MobileGL/docs/archive/notes/p5e/TASK-pa.md

TASK-pa — the program family leaves the frontend on the draw and dispatch paths

Read PACKAGE-PREAMBLE-P5E.md first. Your tree is ~/w7/p5e-pa, branch p5e/pa, base 7c6f6886. Your slug for the gate driver is pa.

Your package is the largest single item left in P5e: 68 of the 109 red entries in the strict lane, and the one that fires once per draw on the device. Until it lands, no draw can be unbarriered, so the client keeps waiting for the apply thread at every draw and the split arm runs at roughly two thirds of the monolith frame rate.

1 What is measured, so you do not have to re-derive it

Per-entry marker census at your base (~/w7/p5e-logs/strict-census/census2.tsv):

marker	entries
Fatal{UnmigratedPipeInput, "GetProgramForDraw@DrawArrays"}	61
Fatal{UnmigratedPipeInput, "GetProgramForDispatch@DispatchCompute"}	7

Those 68 are yours. The other markers belong to other packages or are allowlisted; do not touch them.

Device, same base, Redmi, Minecraft 26.3-rc-3, ~849 draws/frame, GPU pinned, 30 s window, interleaved so the thermal drift is visible in both arms:

arm	fps p50	client GL thread ms/frame	apply thread ms/frame
monolith	267.9 / 195.1	3.898 / 4.781	—
inproc	166.4 / 143.5	6.098 / 6.958	5.305 / 5.653

2 The finding that makes this package small: the wire already carries everything

MGPipeShaderCsoRecord (MobileGL/MG_Pipe/PipeApply.h:391) already holds

• SharedPtr<const MG_State::GLState::ProgramArchive> Archive — filled by package pg, once per link, under a transport only, null under monolith BY DESIGN (ruling ID-81). A ProgramArchive (MG_State/GLState/ProgramState/ProgramArtifactsCodec.h:100) holds LinkArtifacts Link, SpirvArtifacts Spirv and LinkedStages.
• the three post-link mutable tails BlockBindings, SamplerUnits, StorageOverrides, with Signature and BindingsSerial.

And a program-pipeline composite gets its own record — the archive comment says so explicitly: "a program-pipeline composite and its stage programs are three records over one link's artefacts".

Now the key identity: every frontend accessor the two remaining readers call is a pure function of LinkArtifacts. ProgramObject::Artifacts() (ProgramState/ProgramObject.h:1342) returns const LinkArtifacts&, and each of GetMaxUniformLocation (:161), GetUniformType (:303), GetActiveAttributeLocationMask (:662), GetAttribType (:712) and GetUniformSamplerOrImageUnitIndex (:857) is a thin wrapper over it.

So this package adds nothing to the wire, changes no record, and regenerates no catalogue. It redirects readers from program->Artifacts() to record->Archive->Link. If you find yourself designing a new wire row, stop and report instead — you have probably found something this brief missed, and the integrator wants to hear it before you build it.

3 The sites

All in MobileGL/MG_Backend/DirectGLES/DirectGLES.cpp unless said otherwise.

3.1 The two unconditional accessor calls — these ARE the marker

site	code	note
:6006 in PrepareForDraw	const auto& currentProgram = MGB_CTX->GetProgramForDraw();	no arm test at all
:6746 in BindCurrentTextures() (the no-argument overload)	BindCurrentTextures(TextureImpl::CaptureDrawTextureSyncKeys(), MGB_CTX->GetProgramForDraw());	same

Merely CALLING the accessor trips the check — MG_Backend/MGPipe/PipeInputs.h:659 runs MGP_INPUT_CHECK(MGPipeInputField::GetProgramForDraw) before returning. So arm-selecting the call is the last step, not the first: it is only legal once every consumer can be served without it.

PrepareForCompute's GetProgramForDispatch is the same shape; find it and treat it identically.

3.2 The consumers that still genuinely need the object

(a) ResolveAndBindUnitTextures (:6090, reached from BindCurrentTextures at :6719). Reads GetMaxUniformLocation, GetUniformSamplerOrImageUnitIndex, GetUniformType (see the lambda at :6175-6183). Note that the memo KEY above it is ALREADY handle-only — tx2 landed that under ruling ID-86 (:6644-6663: drawProgram, shaderCsoSerial, bindingsSerial, samplerViewsSerial, contextSerial). It is only the miss path that still reads the frontend. Also note :6668 computes programKey from currentProgram.get() unconditionally; on the handle arm that value is unused for entry selection (:6671-6678 takes the byHandle branch) but it is still a read of the pointer, so it has to go too.

