL_R16_SNORM, snorm16RT | PixelFormatNormalizeOptionBit::NoNorm16, GL_R32F, GL_RED, GL_FLOAT},
+        {GL_RG16_SNORM, snorm16RT | PixelFormatNormalizeOptionBit::NoSnorm16, GL_RG32F, GL_RG, GL_FLOAT},
+        {GL_RGBA16_SNORM,
+         snorm16RT | PixelFormatNormalizeOptionBit::NoNorm16 | PixelFormatNormalizeOptionBit::NoSnorm16,
+         GL_RGBA32F, GL_RGBA, GL_FLOAT},
+        // The three-channel formats go on through the widening, which outranks everything.
+        {GL_RGB8_SNORM, snorm8RT | PixelFormatNormalizeOptionBit::NoThreeChannelRenderTarget, GL_RGBA16F, GL_RGBA,
+         GL_FLOAT},
+        {GL_RGB16_SNORM, snorm16RT | PixelFormatNormalizeOptionBit::NoThreeChannelRenderTarget, GL_RGBA32F, GL_RGBA,
+         GL_FLOAT},
+        // Control: with EXT_render_snorm neither bit is ever set, so the driver that renders to the
+        // signed-normalized encoding keeps storing it byte for byte. This is the shape Adreno and
+        // llvmpipe take, which is why the substitution is invisible on every gate the project runs.
+        {GL_R8_SNORM, PixelFormatNormalizeOptionBit::None, GL_R8_SNORM, GL_RED, GL_BYTE},
+        {GL_RG8_SNORM, PixelFormatNormalizeOptionBit::None, GL_RG8_SNORM, GL_RG, GL_BYTE},
+        {GL_R16_SNORM, PixelFormatNormalizeOptionBit::None, GL_R16_SNORM, GL_RED, GL_SHORT},
+        {GL_RG16_SNORM, PixelFormatNormalizeOptionBit::None, GL_RG16_SNORM, GL_RG, GL_SHORT},
+        {GL_RGBA16_SNORM, PixelFormatNormalizeOptionBit::None, GL_RGBA16_SNORM, GL_RGBA, GL_SHORT},
+        // ...and the bit for the other precision class does nothing on its own.
+        {GL_R8_SNORM, snorm16RT, GL_R8_SNORM, GL_RED, GL_BYTE},
+        {GL_R16_SNORM, snorm8RT, GL_R16_SNORM, GL_RED, GL_SHORT},
+    };
+
+    for (const auto& testCase : cases) {
+        GLenum internalFormat = 0;
+        GLenum format = 0;
+        GLenum type = 0;
+        NormalizePixelFormat(testCase.requested, testCase.options, &internalFormat, &format, &type);
+        EXPECT_EQ(internalFormat, testCase.internalFormat) << "requested 0x" << std::hex << testCase.requested;
+        EXPECT_EQ(format, testCase.format) << "requested 0x" << std::hex << testCase.requested;
+        EXPECT_EQ(type, testCase.type) << "requested 0x" << std::hex << testCase.requested;
+    }
 }
 
 TEST_F(TextureTest, ThreeChannelRenderTargetOptionAppliesToEveryDeniedThreeChannelFormat) {
@@ -3675,9 +4043,10 @@ TEST_F(TextureTest, ThreeChannelWideningRetargetsInternalFormatAndTransferPairTo
         {GL_RGB16F, widen, GL_RGBA16F, GL_RGBA, GL_HALF_FLOAT},
         {GL_RGB32F, widen, GL_RGBA32F, GL_RGBA, GL_FLOAT},
         // 16-bit SNORM keeps its encoding where EXT_render_snorm can render to it; a half float's
-        // 11-bit mantissa cannot represent a 16-bit SNORM channel exactly.
+        // 11-bit mantissa cannot represent a 16-bit SNORM channel exactly, so the driver that
+        // cannot render to the encoding gets the 32-bit float rather than the half.
         {GL_RGB16_SNORM, widen, GL_RGBA16_SNORM, GL_RGBA, GL_SHORT},
-        {GL_RGB16_SNORM, widenNoSnorm16, GL_RGBA16F, GL_RGBA, GL_FLOAT},
+        {GL_RGB16_SNORM, widenNoSnorm16, GL_RGBA32F, GL_RGBA, GL_FLOAT},
         // 16-bit UNORM and the legacy 10/12-bit formats stored as RGB16.
         {GL_RGB16, widen, GL_RGBA32F, GL_RGBA, GL_FLOAT},
         {GL_RGB10, widen, GL_RGBA32F, GL_RGBA, GL_FLOAT},
@@ -3959,24 +4328,30 @@ TEST_F(TextureTest, CopyTexImage1DReportsUnsupportedInsteadOfTerminating) {
     ExpectSingleGlError(GL_INVALID_OPERATION);
 }
 
-TEST_F(TextureTest, GetTexLevelParameterOnBufferStorageReportsErrorInsteadOfTerminating) {
-    // TextureStorageType is {Mipmap, Buffer} and the level queries only answer out of a mipmap
-    // chain, so every glGetTexLevelParameter* on a GL_TEXTURE_BUFFER texture reached a
-    // THROW_UNIMPL_EXCEPTION default: label and killed the process.
+TEST_F(TextureTest, GetTexLevelParameterAnswersBufferStorageGeometry) {
+    // TextureStorageType is {Mipmap, Buffer} and the level queries used to answer only out of a
+    // mipmap chain, so every glGetTexLevelParameter* on a GL_TEXTURE_BUFFER texture reached a
+    // THROW_UNIMPL_EXCEPTION default: label and killed the process. It now answers out of the
+    // attached buffer range instead (GL 4.6 core 8.9): a buffer texture is one-dimensional, and
+    // with no buffer attached it addresses no texels at all.
     GLuint texture = 0;
     MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_BUFFER, 1, &texture);
     MG_Impl::GLImpl::BindTexture(GL_TEXTURE_BUFFER, texture);
     MG_Impl::GLImpl::TexBuffer(GL_TEXTURE_BUFFER, GL_R8, 0);
     DrainPendingGlErrors();
 
-    for (const GLenum pname : {GL_TEXTURE_WIDTH, GL_TEXTURE_HEIGHT, GL_TEXTURE_DEPTH}) {
+    const std::pair<GLenum, GLint> expectations[] = {
+        {GL_TEXTURE_WIDTH, 0}, {GL_TEXTURE_HEIGHT, 1}, {GL_TEXTURE_DEPTH, 1}};
+    for (const auto& [pname, expected] : expectations) {
         GLint intParam = 0x20202020;
         MG_Impl::GLImpl::GetTexLevelParameteriv(GL_TEXTURE_BUFFER, 0, pname, &intParam);
-        ExpectSingleGlError(GL_INVALID_OPERATION);
+        EXPECT_EQ(MG_Impl::GLImpl::GetError(), static_cast<GLenum>(GL_NO_ERROR));
+        EXPECT_EQ(intParam, expected) << "pname " << pname;
 
         GLfloat floatParam = 12345.0f;
         MG_Impl::GLImpl::GetTexLevelParameterfv(GL_TEXTURE_BUFFER, 0, pname, &floatParam);
-        ExpectSingleGlError(GL_INVALID_OPERATION);
+        EXPECT_EQ(MG_Impl::GLImpl::GetError(), static_cast<GLenum>(GL_NO_ERROR));
+        EXPECT_EQ(floatParam, static_cast<GLfloat>(expected)) << "pname " << pname;
     }
 }
 
@@ -4048,24 +4423,25 @@ namespace {
         GLint SrcZ = -1;
         GLint DstZ = -1;
         GLsizei Depth = -1;
+        Bool SrcIsRenderbuffer = false;
+        Bool DstIsRenderbuffer = false;
     } g_copyImageSubDataCall;
 
-    void RecordCopyImageSubData(const SharedPtr<MG_State::GLState::ITextureObject>& srcTexture, GLenum srcTarget,
+    void RecordCopyImageSubData(const MG_Backend::CopyImageEndpoint& src, GLenum srcTarget,
                                 GLint srcLevel, GLint srcX, GLint srcY, GLint srcZ,
-                                const SharedPtr<MG_State::GLState::ITextureObject>& dstTexture, GLenum dstTarget,
+                                const MG_Backend::CopyImageEndpoint& dst, GLenum dstTarget,
                                 GLint dstLevel, GLint dstX, GLint dstY, GLint dstZ, GLsizei srcWidth,
                                 GLsizei srcHeight, GLsizei srcDepth) {
-        (void)srcTexture;
         (void)srcLevel;
         (void)srcX;
         (void)srcY;
-        (void)dstTexture;
         (void)dstLevel;
         (void)dstX;
         (void)dstY;
         (void)srcWidth;
         (void)srcHeight;
-        g_copyImageSubDataCall = {true, srcTarget, dstTarget, srcZ, dstZ, srcDepth};
+        g_copyImageSubDataCall = {true,   srcTarget, dstTarget,           srcZ,
+                                  dstZ,   srcDepth,  src.IsRenderbuffer(), dst.IsRenderbuffer()};
     }
 
     // Two storage-backed 2D textures of the requested formats, so a copy between them is a legal
@@ -4302,9 +4678,13 @@ TEST_F(TextureTest, CopyImageSubDataAcceptsAPlainMutableTexImage2DPair) {
     MG_Impl::GLImpl::GenTextures(1, &reusedSrc);
     MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, reusedSrc);
     MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
     MG_Impl::GLImpl::GenTextures(1, &reusedDst);
     MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, reusedDst);
     MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
     ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
 
