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

Package fb — framebuffers, attachments, images, blit from records (P5e wave 2)

Read in this order, all of it: PACKAGE-PREAMBLE-P5E.md, INTEGRATOR-DECISIONS-P5E.md (ID-86, ID-94 are yours), BRIEF-P5E.md (§0, §1, §2 "fb", §5, §6 rulings 7, 15, 16), CONTRACT-P5E.md §5.4, your scout report scout-S3.md (all of it), and the framebuffer / image rows of kimi-audit.md (rows 68-90) — report per row: retired / left barriered / not found. Notes: //wsl.localhost/Arch/home/swung/w7/notes/p5e/.

Your slug is fb; your tree is ~/w7/p5e-fb (branch p5e/fb, based on the landed id head, built). You CALL tx2's SyncTextureToBackendByHandle / SyncMipmapsToBackendByHandle (declared by c0e with asserting bodies; tx2 writes them in parallel) — code against the declarations and say so in the report; the integrator resolves the order at landing.

What "done" means for this family

The FBO and RBO twins resolve from the record (st.BoundFramebuffer[t] → FramebufferRecords[handle]), never from the binding slot or the frontend object; the draw-FBO and read-FBO attachment lists are keyed by {record.Fbo, ContentHash} with surface handles instead of borrowed attachment SharedPtr slots — this is the one unconditional per-draw live read of your family, so it is the package's core; SyncAttachmentSurface takes an MGPSurface, not a frontend attachment; the named blit resolves both endpoints from the two records; images come from BoundShaderImages[] with Access DECODED (ruling 16 / ID-94: the client already encodes it, the server comment is stale) and the sweep gate reads applier serials (ruling 7 / ID-86: ShaderImagesSerial, TextureShutterSerial, ContextSerial, g_backendContextGeneration — keep the window/high-water union); MarkWritableImageBufferTexturesGpuWritten is deleted under a transport (one edit paired with sb's deletion of the backend GPU-write marks — coordinate in the reports).

Scope

DirectGLES.cpp: the doors, the list keys, SyncReadFramebufferTextureAttachments, the draw-FBO list, the image block (SyncImageTextureBinding(const MGPImageView&), ResolveShaderImageRecord deleted, the sweep gate), SyncCurrentFBO*, BindCurrentFBO / SyncAndBind* / ForceBindCurrentFBO, Clear's FBO lines, both blit arms, the detach walk + the new reverse index, SyncRenderbufferObjectToBackend by handle. Managers.cpp / Managers.h: the FBO/RBO twin bodies, the reverse index (texture → FBO slots) tx2 needs for detach. Tests: MG_Test/Pipe/FramebufferEmitTest.cpp (the server twin of the existing client case), MG_Test/Pipe/ImageEmitTest.cpp (the access constants pinned on BOTH sides), and a new default-framebuffer-resize re-emit case (your scout verified the resize does re-emit — pin it).

Rulings that bind you

• ID-94 / ruling 16: MGPImageView::Access IS encoded client-side; move the decode to MGPipeValueTypes.h (c0e landed the enum) and delete the stale server comment.
• ID-86 / ruling 7: the sweep gate is the four applier/backend serials, never a backend re-mint counter; keep the union of the record window with the image-unit high-water mark.
• Your scout's open question on SyncReadFramebufferTextureAttachments being ungated on the framebuffer subsystem bit: its retirement changes behaviour in BOTH arms of the object A/B — name the delta in the report and re-baseline that A/B rather than hiding it.
• The renderbuffer cross-check that runs a client-allocator HandleOf on the apply thread under split: fix it as part of this package and say whether it was a latent correctness bug.

Red-once (execute, revert, quote)

1. SyncAttachmentSurface takes the frontend attachment again → strict names Fatal{UnmigratedPipeInput, "GetFramebufferBindingSlot"} on SnormAttachmentScenario.
2. The draw-FBO list key back to the pointer compare → the id guard's Fatal{RoleViolation, "MGPipeSlots"} (id's hook forces "unbarriered").
3. Map the image Access 1↔2 → FormatlessImageBakeScenario / ImageLoadStoreSsoScenario red plus the unit case.
4. The named blit back on the frontend objects → CopyImageLayeredScenario, LayeredAttachmentShapeScenario.
5. Keep the per-point version memo as a second gate → CrossFrameBufferScenario / the P4a seam scenario must stay green WITHOUT it.

Gate

build, unit, isplit, gens; strict (record the markers that disappeared); one on the FBO, blit and image scenarios you touch; the seam greps your scout listed must come back silent. Say explicitly whether a blit is still barriered after your change (your scout argued it need not be — the contract's predicate decides, and ra owns the flip).