(b) SyncCurrentVertexAttributeValues (:2243, called from :6070). Reads GetActiveAttributeLocationMask (:2293) and GetAttribType. The code already names this work and says it is yours: its comment at :2258-2268 reads "WHAT IS NOT RETIRED HERE, and it is S4/pg's not vi's: the two program reads below (GetActiveAttributeLocationMask, GetAttribType). They are frontend object rows of the PROGRAM family and stay until pg carries the attribute mask and types in the ShaderCso record." The archive carries them; you are the package that reads them from there.

(c) BindCurrentProgramWithResources (:6756) already takes handleArm at :6763 and selects at :6774, but still receives the object as a parameter. Check every use of that parameter under the handle arm and make it null-safe in the sense of §5, not merely unused.

Sites :7374 and :7446 are already behind if (ProgramHandleArm()) — pg did those. Read them: they are the model for the shape the integrator expects, including FindShaderCsoRecord and ResolveProgramTwin.

4 The design you are asked to land

A single arm-selected accessor for the current draw (or dispatch) program's link artefacts, e.g.

• const MG_State::GLState::LinkArtifacts* CurrentDrawLinkArtifacts() that, under ProgramHandleArm() (Managers.h:714, Transport != Monolith && ProgramSubsystemEnabled()), resolves MGPipeApplier().DrawProgram to its MGPipeShaderCsoRecord and returns &record->Archive->Link, and under the monolith arm returns &program->Artifacts().

Then both readers in §3.2 take that, and the two calls in §3.1 become arm-selected. Whether the helper returns a pointer, a small view struct, or is spelled as two overloads is yours to choose; argue it in your report. Requirements on whatever you choose:

1. The arm is decided by MG_Config::Transport, never inferred from a pointer being null. This is ruling ID-81 and the phase has already paid for breaking it once: fix1 (66621767) and rulings ID-107 / ID-109 / ID-110 exist because a seam read "a handle was noted" as "the record arm is selected". Those are different statements. Read CURRENT_STAGE_PROGRESS.md §2.5 before you write the arm selection.
2. A null archive on the handle arm is a named refusal, not a fall-back to the frontend. Copy the shape of RefuseNullFrontendTextureOffTheHandleArm (Managers.cpp, search for it) and of MGB_TEXTURE_RECORD_ARM_SELECTED(). Quietly reaching back into the frontend would hide a missing record behind a picture that still looks right, which is what the subsystem A/B exists to expose.
3. The pull build must not gain a call. Guard so the preprocessed text of the pull flavour is unchanged (the #else arms of the existing macros are the precedent). G1 is a gate.
4. The monolith arm keeps its bytes. The push-monolith build is what the phone ships; it keeps the frontend arms token for token.

5 What must still work

• Program pipelines / separate shader objects. GLContext::GetProgramForDraw (MG_State/GLState/Core.cpp:609) returns either the plainly bound program or a cached COMPOSITE flattened from the bound pipeline's stage programs. Confirm from the emitter that the composite is the thing set_draw_program names and that pg archives it, then prove it: the lane has ProgramPipelineScenario and ImageLoadStoreSsoScenario. If the composite turns out NOT to have a record, stop and report — that is a design gap, not something to paper over.
• Relink. create_shader_state is re-issued on the same handle at every link that moves GetLinkVersion, including a FAILED relink (LinkStatus distinguishes them). The archive is replaced with it. Make sure a draw after a relink reads the new archive, and that a draw on an unlinked program declines exactly as it does today.
• The dispatch twin, with AtomicCounterScenario and UnboundImageDescriptorScenario as its lane evidence (those are 7 of your entries).

6 Red-once (required, quoted verbatim in your report)

1. Revert your arm selection so the handle arm takes the frontend path: the strict lane must go red again with GetProgramForDraw@DrawArrays, and the entry count must return to 61.
2. Make the archive lookup return null on the handle arm: your named refusal must fire, quoted from the entry's own log (MOBILEGL_LOG_FILE_PATH, because MGLOG_F does not reach ctest's captured stdout — see strict_census2.sh for the working recipe).
3. Put both back and show green.

7 Gate before you report

build rc=0 · unit 2250/2250 · isplit 116/116 · gpu 1294/1294 (this step is new, ID-109: it is the monolith runtime arm, and it is how the phase catches an ID-81 violation) · gens all rc=0 · strict: report the FULL per-entry marker census using strict_census2.sh, not just the pass count. Your package succeeds when GetProgramForDraw@DrawArrays and GetProgramForDispatch@DispatchCompute are gone from that table and nothing new has appeared.

8 Report

~/w7/notes/p5e/reports/pa-v1.md. Include: the read-site inventory you actually found (if it differs from §3, say so — this brief was written from a reading, not from a full audit), the design and why, the composite/relink evidence, the three red-onces verbatim, the before/after marker census, the gate table, and anything you were asked to do that you did not do, with the reason.