     MG_Impl::GLImpl::CopyImageSubData(reusedSrc, GL_TEXTURE_2D, 0, 0, 0, 0, reusedDst, GL_TEXTURE_2D, 0, 0, 0, 0, 1,
@@ -4336,3 +4716,476 @@ TEST_F(TextureTest, CopyImageSubDataPassesTheRectangleTargetThroughUntranslated)
     EXPECT_EQ(g_copyImageSubDataCall.DstTarget, static_cast<GLenum>(GL_TEXTURE_RECTANGLE));
     EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
 }
+
+// GL 4.6 core 18.3.2 accepts GL_RENDERBUFFER as an endpoint target, and a renderbuffer name lives
+// in its own namespace. Resolving BOTH names through the texture namespace answered a null object
+// for every renderbuffer endpoint, so all 74 conformance cases that name one - the whole
+// texture<->renderbuffer half of KHR-GL43.copy_image, plus its smoke test - reported
+// GL_INVALID_VALUE. The endpoint is a sum type now; the target picks the namespace.
+TEST_F(TextureTest, CopyImageSubDataResolvesARenderbufferEndpointInTheRenderbufferNamespace) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint texture = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D, 1, &texture);
+    MG_Impl::GLImpl::TextureStorage2D(texture, 1, GL_RGBA8, 8, 8);
+    GLuint renderbuffer = 0;
+    MG_Impl::GLImpl::CreateRenderbuffers(1, &renderbuffer);
+    MG_Impl::GLImpl::NamedRenderbufferStorage(renderbuffer, GL_RGBA8, 8, 8);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::CopyImageSubData(texture, GL_TEXTURE_2D, 0, 0, 0, 0, renderbuffer, GL_RENDERBUFFER, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_FALSE(g_copyImageSubDataCall.SrcIsRenderbuffer);
+    EXPECT_TRUE(g_copyImageSubDataCall.DstIsRenderbuffer);
+    EXPECT_EQ(g_copyImageSubDataCall.DstTarget, static_cast<GLenum>(GL_RENDERBUFFER));
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // ...and back the other way, which is the second half of the conformance case's two-copy
+    // shape (texture -> renderbuffer -> texture).
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(renderbuffer, GL_RENDERBUFFER, 0, 0, 0, 0, texture, GL_TEXTURE_2D, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_TRUE(g_copyImageSubDataCall.SrcIsRenderbuffer);
+    EXPECT_FALSE(g_copyImageSubDataCall.DstIsRenderbuffer);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
+// Renderbuffer to renderbuffer, the shape neither endpoint could take before, plus the negative
+// that pins which table was consulted: with GL_RENDERBUFFER named, a number that is not a live
+// RENDERBUFFER is INVALID_VALUE - the texture table is never asked.
+TEST_F(TextureTest, CopyImageSubDataKeepsTheTwoNameNamespacesApart) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint srcRenderbuffer = 0;
+    GLuint dstRenderbuffer = 0;
+    MG_Impl::GLImpl::CreateRenderbuffers(1, &srcRenderbuffer);
+    MG_Impl::GLImpl::CreateRenderbuffers(1, &dstRenderbuffer);
+    MG_Impl::GLImpl::NamedRenderbufferStorage(srcRenderbuffer, GL_RGBA8, 8, 8);
+    MG_Impl::GLImpl::NamedRenderbufferStorage(dstRenderbuffer, GL_RGBA8, 8, 8);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::CopyImageSubData(srcRenderbuffer, GL_RENDERBUFFER, 0, 0, 0, 0, dstRenderbuffer,
+                                      GL_RENDERBUFFER, 0, 0, 0, 0, 4, 4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_TRUE(g_copyImageSubDataCall.SrcIsRenderbuffer);
+    EXPECT_TRUE(g_copyImageSubDataCall.DstIsRenderbuffer);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcRenderbuffer, GL_RENDERBUFFER, 0, 0, 0, 0, 4243, GL_RENDERBUFFER, 0, 0, 0,
+                                      0, 4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+}
+
+// A renderbuffer has exactly one image, so any level above zero is the same INVALID_VALUE a
+// texture gets for a level it does not have - and an unallocated one is an incomplete image,
+// which 18.3.2 spells INVALID_OPERATION.
+TEST_F(TextureTest, CopyImageSubDataChecksARenderbufferLevelAndStorage) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint texture = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D, 1, &texture);
+    MG_Impl::GLImpl::TextureStorage2D(texture, 1, GL_RGBA8, 8, 8);
+    GLuint renderbuffer = 0;
+    MG_Impl::GLImpl::CreateRenderbuffers(1, &renderbuffer);
+    MG_Impl::GLImpl::NamedRenderbufferStorage(renderbuffer, GL_RGBA8, 8, 8);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::CopyImageSubData(texture, GL_TEXTURE_2D, 0, 0, 0, 0, renderbuffer, GL_RENDERBUFFER, 1, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+
+    g_copyImageSubDataCall = {};
+    GLuint emptyRenderbuffer = 0;
+    MG_Impl::GLImpl::CreateRenderbuffers(1, &emptyRenderbuffer);
+    DrainPendingGlErrors();
+
+    MG_Impl::GLImpl::CopyImageSubData(texture, GL_TEXTURE_2D, 0, 0, 0, 0, emptyRenderbuffer, GL_RENDERBUFFER, 0, 0,
+                                      0, 0, 4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+}
+
+// GL 4.6 core 18.3.2 requires INVALID_VALUE when the region exceeds either image's boundaries, and
+// this validator had no bounds check whatsoever: the one call shaped like one,
+// ValidateCopyImageBlockAlignment, returns true on its first line for every UNCOMPRESSED format.
+// Texture endpoints only looked covered because the ES driver raised its own error - which
+// DirectGLES logs and swallows, so the application saw GL_NO_ERROR and a destination that never
+// changed (KHR-GL43.copy_image.exceeding_boundaries).
+TEST_F(TextureTest, CopyImageSubDataRejectsARegionThatLeavesTheImage) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint srcTexture = 0;
+    GLuint dstTexture = 0;
+    MakeCopyImagePair(GL_RGBA8, GL_RGBA8, srcTexture, dstTexture);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // The region that exactly reaches the far edge is the boundary this must NOT reject - a
+    // validator that answered INVALID_VALUE to every non-origin region would satisfy the negatives
+    // below and break every legal partial copy.
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D, 0, 4, 4, 0, dstTexture, GL_TEXTURE_2D, 0, 4, 4, 0,
+                                      4, 4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // One texel past it on x, on y, and on the destination side.
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D, 0, 5, 4, 0, dstTexture, GL_TEXTURE_2D, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D, 0, 4, 5, 0, dstTexture, GL_TEXTURE_2D, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D, 0, 0, 0, 0, dstTexture, GL_TEXTURE_2D, 0, 5, 5, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+
+    // A negative origin is out of bounds on the other side of the same rule.
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D, 0, -1, 0, 0, dstTexture, GL_TEXTURE_2D, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+}
+
+// The endpoint the missing bounds check actually cost: a renderbuffer never reaches the ES
+// driver's texture-shaped checks either, so a 4x4 region at y = 14 of a 16x16 renderbuffer - the
+// exact sub-case KHR-GL43.copy_image.exceeding_boundaries starts with, GL_RENDERBUFFER being first
+// in its target list - was accepted outright.
+TEST_F(TextureTest, CopyImageSubDataBoundsARenderbufferRegion) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint texture = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D, 1, &texture);
+    MG_Impl::GLImpl::TextureStorage2D(texture, 1, GL_RGBA8, 16, 16);
+    GLuint renderbuffer = 0;
+    MG_Impl::GLImpl::CreateRenderbuffers(1, &renderbuffer);
+    MG_Impl::GLImpl::NamedRenderbufferStorage(renderbuffer, GL_RGBA8, 16, 16);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::CopyImageSubData(renderbuffer, GL_RENDERBUFFER, 0, 0, 12, 0, texture, GL_TEXTURE_2D, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(renderbuffer, GL_RENDERBUFFER, 0, 0, 14, 0, texture, GL_TEXTURE_2D, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+
+    // ...and as the destination, where the same renderbuffer has the same one image.
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(texture, GL_TEXTURE_2D, 0, 0, 0, 0, renderbuffer, GL_RENDERBUFFER, 0, 14, 0, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+
+    // A renderbuffer has exactly one slice, so any z at all is out of range.
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(renderbuffer, GL_RENDERBUFFER, 0, 0, 0, 1, texture, GL_TEXTURE_2D, 0, 0, 0, 0,
+                                      4, 4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+}
+
+// The z axis was structurally unbounded - srcZ/dstZ did not even reach the validator - so a layer
+// range running off the end of an array reached the backend as an out-of-range image subresource.
+TEST_F(TextureTest, CopyImageSubDataBoundsTheLayerRangeOfAnArray) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint srcTexture = 0;
+    GLuint dstTexture = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D_ARRAY, 1, &srcTexture);
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D_ARRAY, 1, &dstTexture);
+    MG_Impl::GLImpl::TextureStorage3D(srcTexture, 1, GL_RGBA8, 8, 8, 12);
+    MG_Impl::GLImpl::TextureStorage3D(dstTexture, 1, GL_RGBA8, 8, 8, 12);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // Layers 5..11 of a 12-layer array: the last one the range may reach.
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D_ARRAY, 0, 0, 0, 5, dstTexture, GL_TEXTURE_2D_ARRAY,
+                                      0, 0, 0, 5, 4, 4, 7);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D_ARRAY, 0, 0, 0, 6, dstTexture, GL_TEXTURE_2D_ARRAY,
+                                      0, 0, 0, 0, 4, 4, 7);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_2D_ARRAY, 0, 0, 0, 0, dstTexture, GL_TEXTURE_2D_ARRAY,
+                                      0, 0, 0, 6, 4, 4, 7);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+}
+
+// The convention the bounds check has to get right, and the one that would silently reject legal
+// copies if it did not: on a CUBE MAP the z axis selects among the six faces, which this frontend
+// keeps as six separate one-slice upload targets - so the level's own extent reports depth 1 and a
+// bound taken from it would refuse every whole-cube copy.
+TEST_F(TextureTest, CopyImageSubDataCountsCubeMapFacesOnTheZAxis) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint srcTexture = 0;
+    GLuint dstTexture = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_CUBE_MAP, 1, &srcTexture);
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_CUBE_MAP, 1, &dstTexture);
+    MG_Impl::GLImpl::TextureStorage2D(srcTexture, 1, GL_RGBA8, 8, 8);
+    MG_Impl::GLImpl::TextureStorage2D(dstTexture, 1, GL_RGBA8, 8, 8);
+    DrainPendingGlErrors();
+
+    const auto srcObject = MG_State::pGLContext->GetTextureObject(srcTexture);
+    const auto dstObject = MG_State::pGLContext->GetTextureObject(dstTexture);
+    ASSERT_NE(srcObject, nullptr);
+    ASSERT_NE(dstObject, nullptr);
+    if (!srcObject->IsComplete() || !dstObject->IsComplete()) {
+        GTEST_SKIP() << "this context could not give the cube maps storage";
+    }
+
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_CUBE_MAP, 0, 0, 0, 0, dstTexture, GL_TEXTURE_CUBE_MAP,
