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

Package id — identity: handle-keyed twins, the guard, the scopes (P5e; lands second)

Read in this order, all of it: PACKAGE-PREAMBLE-P5E.md, INTEGRATOR-DECISIONS-P5E.md (ID-90 and ID-96 are yours), BRIEF-P5E.md (§0, §1, §2 "id", §6 rulings 1, 4, 12, 13), CONTRACT-P5E-draft.md §4 (all of it) and §9, your scout report scout-S7.md (all of it), and the rows of kimi-audit.md lists (a) and (b) (the scope construction sites and the frontend pointers held across records). All in //wsl.localhost/Arch/home/swung/w7/notes/p5e/. Your slug is id; your tree is ~/w7/p5e-id (built, on branch p5e/id at 2fde7034).

Package c0e is being implemented IN PARALLEL on p5e/c0e by another agent; it declares MGPipeApplierCurrentRecordIsBarriered() and MGPipeBarriered(...) in MG_Pipe/PipeApply.h. You do not wait for it: declare exactly those two names yourself in the same header with the contract's signatures (a minimal body: barriered = true for every record until ra lands - lockstep is unchanged by your package), and note in the report that c0e owns the final declaration; the integrator resolves the textual overlap at landing (one hunk).

Deliverables (lockstep behaviour unchanged; the registries stop being frontend-keyed on the server)

1. MG_Backend/DirectGLES/SlotTables.h: the composite band m_band; ForEachLive re-typed as fn(MGPipeHandle, const BackendPtr&); the frontend-keyed members (HandleOf(stateObj), Find(StateObject*), GetOrCreate(const StatePtr&), stateRef, NoteStateForHandle, the mutable memo) kept ONLY as monolith glue, each asserting !MGPipeApplierIsUnbarrieredApply() in split builds (a named Fatal, not a silent path).
2. Managers.h:309-640 and the resolvers: ResolveVaoTwin(MGPipeHandle), ResolveProgramTwin(MGPipeHandle), ResolveTextureTwin(MGPipeHandle) in the shape of SamplerImpl::ResolveSamplerCsoTwin (Managers.cpp:13457-13486 at base): handle in, record first, GetOrCreate(handle), no frontend touch, no allocator probe; AdoptTwinByHandle as the shared body. The family packages will call these; if c0e's seam declarations differ in spelling, yours win for these three (tell the report).
3. Managers.cpp:188-372: teardown; OnFrontendStateObjectDestroyed — delete the NoSession mailbox hop (:224-246) and the scope at :256; ReleaseTwinsForWireObjectDeath by handle; the twin death moment per CONTRACT-P5E §4.2, the ABA answer §4.3 (a recycled slot with a new gen re-mints; an old-gen handle is refused by FindByHandle's gen compare — pin it).
4. MG_Impl/Pipe/SlotAllocator.{h,cpp}: the guard MGPipeRefuseAllocatorFromApplyThread exempts only "inside a scope AND the current record is barriered" (contract §4.4); MGPipeFrontendKeyedRegistryScope stays as a class (the family packages delete their 20 sites); MGPipeReverseAnnouncementScope → MagmaP7AllocatorDebtScope, backend-kind-keyed (ruling 12), with the four Magma sites renamed (VulkanRenderer.cpp:4554, 4634, 8986, ResourceTracker.h:723 at base — re-resolve) and Espryt's HandleOfBuffer site (Managers.cpp:2933 at base) kept under the old scope name until vi/sb retire it (say so in the report). P5d round 3 already made the scope counters plain (apply-thread-only writers) — keep that shape.
5. MG_Remote/Server/PipeApplier.cpp ApplyOne: set CurrentRecordBarriered from MGPipeBarriered (one line; ra rebases on it).
6. Tests: MG_Test/SanityTest.cpp cases the brief lists (moved to the legacy arm or rewritten by handle; new ACompositeHandleDoesNotGrowTheOrdinaryTable); MG_Test/Wire/RemoteClientTest.cpp (...IsAllowed deleted; new ...FromTheApplyThreadIsFatalEvenAtTheOldDebtSites posting HandleOf through RunOnApplyThread with the barriered flag forced false by a test hook). ID-96: enumerate every NoSession server-only fixture that loses death delivery when the hop is deleted (grep RunOnApplyThread MG_Test/Wire), rewrite them to drive object_death by handle through the applier, delete only what cannot be expressed that way, and list each in the report.

Red-once (execute, revert, record)

With the test hook forcing "unbarriered", HandleOf from the apply thread → Fatal{RoleViolation, "MGPipeSlots"}; put the exemption back → the case is green → red by expectation. Skip the Gen reset in the ABA case → red.

Gate

build, unit, isplit, gens, strict — unit and isplit must be exactly base-green (2203 / 111 at base; new names only add). G2/G14: skip twins for split-only cases. Commit in slices (tables; resolvers; death path; guard + scopes; tests). Report per the preamble.