diff --git a/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.cpp b/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.cpp
index 90159adf..91bfca50 100644
--- a/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.cpp
+++ b/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.cpp
@@ -9,9 +9,21 @@
 #include "RenderbufferObject.h"
 #include <MG_Util/Metrics/TextureMetrics.h>
 
+#include <atomic>
+
 namespace MobileGL {
     namespace MG_State {
         namespace GLState {
+            namespace {
+                // Starts at 1 so a zero-initialized cache slot can never carry a live
+                // renderbuffer's id.
+                std::atomic<Uint64> g_nextRenderbufferLifetimeId{1};
+            }
+
+            Uint64 RenderbufferObject::AllocateLifetimeId() {
+                return g_nextRenderbufferLifetimeId.fetch_add(1, std::memory_order_relaxed);
+            }
+
             RenderbufferObject::RenderbufferObject(Uint externalIndex) : m_externalIndex(externalIndex) {}
 
             Uint RenderbufferObject::GetExternalIndex() const {
diff --git a/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.h b/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.h
index 11153772..1e1f304b 100644
--- a/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.h
+++ b/MobileGL/MG_State/GLState/RenderbufferState/RenderbufferObject.h
@@ -42,9 +42,20 @@ namespace MobileGL {
                 Int GetDepthSize() const;
                 Int GetStencilSize() const;
                 Int GetSamples() const;
+                // Globally-unique, never-reused id for THIS object's lifetime - same contract
+                // and same motivation as BufferObject::GetLifetimeId(),
+                // ProgramObject::GetLifetimeId() and VertexArrayObject::GetLifetimeId(). A
+                // backend that folds a renderbuffer's IDENTITY into a cache key must use this,
+                // never the GL name (LIFO-recycled by glGenRenderbuffers) and never the heap
+                // address (recycled by the allocator): both let a deleted-and-recreated
+                // renderbuffer answer to a dead one's cache entry.
+                Uint64 GetLifetimeId() const { return m_lifetimeId; }
 
             private:
+                static Uint64 AllocateLifetimeId();
+
                 Uint m_externalIndex = 0;
+                const Uint64 m_lifetimeId = AllocateLifetimeId();
                 TextureInternalFormat m_internalFormat = TextureInternalFormat::RGBA;
                 Int m_width = 0;
                 Int m_height = 0;
diff --git a/MobileGL/MG_Test/State/ObjectLifetimeIdTest.cpp b/MobileGL/MG_Test/State/ObjectLifetimeIdTest.cpp
index 3290be28..0f4a3f02 100644
--- a/MobileGL/MG_Test/State/ObjectLifetimeIdTest.cpp
+++ b/MobileGL/MG_Test/State/ObjectLifetimeIdTest.cpp
@@ -32,6 +32,7 @@
 #include "Includes.h"
 
 #include <MG_State/GLState/BufferState/BufferObject.h>
+#include <MG_State/GLState/RenderbufferState/RenderbufferObject.h>
 #include <MG_State/GLState/VertexArrayState/VertexArrayObject.h>
 
 using namespace MobileGL;
@@ -138,3 +139,20 @@ TEST(ObjectLifetimeIdTest, LiveVertexArrayObjectsHaveDistinctLifetimeIds) {
 TEST(ObjectLifetimeIdTest, LiveBufferObjectsHaveDistinctLifetimeIds) {
     ExpectDistinctIdsWhileBothAlive<MG_State::GLState::BufferObject>("BufferObject");
 }
+
+// The renderbuffer had no lifetime id at all until plan B §11 P0 gave it one: it is
+// the one FBO attachment source whose identity a backend twin registry can only have
+// keyed on the heap address or the GL name, both of which recycle.
+TEST(ObjectLifetimeIdTest, RenderbufferObjectAtARecycledAddressCarriesAFreshLifetimeId) {
+    using MG_State::GLState::RenderbufferObject;
+    const int reuseCount = ProbeLifetimeIdAcrossAddressReuse<RenderbufferObject>("RenderbufferObject");
+    if (reuseCount == 0) {
+        GTEST_SKIP() << "inconclusive, not proven: this allocator never handed the same address back across 64 "
+                        "construct/destroy rounds, so the recycled-address case was never exercised";
+    }
+    RecordProperty("address_reuses_observed", reuseCount);
+}
+
+TEST(ObjectLifetimeIdTest, LiveRenderbufferObjectsHaveDistinctLifetimeIds) {
+    ExpectDistinctIdsWhileBothAlive<MG_State::GLState::RenderbufferObject>("RenderbufferObject");
+}