+                                      0, 0, 0, 0, 8, 8, 6);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    // A seventh face does not exist.
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_CUBE_MAP, 0, 0, 0, 1, dstTexture, GL_TEXTURE_CUBE_MAP,
+                                      0, 0, 0, 0, 8, 8, 6);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+}
+
+// The other axis convention: GL puts a 1D ARRAY's layers on y for this entry point (srcY is the
+// first layer, srcHeight the layer count), which is also where this frontend keeps them - so the
+// level extent answers directly and z stays a single slice.
+TEST_F(TextureTest, CopyImageSubDataBoundsA1DArraysLayersOnTheYAxis) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint srcTexture = 0;
+    GLuint dstTexture = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_1D_ARRAY, 1, &srcTexture);
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_1D_ARRAY, 1, &dstTexture);
+    MG_Impl::GLImpl::TextureStorage2D(srcTexture, 1, GL_RGBA8, 16, 8);
+    MG_Impl::GLImpl::TextureStorage2D(dstTexture, 1, GL_RGBA8, 16, 8);
+    DrainPendingGlErrors();
+
+    const auto srcObject = MG_State::pGLContext->GetTextureObject(srcTexture);
+    const auto dstObject = MG_State::pGLContext->GetTextureObject(dstTexture);
+    ASSERT_NE(srcObject, nullptr);
+    ASSERT_NE(dstObject, nullptr);
+    if (!srcObject->IsComplete() || !dstObject->IsComplete()) {
+        GTEST_SKIP() << "this context could not give the 1D arrays storage";
+    }
+
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_1D_ARRAY, 0, 0, 3, 0, dstTexture, GL_TEXTURE_1D_ARRAY,
+                                      0, 0, 3, 0, 4, 5, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(srcTexture, GL_TEXTURE_1D_ARRAY, 0, 0, 4, 0, dstTexture, GL_TEXTURE_1D_ARRAY,
+                                      0, 0, 0, 0, 4, 5, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_VALUE);
+}
+
+// A 16-byte RGTC2 block and a 16-byte RGBA32UI texel are in the same size class, so GL 4.6 core
+// 18.3.2 requires this copy to succeed. It did not for an ARRAY source: glTexImage3D recorded no
+// specific-compressed-format tag, so the level was measured as the 2-byte RG8 storage RGTC2
+// resolves to and the compatibility rule saw 2 against 16.
+TEST_F(TextureTest, CopyImageSubDataSizesACompressedArrayLevelByItsBlock) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint compressedSource = 0;
+    MG_Impl::GLImpl::GenTextures(1, &compressedSource);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_ARRAY, compressedSource);
+    MG_Impl::GLImpl::TexImage3D(GL_TEXTURE_2D_ARRAY, 0, GL_COMPRESSED_RG_RGTC2, 8, 8, 1, 0, GL_RG,
+                                GL_UNSIGNED_BYTE, nullptr);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_BASE_LEVEL, 0);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D_ARRAY, GL_TEXTURE_MAX_LEVEL, 0);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D_ARRAY, 0);
+
+    GLuint uncompressedDestination = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D_ARRAY, 1, &uncompressedDestination);
+    MG_Impl::GLImpl::TextureStorage3D(uncompressedDestination, 1, GL_RGBA32UI, 8, 8, 1);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::CopyImageSubData(compressedSource, GL_TEXTURE_2D_ARRAY, 0, 0, 0, 0, uncompressedDestination,
+                                      GL_TEXTURE_2D_ARRAY, 0, 0, 0, 0, 8, 8, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
+// 18.3.2 requires INVALID_OPERATION when either object is an INCOMPLETE TEXTURE, and completeness
+// is GL 4.6 core 8.17's - which includes the mip chain whenever the minification filter reads it.
+// A mutable texture with level 0 alone still carries the default NEAREST_MIPMAP_LINEAR filter, so
+// it is mipmap incomplete; the storage-only IsComplete() this used to ask called it complete and
+// let the copy through, which is the whole of KHR-GL43.copy_image.incomplete_tex.
+TEST_F(TextureTest, CopyImageSubDataRejectsAMipmapIncompleteTexture) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint incomplete = 0;
+    MG_Impl::GLImpl::GenTextures(1, &incomplete);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, incomplete);
+    MG_Impl::GLImpl::TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, 0);
+    GLuint complete = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D, 1, &complete);
+    MG_Impl::GLImpl::TextureStorage2D(complete, 1, GL_RGBA8, 16, 16);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::CopyImageSubData(incomplete, GL_TEXTURE_2D, 0, 0, 0, 0, complete, GL_TEXTURE_2D, 0, 0, 0, 0, 4,
+                                      4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+
+    // The destination side is checked the same way.
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::CopyImageSubData(complete, GL_TEXTURE_2D, 0, 0, 0, 0, incomplete, GL_TEXTURE_2D, 0, 0, 0, 0, 4,
+                                      4, 1);
+    EXPECT_FALSE(g_copyImageSubDataCall.Called);
+    ExpectSingleGlError(GL_INVALID_OPERATION);
+
+    // Capping TEXTURE_MAX_LEVEL at the one level that exists is what the conformance suite's
+    // makeTextureComplete does, and it is enough to make the same object complete.
+    g_copyImageSubDataCall = {};
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, incomplete);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
+    MG_Impl::GLImpl::TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, 0);
+    DrainPendingGlErrors();
+
+    MG_Impl::GLImpl::CopyImageSubData(incomplete, GL_TEXTURE_2D, 0, 0, 0, 0, complete, GL_TEXTURE_2D, 0, 0, 0, 0, 4,
+                                      4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
+// The targets that have no mip chain must not be dragged in: GL 4.6 core 8.17 makes q equal to
+// level_base for them, so no filter can make them mipmap incomplete. A rectangle texture gets a
+// non-mipmapping default filter from the object itself, so it would survive a predicate that
+// trusted the sampler alone - it is here because the whole texture path is one branch and this is
+// the cheap half of pinning it.
+TEST_F(TextureTest, CopyImageSubDataDoesNotApplyMipmapCompletenessToRectangleTextures) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint srcRectangle = 0;
+    GLuint dstRectangle = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_RECTANGLE, 1, &srcRectangle);
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_RECTANGLE, 1, &dstRectangle);
+    MG_Impl::GLImpl::TextureStorage2D(srcRectangle, 1, GL_RGBA8, 8, 8);
+    MG_Impl::GLImpl::TextureStorage2D(dstRectangle, 1, GL_RGBA8, 8, 8);
+    ASSERT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::CopyImageSubData(srcRectangle, GL_TEXTURE_RECTANGLE, 0, 0, 0, 0, dstRectangle,
+                                      GL_TEXTURE_RECTANGLE, 0, 0, 0, 0, 4, 4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
+// The multisample half, which is the one the target guard actually exists for: a multisample
+// texture keeps the shared NEAREST_MIPMAP_LINEAR default in its own sampler state (only the
+// rectangle constructor overrides it), so asking the mipmap predicate about it without the target
+// guard would report every 8x8 multisample image incomplete and refuse a legal copy.
+TEST_F(TextureTest, CopyImageSubDataDoesNotApplyMipmapCompletenessToMultisampleTextures) {
+    const ScopedTextureBackendFunctionsOverride backendGuard;
+    MG_Backend::gBackendFunctionsTable.GL.CopyImageSubData = RecordCopyImageSubData;
+    g_copyImageSubDataCall = {};
+
+    GLuint srcMultisample = 0;
+    GLuint dstMultisample = 0;
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D_MULTISAMPLE, 1, &srcMultisample);
+    MG_Impl::GLImpl::CreateTextures(GL_TEXTURE_2D_MULTISAMPLE, 1, &dstMultisample);
+    MG_Impl::GLImpl::TextureStorage2DMultisample(srcMultisample, 1, GL_RGBA8, 8, 8, GL_FALSE);
+    MG_Impl::GLImpl::TextureStorage2DMultisample(dstMultisample, 1, GL_RGBA8, 8, 8, GL_FALSE);
+    DrainPendingGlErrors();
+
+    // This unit-test binary has no backend behind the renderable-format and sample-count queries,
+    // so the storage may not have been created at all. Checked on the state objects rather than
+    // assumed, so the case can only skip or test the real rule.
+    const auto srcObject = MG_State::pGLContext->GetTextureObject(srcMultisample);
+    const auto dstObject = MG_State::pGLContext->GetTextureObject(dstMultisample);
+    ASSERT_NE(srcObject, nullptr);
+    ASSERT_NE(dstObject, nullptr);
+    if (!srcObject->IsComplete() || !dstObject->IsComplete()) {
+        GTEST_SKIP() << "this context could not give the multisample textures storage";
+    }
+
+    MG_Impl::GLImpl::CopyImageSubData(srcMultisample, GL_TEXTURE_2D_MULTISAMPLE, 0, 0, 0, 0, dstMultisample,
+                                      GL_TEXTURE_2D_MULTISAMPLE, 0, 0, 0, 0, 4, 4, 1);
+    EXPECT_TRUE(g_copyImageSubDataCall.Called);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+}
+
+// GL 4.6 core 8.11 makes GL_IMAGE_FORMAT_COMPATIBILITY_TYPE readable through every
+// GetTexParameter form. Three of MobileGL's four getters answered it and glGetTexParameterfv did
+// not, so the float query raised GL_INVALID_ENUM and left the caller's float uninitialised
+// (KHR-GL4x.shader_image_load_store.basic-api-texParam reads it with both iv and fv and compares
+// them). Asserted across all four here, because an enum present in three of four parallel
+// switches is the drift shape that comes back.
+TEST_F(TextureTest, ImageFormatCompatibilityTypeAgreesAcrossEveryTexParameterGetter) {
+    GLuint texture = 0;
+    MG_Impl::GLImpl::GenTextures(1, &texture);
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, texture);
+    MG_Impl::GLImpl::TexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, 4, 4);
+    DrainPendingGlErrors();
+
+    GLint integerValue = 0;
+    MG_Impl::GLImpl::GetTexParameteriv(GL_TEXTURE_2D, GL_IMAGE_FORMAT_COMPATIBILITY_TYPE, &integerValue);
+    EXPECT_EQ(integerValue, GL_IMAGE_FORMAT_COMPATIBILITY_BY_SIZE);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    GLfloat floatValue = 0.0f;
+    MG_Impl::GLImpl::GetTexParameterfv(GL_TEXTURE_2D, GL_IMAGE_FORMAT_COMPATIBILITY_TYPE, &floatValue);
+    EXPECT_FLOAT_EQ(floatValue, static_cast<GLfloat>(GL_IMAGE_FORMAT_COMPATIBILITY_BY_SIZE));
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    GLint signedValue = 0;
+    MG_Impl::GLImpl::GetTexParameterIiv(GL_TEXTURE_2D, GL_IMAGE_FORMAT_COMPATIBILITY_TYPE, &signedValue);
+    EXPECT_EQ(signedValue, GL_IMAGE_FORMAT_COMPATIBILITY_BY_SIZE);
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    GLuint unsignedValue = 0;
+    MG_Impl::GLImpl::GetTexParameterIuiv(GL_TEXTURE_2D, GL_IMAGE_FORMAT_COMPATIBILITY_TYPE, &unsignedValue);
+    EXPECT_EQ(unsignedValue, static_cast<GLuint>(GL_IMAGE_FORMAT_COMPATIBILITY_BY_SIZE));
+    EXPECT_EQ(MG_Impl::GLImpl::GetError(), GL_NO_ERROR);
+
+    MG_Impl::GLImpl::BindTexture(GL_TEXTURE_2D, 0);
+    MG_Impl::GLImpl::DeleteTextures(1, &texture);
+    DrainPendingGlErrors();
+}

MobileGL/MG_Util/BackendLoaders/OpenGL/Loader.cpp

@@ -692,8 +692,12 @@ namespace MobileGL::MG_Util::BackendLoader {
             !f.glUnmapBuffer || !f.glMemoryBarrier || !f.glCreateShader || !f.glCreateProgram) {
             return false;
         }
-        GLint maxVertexSsboBlocks = 0;
-        f.glGetIntegerv(GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS, &maxVertexSsboBlocks);
+        // Read from caps, not re-queried: the per-stage limits are resolved (and their query
+        // errors drained) before this probe runs, so asking the driver again would be a second
+        // round trip that can disagree with the number MobileGL actually advertises - and, on
+        // the early return below, would leave its own GL_INVALID_ENUM in the queue for the
+        // application's first glGetError to find.
+        const GLint maxVertexSsboBlocks = caps.MaxVertexShaderStorageBlocks;
         if (maxVertexSsboBlocks < 1) {
             // The native indirect machinery cannot read the command buffer from the vertex
             // stage on this driver anyway; assume conforming zero-based gl_InstanceID.
@@ -827,6 +831,35 @@ namespace MobileGL::MG_Util::BackendLoader {
         return includesBase;
     }
 
+    // GL 4.6 table 23.65 admits exactly four answers for GL_LAYER_PROVOKING_VERTEX and
+    // GL_VIEWPORT_INDEX_PROVOKING_VERTEX. Anything else means the driver wrote something MobileGL
+    // cannot forward as a convention, and GL_UNDEFINED_VERTEX - a legal answer, not a placeholder
+    // - is the accurate thing to say about it.
+    static GLenum NormalizeProvokingVertexConvention(GLint driverValue) {
+        switch (static_cast<GLenum>(driverValue)) {
+        case GL_FIRST_VERTEX_CONVENTION:
+        case GL_LAST_VERTEX_CONVENTION:
+        case GL_PROVOKING_VERTEX:
+        case GL_UNDEFINED_VERTEX:
+            return static_cast<GLenum>(driverValue);
+        default:
+            return GL_UNDEFINED_VERTEX;
+        }
+    }
+
+    static const char* ProvokingVertexConventionName(GLenum convention) {
+        switch (convention) {
+        case GL_FIRST_VERTEX_CONVENTION:
+            return "GL_FIRST_VERTEX_CONVENTION";
+        case GL_LAST_VERTEX_CONVENTION:
+            return "GL_LAST_VERTEX_CONVENTION";
+        case GL_PROVOKING_VERTEX:
+            return "GL_PROVOKING_VERTEX";
+        default:
+            return "GL_UNDEFINED_VERTEX";
+        }
+    }
+
     Bool FillInGLESCapabilities(MG_External::GLESCapabilities& caps, const MG_External::GLESFunctionsTable& glesFuncs) {
         if (!glesFuncs.glGetString || !glesFuncs.glGetIntegerv) {
             MGLOG_E("Required GLES functions are not loaded, cannot query capabilities");
@@ -932,6 +965,9 @@ namespace MobileGL::MG_Util::BackendLoader {
                 if (std::strcmp(extension, "GL_EXT_clip_cull_distance") == 0) {
                     caps.SupportsClipDistance = true;
                 }
+                if (std::strcmp(extension, "GL_OES_viewport_array") == 0) {
+                    caps.SupportsViewportArray = true;
+                }
             }
         }
         // The pointer check on top of the extension check makes each flag sufficient on its own
@@ -989,6 +1025,8 @@ namespace MobileGL::MG_Util::BackendLoader {
         MGLOG_I("    base instance (EXT_base_instance; emulated by attribute offsets when absent): %s",
                 caps.SupportsBaseInstance ? "yes" : "no");
         MGLOG_I("    clip distances (EXT_clip_cull_distance): %s", caps.SupportsClipDistance ? "yes" : "no");
+        MGLOG_I("    viewport array (OES_viewport_array; gl_ViewportIndex collapses to viewport 0 when absent): %s",
+                caps.SupportsViewportArray ? "yes" : "no");
 
         // LOAD-BEARING STRING, not just a banner. android-plugin/trace-replay-ci.sh's
         // is_angle_surface_lost() greps mobilegl.log for exactly "OpenGL ES capabilities:" to
@@ -1031,6 +1069,15 @@ namespace MobileGL::MG_Util::BackendLoader {
         GLint maxVertexAttribs = 16;
         GLint maxComputeShaderStorageBlocks = 8;
         GLint maxCombinedShaderStorageBlocks = 32;
+        // ES 3.2 table 21.44 minimums. Zero for the four graphics stages below fragment is not a
+        // placeholder - it is what the spec permits and what ARM's GLES driver actually reports,
+        // so a probe that never runs (pre-ES 3.2, unsupported pname) leaves behind the truthful
+        // answer rather than an optimistic one.
+        GLint maxVertexShaderStorageBlocks = 0;
+        GLint maxTessControlShaderStorageBlocks = 0;
+        GLint maxTessEvaluationShaderStorageBlocks = 0;
+        GLint maxGeometryShaderStorageBlocks = 0;
+        GLint maxFragmentShaderStorageBlocks = 4;
         GLint maxComputeUniformBlocks = 12;
         GLint maxComputeWorkGroupInvocations = 128;
         GLint maxShaderStorageBufferBindings = 8;
@@ -1045,8 +1092,21 @@ namespace MobileGL::MG_Util::BackendLoader {
         GLint maxComputeImageUniforms = 8;
         GLint maxDrawBuffers = 8;
         GLint maxColorAttachments = 8;
-        GLint maxClipDistances = 8;
+        // Zero is a legal answer, not a placeholder. GL_MAX_CLIP_DISTANCES exists in ES only as
+        // GL_MAX_CLIP_DISTANCES_EXT under GL_EXT_clip_cull_distance, so on a driver without that
+        // extension there is nowhere to put a clip distance at all: SPIRV-Cross emits
+        // gl_ClipDistance behind an `#extension ... : require` the ESSL compiler rejects, and
+        // DirectGLES has no state to forward the per-distance enables into (see the gate in
+        // DirectGLES::SyncRenderState). Starting at 8 meant a probe that could never run left an
+        // optimistic 8 behind, so the frontend promised eight clip planes and every draw with a
+        // clipping program silently rendered nothing. The guarded probe below only ever widens it.
+        GLint maxClipDistances = 0;
         GLint maxViewports = 16;
+        // GL_UNDEFINED_VERTEX is what stands when the probes below cannot run, and it is a legal
+        // answer rather than a placeholder: with neither geometry shaders nor a viewport array
+        // there is no layered or multi-viewport draw for a convention to describe.
+        GLenum layerProvokingVertex = GL_UNDEFINED_VERTEX;
+        GLenum viewportIndexProvokingVertex = GL_UNDEFINED_VERTEX;
         GLfloat minFragmentInterpolationOffset = -0.5f;
         GLfloat maxFragmentInterpolationOffset = 0.4375f;
         GLint fragmentInterpolationOffsetBits = 4;
@@ -1056,11 +1116,39 @@ namespace MobileGL::MG_Util::BackendLoader {
         GLint maxProgramTextureGatherOffset = 7;
         GLint maxPatchVertices = 32;
         GLint maxTessGenLevel = 64;
+        // Function-scope, and used by every probe group below rather than redeclared inside each
+        // one. Returns whether anything was drained, which is what lets a group tell "the driver
+        // answered" from "the driver rejected the pname and left my local alone".
+        const auto drainErrors = [&glesFuncs]() {
+            Bool hadError = false;
+            if (glesFuncs.glGetError) {
+                while (glesFuncs.glGetError() != GL_NO_ERROR) hadError = true;
+            }
+            return hadError;
+        };
+
+        // THE GENERATOR OF THIS WHOLE BUG FAMILY, closed here. A bare glGetIntegerv/glGetFloatv
+        // of a pname the driver does not have does two damaging things at once: it leaves the
+        // local at whatever the declaration initialised it to - an optimistic number the frontend
+        // then advertises as a capability - and it leaves a GL_INVALID_ENUM in the queue where
+        // the next unrelated probe's caller, or the application's first glGetError, gets blamed
+        // for it. The per-stage storage block, fragment interpolation and buffer texture probes
+        // below already drain and fall back; this unconditional run did neither, which is how
+        // GL_MAX_CLIP_DISTANCES came to be advertised as 8 on a driver with no clip distances at
+        // all. Every pname here that is not ES core is now either gated on the capability that
+        // makes it exist or floored at the value a rejected probe would have left, and the whole
+        // run is bracketed by a drain.
+        drainErrors();
         glesFuncs.glGetFloatv(GL_ALIASED_LINE_WIDTH_RANGE, aliasedLineWidthRange);
+        // GL_SMOOTH_LINE_WIDTH_RANGE / GL_SMOOTH_LINE_WIDTH_GRANULARITY (0x0B22 / 0x0B23) are
+        // desktop-only - ES has never had an antialiased line width query - so on a real GLES
+        // driver these two raise GL_INVALID_ENUM. Kept as probes rather than dropped because the
+        // ANGLE and desktop-GL hosts MobileGL also runs on do answer them; the initialisers are
+        // the GL 4.6 table 23.55 minimum of [1, 1], which is both the honest answer for a driver
+        // that cannot say and what an untouched out-param already holds.
         glesFuncs.glGetFloatv(GL_SMOOTH_LINE_WIDTH_RANGE, smoothLineWidthRange);
         glesFuncs.glGetFloatv(GL_SMOOTH_LINE_WIDTH_GRANULARITY, &smoothLineWidthGranularity);
         glesFuncs.glGetFloatv(GL_ALIASED_POINT_SIZE_RANGE, aliasedPointSizeRange);
-        glesFuncs.glGetFloatv(GL_VIEWPORT_BOUNDS_RANGE, viewportBoundsRange);
         glesFuncs.glGetIntegerv(GL_MAX_3D_TEXTURE_SIZE, &max3DTextureSize);
         glesFuncs.glGetIntegerv(GL_MAX_ARRAY_TEXTURE_LAYERS, &maxArrayTextureLayers);
         glesFuncs.glGetIntegerv(GL_MAX_CUBE_MAP_TEXTURE_SIZE, &maxCubeMapTextureSize);
@@ -1084,8 +1172,25 @@ namespace MobileGL::MG_Util::BackendLoader {
         // single test case. 1 is a spec-legal value (the minimum required), so cap
         // to what is actually implemented instead of forwarding the raw driver limit.
         maxSampleMaskWords = std::min(maxSampleMaskWords, 1);
+        // The multisample ceilings above are ES 3.1 state apart from GL_MAX_SAMPLES, which is ES
+        // 3.0, so a 3.0 context rejects five of the six and leaves whatever the out-param held.
+        // One sample is what a rejected probe leaves behind and is also the smallest legal
+        // answer, so clamp rather than trust: a zero reaching GL_Getter would have the frontend
+        // reject the very sample count it just advertised (see GetAdvertisedMaxSamples).
+        maxColorTextureSamples = std::max(maxColorTextureSamples, 1);
+        maxDepthTextureSamples = std::max(maxDepthTextureSamples, 1);
+        maxFramebufferSamples = std::max(maxFramebufferSamples, 1);
+        maxIntegerSamples = std::max(maxIntegerSamples, 1);
+        maxSamples = std::max(maxSamples, 1);
+        maxSampleMaskWords = std::max(maxSampleMaskWords, 1);
+        // ES 3.2 core, or EXT_tessellation_shader on 3.1. Probed rather than version-gated so a
+        // 3.1 driver that HAS the extension still gets to answer; the clamp below is what makes a
+        // rejected query safe, since GL 4.6 table 23.66 and ES 3.2 table 21.45 set the same
+        // minimums the initialisers carry and neither API permits less.
         glesFuncs.glGetIntegerv(GL_MAX_PATCH_VERTICES, &maxPatchVertices);
         glesFuncs.glGetIntegerv(GL_MAX_TESS_GEN_LEVEL, &maxTessGenLevel);
+        maxPatchVertices = std::max(maxPatchVertices, 32);
+        maxTessGenLevel = std::max(maxTessGenLevel, 64);
         glesFuncs.glGetIntegerv(GL_MIN_PROGRAM_TEXTURE_GATHER_OFFSET, &minProgramTextureGatherOffset);
         glesFuncs.glGetIntegerv(GL_MAX_PROGRAM_TEXTURE_GATHER_OFFSET, &maxProgramTextureGatherOffset);
         // A driver that leaves the probe untouched (pre-ES 3.1, or an ignored enum) must not
@@ -1122,21 +1227,121 @@ namespace MobileGL::MG_Util::BackendLoader {
             (caps.GLESVersion.Major == 3 && caps.GLESVersion.Minor >= 2)) {
             glesFuncs.glGetIntegerv(GL_MAX_GEOMETRY_IMAGE_UNIFORMS, &maxGeometryImageUniforms);
         }
+        // Closes the bracket opened before the run: every local above now holds either the
+        // driver's answer or a floor, and nothing this function asked for is left in the error
+        // queue for a later probe - or the application - to be blamed for.
+        if (drainErrors()) {
+            MGLOG_W("One or more capability queries were rejected by this driver; the affected "
+                    "limits keep MobileGL's spec-minimum floors");
+        }
+        // Per-stage storage-block counts. Deliberately NOT batched with the unconditional probes
+        // above, for the reason GL_MAX_TEXTURE_BUFFER_SIZE is not: the vertex and fragment pnames
+        // are ES 3.1, but the tessellation and geometry ones only exist from ES 3.2 on (or under
+        // EXT_tessellation_shader / EXT_geometry_shader), so on an older context they raise
+        // GL_INVALID_ENUM, leave the local untouched, and - with nothing draining the queue until
+        // some later probe - let that error be misattributed to an unrelated query in between, or
+        // leak into the application's first glGetError.
+        //
+        // A stage whose probe does not run keeps the spec minimum, which for all four graphics
+        // stages is 0. That is the honest answer: DirectGLES emits ESSL 3.10 on an ES 3.1 context,
+        // where those stages do not exist at all.
+        {
+            // Isolate from errors raised by the preceding probes so the drain below reports on
+            // these queries only.
+            drainErrors();
+            glesFuncs.glGetIntegerv(GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS, &maxVertexShaderStorageBlocks);
+            glesFuncs.glGetIntegerv(GL_MAX_FRAGMENT_SHADER_STORAGE_BLOCKS, &maxFragmentShaderStorageBlocks);
+            if (drainErrors()) {
+                MGLOG_W("Per-stage shader storage block query failed for the vertex/fragment "
+                        "stages; assuming the ES minimums (vertex 0, fragment 4)");
+                maxVertexShaderStorageBlocks = 0;
+                maxFragmentShaderStorageBlocks = 4;
+            }
+            if (esAtLeast32) {
+                glesFuncs.glGetIntegerv(GL_MAX_TESS_CONTROL_SHADER_STORAGE_BLOCKS,
+                                        &maxTessControlShaderStorageBlocks);
+                glesFuncs.glGetIntegerv(GL_MAX_TESS_EVALUATION_SHADER_STORAGE_BLOCKS,
+                                        &maxTessEvaluationShaderStorageBlocks);
+                glesFuncs.glGetIntegerv(GL_MAX_GEOMETRY_SHADER_STORAGE_BLOCKS, &maxGeometryShaderStorageBlocks);
+                if (drainErrors()) {
+                    MGLOG_W("Per-stage shader storage block query failed for the tessellation/"
+                            "geometry stages; assuming the ES minimum of 0");
+                    maxTessControlShaderStorageBlocks = 0;
+                    maxTessEvaluationShaderStorageBlocks = 0;
+                    maxGeometryShaderStorageBlocks = 0;
+                }
+            }
+            // A driver is free to report a negative or nonsensical count into an untouched
+            // out-param; clamp before anything downstream treats it as a capacity.
+            maxVertexShaderStorageBlocks = std::max(maxVertexShaderStorageBlocks, 0);
+            maxTessControlShaderStorageBlocks = std::max(maxTessControlShaderStorageBlocks, 0);
+            maxTessEvaluationShaderStorageBlocks = std::max(maxTessEvaluationShaderStorageBlocks, 0);
+            maxGeometryShaderStorageBlocks = std::max(maxGeometryShaderStorageBlocks, 0);
+            maxFragmentShaderStorageBlocks = std::max(maxFragmentShaderStorageBlocks, 0);
+        }
         glesFuncs.glGetIntegerv(GL_MAX_DRAW_BUFFERS, &maxDrawBuffers);
         glesFuncs.glGetIntegerv(GL_MAX_COLOR_ATTACHMENTS, &maxColorAttachments);
-        glesFuncs.glGetIntegerv(GL_MAX_CLIP_DISTANCES, &maxClipDistances);
-        glesFuncs.glGetIntegerv(GL_MAX_VIEWPORTS, &maxViewports);
+        // GL_MAX_CLIP_DISTANCES is 0x0D32, which ES only ever spells GL_MAX_CLIP_DISTANCES_EXT and
+        // only ever has under GL_EXT_clip_cull_distance. The extension was already resolved into
+        // caps.SupportsClipDistance a few hundred lines above and is the same flag DirectGLES
+        // gates the CLIP_DISTANCEi enable forwarding on, so ask the driver only where the pname
+        // exists; everywhere else the honest 0 stands and no GL_INVALID_ENUM is left behind for an
+        // unrelated query - or the application's first glGetError - to trip over.
+        if (caps.SupportsClipDistance) {
+            drainErrors();
+            glesFuncs.glGetIntegerv(GL_MAX_CLIP_DISTANCES, &maxClipDistances);
+            if (drainErrors()) {
+                MGLOG_W("GL_EXT_clip_cull_distance is advertised but GL_MAX_CLIP_DISTANCES was "
+                        "rejected; reporting no clip distances");
+                maxClipDistances = 0;
+            }
+        }
         glesFuncs.glGetIntegerv(GL_MAX_VIEWPORT_DIMS, maxViewportDims);
-        glesFuncs.glGetIntegerv(GL_VIEWPORT_SUBPIXEL_BITS, &viewportSubpixelBits);
+        // GL_LAYER_PROVOKING_VERTEX is ES 3.2 core (it arrives with geometry shaders, which is
+        // what gl_Layer needs). Ask the driver where the pname exists rather than asserting a
+        // convention: it is a statement about which vertex of a primitive supplies gl_Layer, and
+        // MobileGL forwards the geometry stage to the driver rather than implementing the
+        // selection itself, so the driver's answer IS MobileGL's answer. Below ES 3.2 there are
+        // no layered draws to have a convention for and GL_UNDEFINED_VERTEX stands, which GL 4.6
+        // table 23.65 explicitly permits.
+        if (esAtLeast32) {
+            GLint driverLayerConvention = static_cast<GLint>(GL_UNDEFINED_VERTEX);
+            drainErrors();
+            glesFuncs.glGetIntegerv(GL_LAYER_PROVOKING_VERTEX, &driverLayerConvention);
+            if (!drainErrors()) {
+                layerProvokingVertex = NormalizeProvokingVertexConvention(driverLayerConvention);
+            }
+        }
+        // GL_MAX_VIEWPORTS (0x825B), GL_VIEWPORT_SUBPIXEL_BITS (0x825C) and GL_VIEWPORT_BOUNDS_RANGE
+        // (0x825D) all arrive with GL_OES_viewport_array and exist nowhere in ES core, so on the
+        // drivers DirectGLES actually runs on all three raise GL_INVALID_ENUM. The values MobileGL
+        // advertises do not change by asking: GL_Getter answers GL_MAX_VIEWPORTS from the frontend
+        // state width (indexed viewport entry points validate against RenderStateParameters::
+        // MAX_VIEWPORTS, so a device answer of 1 would reject indices the state can legitimately
+        // hold), floors GL_SUBPIXEL_BITS at its own 4, and the bounds range is clamped to the core
+        // minimum below. What changes is that the errors stop being manufactured.
+        if (caps.SupportsViewportArray) {
+            GLint driverViewportIndexConvention = static_cast<GLint>(GL_UNDEFINED_VERTEX);
+            drainErrors();
+            glesFuncs.glGetIntegerv(GL_MAX_VIEWPORTS, &maxViewports);
+            glesFuncs.glGetIntegerv(GL_VIEWPORT_SUBPIXEL_BITS, &viewportSubpixelBits);
+            glesFuncs.glGetIntegerv(GL_VIEWPORT_INDEX_PROVOKING_VERTEX, &driverViewportIndexConvention);
+            if (glesFuncs.glGetFloatv) {
+                glesFuncs.glGetFloatv(GL_VIEWPORT_BOUNDS_RANGE, viewportBoundsRange);
+            }
+            if (drainErrors()) {
+                MGLOG_W("GL_OES_viewport_array is advertised but its viewport limit queries were "
+                        "rejected; keeping the OpenGL core minimums");
+                maxViewports = 16;
+                viewportSubpixelBits = 0;
+                viewportBoundsRange[0] = -32768.0f;
+                viewportBoundsRange[1] = 32767.0f;
+            } else {
+                viewportIndexProvokingVertex =
+                    NormalizeProvokingVertexConvention(driverViewportIndexConvention);
+            }
+        }
         if (caps.SupportsShaderMultisampleInterpolation && glesFuncs.glGetFloatv) {
-            const auto drainErrors = [&glesFuncs]() {
-                Bool hadError = false;
-                if (glesFuncs.glGetError) {
-                    while (glesFuncs.glGetError() != GL_NO_ERROR) hadError = true;
-                }
-                return hadError;
-            };
-
             // Isolate these optional queries from errors raised by preceding capability
             // probes, then consume any query error so initialization never leaks it into
             // the application's first glGetError call.
@@ -1266,6 +1471,11 @@ namespace MobileGL::MG_Util::BackendLoader {
         caps.MaxVertexAttribs = maxVertexAttribs;
         caps.MaxComputeShaderStorageBlocks = maxComputeShaderStorageBlocks;
         caps.MaxCombinedShaderStorageBlocks = maxCombinedShaderStorageBlocks;
+        caps.MaxVertexShaderStorageBlocks = maxVertexShaderStorageBlocks;
+        caps.MaxTessControlShaderStorageBlocks = maxTessControlShaderStorageBlocks;
+        caps.MaxTessEvaluationShaderStorageBlocks = maxTessEvaluationShaderStorageBlocks;
+        caps.MaxGeometryShaderStorageBlocks = maxGeometryShaderStorageBlocks;
+        caps.MaxFragmentShaderStorageBlocks = maxFragmentShaderStorageBlocks;
         caps.MaxComputeUniformBlocks = maxComputeUniformBlocks;
         caps.MaxComputeWorkGroupInvocations = maxComputeWorkGroupInvocations;
         caps.MaxShaderStorageBufferBindings = maxShaderStorageBufferBindings;
@@ -1292,8 +1502,12 @@ namespace MobileGL::MG_Util::BackendLoader {
         caps.MaxComputeImageUniforms = maxComputeImageUniforms;
         caps.MaxDrawBuffers = maxDrawBuffers;
         caps.MaxColorAttachments = maxColorAttachments;
-        caps.MaxClipDistances = maxClipDistances;
+        // A driver is free to write nonsense into an out-param it then rejects, and without the
+        // extension the probe above never ran at all - so the flag, not the local, decides.
+        caps.MaxClipDistances = caps.SupportsClipDistance ? std::max(maxClipDistances, 0) : 0;
         caps.MaxViewports = maxViewports;
+        caps.LayerProvokingVertex = layerProvokingVertex;
+        caps.ViewportIndexProvokingVertex = viewportIndexProvokingVertex;
         caps.MaxViewportWidth = maxViewportDims[0];
         caps.MaxViewportHeight = maxViewportDims[1];
         // Only ever WIDER than the core minimum: a driver that answered the query is allowed to
@@ -1343,6 +1557,14 @@ namespace MobileGL::MG_Util::BackendLoader {
         MGLOG_I("    GL_MAX_VERTEX_ATTRIBS: %d", caps.MaxVertexAttribs);
         MGLOG_I("    GL_MAX_COMPUTE_SHADER_STORAGE_BLOCKS: %d", caps.MaxComputeShaderStorageBlocks);
         MGLOG_I("    GL_MAX_COMBINED_SHADER_STORAGE_BLOCKS: %d", caps.MaxCombinedShaderStorageBlocks);
+        // Worth a line each: a zero here is what stops an application's storage block from ever
+        // working in that stage, and reading it back from an artifact is the difference between
+        // "MobileGL dropped my draw" and "this driver has no SSBOs outside compute".
+        MGLOG_I("    GL_MAX_VERTEX_SHADER_STORAGE_BLOCKS: %d", caps.MaxVertexShaderStorageBlocks);
+        MGLOG_I("    GL_MAX_TESS_CONTROL_SHADER_STORAGE_BLOCKS: %d", caps.MaxTessControlShaderStorageBlocks);
+        MGLOG_I("    GL_MAX_TESS_EVALUATION_SHADER_STORAGE_BLOCKS: %d", caps.MaxTessEvaluationShaderStorageBlocks);
+        MGLOG_I("    GL_MAX_GEOMETRY_SHADER_STORAGE_BLOCKS: %d", caps.MaxGeometryShaderStorageBlocks);
+        MGLOG_I("    GL_MAX_FRAGMENT_SHADER_STORAGE_BLOCKS: %d", caps.MaxFragmentShaderStorageBlocks);
         MGLOG_I("    GL_MAX_COMPUTE_UNIFORM_BLOCKS: %d", caps.MaxComputeUniformBlocks);
         MGLOG_I("    GL_MAX_COMPUTE_WORK_GROUP_INVOCATIONS: %d", caps.MaxComputeWorkGroupInvocations);
         MGLOG_I("    GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS: %d", caps.MaxShaderStorageBufferBindings);
@@ -1366,12 +1588,20 @@ namespace MobileGL::MG_Util::BackendLoader {
         MGLOG_I("    GL_MAX_COMPUTE_IMAGE_UNIFORMS: %d", caps.MaxComputeImageUniforms);
         MGLOG_I("    GL_MAX_DRAW_BUFFERS: %d", caps.MaxDrawBuffers);
         MGLOG_I("    GL_MAX_COLOR_ATTACHMENTS: %d", caps.MaxColorAttachments);
-        MGLOG_I("    GL_MAX_CLIP_DISTANCES: %d", caps.MaxClipDistances);
+        // Worth spelling the reason out for the same reason the per-stage storage block counts
+        // are: a zero here is what stops an application's gl_ClipDistance from ever clipping, and
+        // reading it back from an artifact is the difference between "MobileGL dropped my draw"
+        // and "this driver has no clip distances".
+        MGLOG_I("    GL_MAX_CLIP_DISTANCES: %d%s", caps.MaxClipDistances,
+                caps.SupportsClipDistance ? "" : " (no GL_EXT_clip_cull_distance on this driver)");
         MGLOG_I("    GL_MAX_VIEWPORTS: %d", caps.MaxViewports);
         MGLOG_I("    GL_MAX_VIEWPORT_DIMS: [%d, %d]", caps.MaxViewportWidth, caps.MaxViewportHeight);
         MGLOG_I("    GL_VIEWPORT_BOUNDS_RANGE: [%.3f, %.3f]", caps.ViewportBoundsRangeMin,
                 caps.ViewportBoundsRangeMax);
         MGLOG_I("    GL_VIEWPORT_SUBPIXEL_BITS: %d", caps.ViewportSubpixelBits);
+        MGLOG_I("    GL_LAYER_PROVOKING_VERTEX: %s", ProvokingVertexConventionName(caps.LayerProvokingVertex));
+        MGLOG_I("    GL_VIEWPORT_INDEX_PROVOKING_VERTEX: %s",
+                ProvokingVertexConventionName(caps.ViewportIndexProvokingVertex));
 
         caps.IndirectDrawInstanceIdIncludesBaseInstance =
             ProbeIndirectInstanceIdIncludesBaseInstance(caps, glesFuncs);
@@ -1395,6 +1625,14 @@ namespace MobileGL::MG_Util::BackendLoader {
                 caps.AvoidSamplerMipmapMinFilter ? "true" : "false");
         MGLOG_I("    Avoid explicit LOD bias: %s", caps.AvoidExplicitLodBias ? "true" : "false");
 
+        // Last line of defence. Capability init is the very first thing that touches the driver,
+        // so anything it leaves in the error queue surfaces at the APPLICATION's first
+        // glGetError and gets attributed to whatever call the app happened to make. Every group
+        // above drains its own, but a probe added later must not be able to reintroduce the leak.
+        if (drainErrors()) {
+            MGLOG_W("Capability initialization left a GL error behind; it has been consumed so it "
+                    "cannot surface at the application's first glGetError");
+        }
         return true;
     }
 } // namespace MobileGL::MG_Util::BackendLoader

MobileGL/MG_Util/BackendLoaders/OpenGL/Loader.h

@@ -1182,6 +1182,21 @@ namespace MobileGL {
             // compile and the per-distance enables have nowhere to go - clipping silently never
             // happens, which is exactly what KHR-GLxx.clip_distance.functional catches.
             Bool SupportsClipDistance = false;
+            // GL_OES_viewport_array is present: the driver knows gl_ViewportIndex in ESSL - and
+            // only then. ESSL has no core spelling for it at ANY version, while SPIRV-Cross prints
+            // the identifier bare and requests nothing for it (contrast gl_Layer, which it backs
+            // with GL_NV_viewport_array2 on ES), so the `#extension GL_OES_viewport_array :
+            // require` line has to be inserted into the emitted source - see
+            // RequestViewportArrayExtension. Without the extension the stage does not compile at
+            // all and the whole program becomes unusable, which on DirectGLES means every draw
+            // using it silently renders nothing; LowerViewportIndexPass is the fallback that
+            // demotes the builtin so the program still links and degrades to viewport 0.
+            //
+            // Extension string only, deliberately: DirectGLES does not call any of the indexed
+            // OES entry points yet, so there is no pointer to require. When that forwarding lands
+            // this must gain the pointer check as well - the rule everywhere else in this struct,
+            // because eglGetProcAddress can hand back a stub that silently drops every call.
+            Bool SupportsViewportArray = false;
             // GL_RENDERER contains "ANGLE".
             Bool IsAngleRenderer = false;
             // GL_RENDERER contains both "ANGLE" and "llvmpipe".
@@ -1233,6 +1248,17 @@ namespace MobileGL {
             Int MaxVertexAttribs = 16;
             Int MaxComputeShaderStorageBlocks = 8;
             Int MaxCombinedShaderStorageBlocks = 32;
+            // Per-stage GL_MAX_*_SHADER_STORAGE_BLOCKS as the host GLES driver reports them.
+            // The defaults are the ES 3.2 minimums (table 21.44): 0 for every graphics stage
+            // except fragment, which is 4. ES only gained the tessellation and geometry pnames
+            // in 3.2 (or with EXT_tessellation_shader / EXT_geometry_shader), so those two are
+            // queried behind a support check and left at the default otherwise - see
+            // FillInGLESCapabilities.
+            Int MaxVertexShaderStorageBlocks = 0;
+            Int MaxTessControlShaderStorageBlocks = 0;
+            Int MaxTessEvaluationShaderStorageBlocks = 0;
+            Int MaxGeometryShaderStorageBlocks = 0;
+            Int MaxFragmentShaderStorageBlocks = 4;
             Int MaxComputeUniformBlocks = 12;
             Int MaxComputeWorkGroupInvocations = 128;
             Int MaxShaderStorageBufferBindings = 8;
@@ -1249,8 +1275,16 @@ namespace MobileGL {
             Int MaxComputeImageUniforms = 8;
             Int MaxDrawBuffers = 8;
             Int MaxColorAttachments = 8;
-            Int MaxClipDistances = 8;
+            // Zero is a legal answer, not a placeholder: ES reaches clip distances only through
+            // GL_EXT_clip_cull_distance, so a driver without it has none. See the guarded probe
+            // in FillInGLESCapabilities.
+            Int MaxClipDistances = 0;
             Int MaxViewports = 16;
+            // GL_LAYER_PROVOKING_VERTEX (ES 3.2 core) and GL_VIEWPORT_INDEX_PROVOKING_VERTEX
+            // (GL_OES_viewport_array). GL_UNDEFINED_VERTEX is a legal answer for both and is what
+            // a driver that has neither is honestly saying.
+            GLenum LayerProvokingVertex = GL_UNDEFINED_VERTEX;
+            GLenum ViewportIndexProvokingVertex = GL_UNDEFINED_VERTEX;
             Int MaxViewportWidth = 16384;
             Int MaxViewportHeight = 16384;
             Float ViewportBoundsRangeMin = 0.0f;

MobileGL/MG_Util/BackendLoaders/Vulkan/Loader.cpp

@@ -237,6 +237,7 @@ namespace MobileGL::MG_Util::BackendLoader {
             supportedFeatures.vertexPipelineStoresAndAtomics == VK_TRUE;
         caps.SupportsFragmentStoresAndAtomics = supportedFeatures.fragmentStoresAndAtomics == VK_TRUE;
         caps.SupportsGeometryShader = supportedFeatures.geometryShader == VK_TRUE;
+        caps.SupportsShaderClipDistance = supportedFeatures.shaderClipDistance == VK_TRUE;
         caps.MaxShaderStorageBlockSize = static_cast<SizeT>(p.limits.maxStorageBufferRange);
         const Bool supportsShaderSubgroup = vk.vkGetPhysicalDeviceProperties2 &&
                                             HasUsableShaderSubgroupSupport(subgroupProps);
@@ -331,6 +332,7 @@ namespace MobileGL::MG_Util::BackendLoader {
         caps.SupportsVertexPipelineStoresAndAtomics = false;
         caps.SupportsFragmentStoresAndAtomics = false;
         caps.SupportsGeometryShader = false;
+        caps.SupportsShaderClipDistance = false;
         caps.MaxShaderStorageBlockSize = static_cast<SizeT>(properties.limits.maxStorageBufferRange);
         caps.SupportsShaderSubgroup = false;
         caps.SubgroupSize = 0;

MobileGL/MG_Util/BackendLoaders/Vulkan/Loader.h

@@ -96,6 +96,12 @@ namespace MobileGL {
             Bool SupportsVertexPipelineStoresAndAtomics = false;
             Bool SupportsFragmentStoresAndAtomics = false;
             Bool SupportsGeometryShader = false;
+            // VkPhysicalDeviceFeatures::shaderClipDistance. maxClipDistances is a LIMIT and is
+            // reported whatever the feature says, so the limit alone does not mean a module may
+            // declare ClipDistance - VulkanRenderer enables the feature only where the physical
+            // device has it, and without it a shader writing gl_ClipDistance is invalid. Very
+            // widely supported, hence read from the device features and never assumed false.
+            Bool SupportsShaderClipDistance = false;
             SizeT MaxShaderStorageBlockSize = 128 * 1024 * 1024;
             Bool SupportsShaderSubgroup = false;
             Uint32 SubgroupSize = 0;

MobileGL/MG_Util/Converters/GLToMG/TextureEnumConverter.cpp

@@ -253,6 +253,12 @@ namespace MobileGL {
                 return TextureInternalFormat::Depth32FStencil8;
             case GL_STENCIL_INDEX8:
                 return TextureInternalFormat::StencilIndex8;
+            // The unsized stencil base format resolves to the only stencil storage there is, the
+            // same way the unsized colour and depth base formats below resolve to theirs. Returning
+            // Unknown made glTexImage2D(GL_STENCIL_INDEX) an error, which killed the negative
+            // clear-texture cases in their own setup before they could reach the call they test.
+            case GL_STENCIL_INDEX:
+                return TextureInternalFormat::StencilIndex8;
             case GL_DEPTH_COMPONENT:
                 return TextureInternalFormat::DepthComponent;
             case GL_DEPTH_STENCIL:

MobileGL/MG_Util/Converters/MGToMG/TextureEnumConverter.cpp

@@ -124,6 +124,9 @@ namespace MobileGL {
             case TextureInternalFormat::DepthComponent32F:
             case TextureInternalFormat::Depth24Stencil8:
             case TextureInternalFormat::Depth32FStencil8:
+            // Already sized: both GL_STENCIL_INDEX8 and the unsized GL_STENCIL_INDEX resolve here,
+            // and there is only one stencil storage to infer.
+            case TextureInternalFormat::StencilIndex8:
                 return internalformat;
             // probably we should assume unorm here?
             case TextureInternalFormat::RGBA: {

MobileGL/MG_Util/SelfTest/DriverPost.cpp

@@ -521,9 +521,11 @@ namespace MobileGL::MG_Util::SelfTest {
             builder.Warn("64-bit vertex attributes",
                          "not supported (ES has no GL_DOUBLE vertex format, and after the fp64 demotion "
                          "above there is no 64-bit shader input left to feed either); "
-                         "glVertexAttribLFormat / glVertexArrayAttribLFormat report "
-                         "GL_INVALID_OPERATION - feed the attribute with glVertexAttribPointer(GL_FLOAT), "
-                         "which a demoted dvec input reads correctly");
+                         "glVertexAttribLFormat / glVertexArrayAttribLFormat succeed and their state is "
+                         "queryable, but an ENABLED 64-bit array is DROPPED at draw and the attribute "
+                         "reads its generic current value - feed the attribute with "
+                         "glVertexAttribPointer(GL_FLOAT) instead, which a demoted dvec input reads "
+                         "correctly");
             if (glesFuncs.glPatchParameteri != nullptr) {
                 builder.Pass("Tessellation patch parameters",
                              "glPatchParameteri present (GL_PATCH_VERTICES reaches the driver)");
@@ -556,8 +558,9 @@ namespace MobileGL::MG_Util::SelfTest {
             } else {
                 builder.Warn("GL_EXT_render_snorm",
                              "not supported; signed-normalized formats are texture-only, so every SNORM "
-                             "render target is stored as a float (GL_RGBA8_SNORM/GL_RGB8_SNORM -> "
-                             "GL_RGBA16F) and its fragment outputs are clamped to [-1,1] in software");
+                             "render target is stored as a float (8-bit -> *16F, 16-bit -> *32F, which "
+                             "is the narrowest float that still holds a 16-bit SNORM channel exactly) "
+                             "and its fragment outputs are clamped to [-1,1] in software");
             }
             // FAIL, not WARN: ES 3.x core makes every float format texture-only, and every Iris
             // shaderpack renders into at least GL_R11F_G11F_B10F (Complementary's colortex0, BSL's
@@ -2336,8 +2339,10 @@ namespace MobileGL::MG_Util::SelfTest {
         builder.Warn("64-bit vertex attributes",
                      "not supported; there is no 64-bit shader input left to feed after the fp64 demotion "
                      "above, and no VK_FORMAT_R64*_SFLOAT vertex fetch to feed it with on most devices "
-                     "anyway. glVertexAttribLFormat reports GL_INVALID_OPERATION - feed the attribute with "
-                     "glVertexAttribPointer(GL_FLOAT), which a demoted dvec input reads correctly");
+                     "anyway. glVertexAttribLFormat succeeds and its state is queryable, but an ENABLED "
+                     "64-bit array is DROPPED at pipeline build and the attribute reads its generic "
+                     "current value - feed the attribute with glVertexAttribPointer(GL_FLOAT) instead, "
+                     "which a demoted dvec input reads correctly");
 
         Bool shaderDrawParameters = false;
         if (vkGetPhysicalDeviceFeatures2Fn != nullptr && properties.apiVersion >= VK_API_VERSION_1_1) {

MobileGL/MG_Util/ShaderTranspiler/CompileEnv.cpp

@@ -28,6 +28,9 @@ namespace MobileGL::MG_Util::ShaderTranspiler {
         HashValue(state, env.maxComputeWorkGroupSize[0]);
         HashValue(state, env.maxComputeWorkGroupSize[1]);
         HashValue(state, env.maxComputeWorkGroupSize[2]);
+        HashValue(state, env.maxComputeWorkGroupCount[0]);
+        HashValue(state, env.maxComputeWorkGroupCount[1]);
+        HashValue(state, env.maxComputeWorkGroupCount[2]);
         HashValue(state, env.maxComputeWorkGroupInvocations);
         HashValue(state, env.backend);
         // DynamicBackendParameters is a plain aggregate of scalars; hashing its object
@@ -41,6 +44,51 @@ namespace MobileGL::MG_Util::ShaderTranspiler {
         return state;
     }
 
+    Uint64 ComputeFrontendCompileEnvFingerprint(const CompileEnv& env) {
+        Uint64 state = 0xff51afd7ed558ccdull;
+        // The DynamicBackendParameters limits BuildTBuiltInResource copies into
+        // TBuiltInResource. Enumerated ONE BY ONE rather than hashed as a struct,
+        // deliberately: hashing all of DynamicBackendParameters would drag ~50 backend-only
+        // limits into a key that is supposed to be backend-agnostic, and every one of them
+        // would be a false miss. Keep this list in step with BuildTBuiltInResource.
+        HashValue(state, env.params.MaxImageUnits);
+        HashValue(state, env.params.MaxDrawBuffers);
+        HashValue(state, env.params.MaxVertexImageUniforms);
+        HashValue(state, env.params.MaxGeometryImageUniforms);
+        HashValue(state, env.params.MaxFragmentImageUniforms);
+        HashValue(state, env.params.MaxComputeImageUniforms);
+        HashValue(state, env.params.MaxCombinedImageUniforms);
+        // Added when wave3 (cb155c5b) made this one env-derived. It expands into the
+        // gl_MaxComputeTextureImageUnits built-in constant, so a compute module that reads
+        // that constant generates DIFFERENT SPIR-V under two backends that disagree on it.
+        HashValue(state, env.params.MaxComputeTextureImageUnits);
+        // Added when wave4 (4fc3531d) made this one env-derived, and the same class again:
+        // glslang REJECTS gl_ClipDistance[i] for i >= maxClipDistances at parse (ParseHelper)
+        // and expands gl_MaxClipDistances from the same number, so it decides both whether a
+        // shader compiles at all and what a module that reads the constant generates.
+        HashValue(state, env.params.MaxClipDistances);
+        // The compute work-group limits, likewise added by wave3 (cb155c5b). They used to be
+        // hardcoded maxima in BuildTBuiltInResource, and the L1 key comment said in so many
+        // words that the day they became backend-derived they would have to move in here -
+        // that day is this merge. glslang expands BOTH of them into built-in constants
+        // (Initialize.cpp: "const ivec3 gl_MaxComputeWorkGroupCount = ivec3(%d,%d,%d)" and the
+        // same for gl_MaxComputeWorkGroupSize), so this is an INDEPENDENCE break, not merely a
+        // reachability one: a compute shader that reads gl_MaxComputeWorkGroupSize compiles to
+        // materially different SPIR-V on a driver reporting z=64 than on one reporting z=1024.
+        for (Uint index = 0; index < 3; ++index) {
+            HashValue(state, env.maxComputeWorkGroupSize[index]);
+            HashValue(state, env.maxComputeWorkGroupCount[index]);
+        }
+        // The two inputs to GetReflectionVertexAttribLimit. Hashed as inputs rather than as
+        // the resolved limit so this stays in one translation unit; that is coarser (two
+        // envs whose MaxVertexAttribs both exceed the storage capacity resolve to the same
+        // limit yet hash differently) but coarser means a false MISS, never a false hit.
+        HashValue(state, env.params.MaxVertexAttribs);
+        const Uint8 hasBackend = env.HasBackend() ? 1u : 0u;
+        HashValue(state, hasBackend);
+        return state;
+    }
+
     SharedPtr<const CompileEnv> CaptureCompileEnv() {
         auto env = MakeShared<CompileEnv>();
 
@@ -51,19 +99,23 @@ namespace MobileGL::MG_Util::ShaderTranspiler {
             env->advertisedExtensions = activeBackend->GetRendererInfo().RendererGLInfo.Extensions;
         }
 
-        // GL_MAX_COMPUTE_WORK_GROUP_SIZE. This is a REAL driver call on DirectGLES; it must
-        // happen here, on the context thread, and exactly once per context. The frontend
-        // minimum is the floor, matching what GL_Getter reports.
-        // TODO: Share these exposed compute limit helpers with GL_Getter.cpp instead of duplicating the frontend minima.
-        constexpr Uint kFrontendMinComputeWorkGroupSizes[3] = {1024, 1024, 64};
+        // GL_MAX_COMPUTE_WORK_GROUP_SIZE / _COUNT. These are REAL driver calls on DirectGLES; they
+        // must happen here, on the context thread, and exactly once per context. The frontend
+        // minimum is the floor, matching what GL_Getter reports - both sides now floor at the
+        // shared MIN_COMPUTE_WORK_GROUP_* constants rather than at their own copy of them.
         for (Uint index = 0; index < 3; ++index) {
-            Int backendValue = 0;
+            Int backendSize = 0;
+            Int backendCount = 0;
             if (MG_Backend::gBackendFunctionsTable.GL.GetIntegeri_v) {
                 MG_Backend::gBackendFunctionsTable.GL.GetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_SIZE, index,
-                                                                    &backendValue);
+                                                                    &backendSize);
+                MG_Backend::gBackendFunctionsTable.GL.GetIntegeri_v(GL_MAX_COMPUTE_WORK_GROUP_COUNT, index,
+                                                                    &backendCount);
             }
             env->maxComputeWorkGroupSize[index] =
-                std::max(static_cast<Uint>(std::max(backendValue, 0)), kFrontendMinComputeWorkGroupSizes[index]);
+                std::max(static_cast<Uint>(std::max(backendSize, 0)), MIN_COMPUTE_WORK_GROUP_SIZE[index]);
+            env->maxComputeWorkGroupCount[index] =
+                std::max(static_cast<Uint>(std::max(backendCount, 0)), MIN_COMPUTE_WORK_GROUP_COUNT[index]);
         }
 
         constexpr Uint64 kFrontendMaxComputeWorkGroupInvocations = 1024;
@@ -73,6 +125,7 @@ namespace MobileGL::MG_Util::ShaderTranspiler {
                           : kFrontendMaxComputeWorkGroupInvocations;
 
         env->fingerprint = ComputeCompileEnvFingerprint(*env);
+        env->frontendFingerprint = ComputeFrontendCompileEnvFingerprint(*env);
         return env;
     }
 
@@ -82,6 +135,7 @@ namespace MobileGL::MG_Util::ShaderTranspiler {
         static const SharedPtr<const CompileEnv> kDefault = [] {
             auto env = MakeShared<CompileEnv>();
             env->fingerprint = ComputeCompileEnvFingerprint(*env);
+            env->frontendFingerprint = ComputeFrontendCompileEnvFingerprint(*env);
             return SharedPtr<const CompileEnv>(Move(env));
         }();
         return kDefault;