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swung0x48 aba329cc53 [Docs] (Disaggregated): P6's plan and contract draft; the working notes move from a local directory into the repository 
Two things land together: the plan and contract draft P6 needs before it starts, and the
working notes that until now existed on exactly one machine.

1. P6's plan and contract draft (neither started; not one line of code)

     docs/Disaggregated/P6-SPAWN-PLAN.md      the package plan
     docs/Disaggregated/P6-CONTRACT-DRAFT.md  the contract draft (moves to
                                              MG_Remote/CONTRACT-P6.md when c6 lands)

   The three findings that mattered, all written into the documents:

   a. P6 is SMALLER than its roadmap cell suggests. The transport primitives are already in
      the tree and already tested: SocketDoorbell including hangup detection and the two
      lost-wakeup fences (Doorbell.cpp:211-360, four cases in FdPassingTest), SCM_RIGHTS fd
      passing, ShmSegment::Adopt, and the SurfaceOp / WindowKind schema already defined in
      protocol.fbs. inproc uses a real second shm mapping rather than an alias, and
      SessionRings.h:22-28 says that was done so today is not the first time it runs. P6 is
      assembly plus a control plane plus a process, not "write a socket transport".

   b. The evidence for "P6 is only a transport swap" has EXPIRED. It was bought by P5c, whose
      audit found 59 direct memory accesses in a tree that already looked clean. P5e changed
      the tree again. So the first package, a6, is a read-only audit that writes no code, and
      every contract row that depends on it is marked PENDING a6 rather than decided in
      advance.

   c. P6 does not get a game running on the phone. ANativeWindow* is meaningless in the child,
      and protocol.fbs:186-196's own comment says Android transfers the window out of band -
      that band is P12. P6 lands pbuffer / surfaceless / offscreen, which is what HeadlessGL,
      the split-equivalent lane and trace replay need, and which is exactly what P6's own exit
      gate measures. A real window reaching the server is a named refusal. This gets its own
      section because "P6 is done" would otherwise read as "the game runs now".

   The contract adds rule G: a role may not name a process-local handle. It extends P5c's
   rule E (a role may not name the other role's memory) from memory to identity - EGLDisplay /
   EGLSurface / EGLContext / ANativeWindow* / fd number / pid / mapped address either cross as
   a token this contract defines or they do not cross, and a descriptor crosses only through
   SCM_RIGHTS, where the kernel renumbers it.

   What P5e left for P6 gets its own section. The latch semantics are already designed
   (ARCHITECTURE.md:504) and are copied unchanged. What is new is that after run-ahead the
   client no longer waits while the peer process can DIE: the client holds records that were
   published and will never be applied, and Android's freezer suspends the child without
   closing anything. So slow and dead must be distinguishable WITHOUT a timeout threshold.
   That is P6's only new design; everything else is carriage. It shares a predicate with E1's
   outstanding re-specification (ID-122), and the two should be designed together.

   Two gates carried over from P5e's lessons: G2 requires integration-spawn's test-name set to
   match integration-split's name for name, because a differing set means the lane is quietly
   running less; and the arm-proof gate requires every entry to record the child pid and
   transport=spawn in its OWN private log - ID-124 established that this kind of false green
   really happens, and a spawn lane that actually ran monolith would pass every other gate.
   S2's shape must be settled before it is written, and the document says why: E1 is the
   cautionary case.

2. The working notes move into the repository (docs/Disaggregated/notes/, 415 .md files)

   ROADMAP / CURRENT_STAGE_PROGRESS / MEASUREMENTS cite ruling numbers, audit line numbers and
   the provenance of gate figures from ~/w7/notes/, a directory that exists on one machine and
   is under no version control. A record cited hundreds of times that lives only locally is not
   a record, so it moves in whole, with its directory structure intact.

   Only .md moves. Scripts, run logs, census and gate result JSON, patches, APKs and nm dumps
   stay where they are: they are evidence DATA rather than documents - large, regenerated per
   run, and mostly carrying absolute paths and device serials that mean something only on the
   machine that produced them. The mapping and this split are written in
   docs/Disaggregated/notes/README.md.

   Two exceptions are recorded there too: P6's BRIEF has been promoted to a first-class
   document and keeps no copy under notes/, so the two cannot drift apart; and recovered/ holds
   material salvaged from failed workflow runs, which may duplicate the like-named phase
   directories and is kept because a few of those were the only complete version at the time.

   CI's citation lint takes docs/Disaggregated/*.md only (non-recursive), and notes/ is
   deliberately outside it: those notes' file:line citations were written against their own
   code heads, and resolving them against today's HEAD would fail wholesale - which is not an
   error, it is their correct state as a historical record. To check one, use the revision it
   declares (--rev).

3. Inconsistencies fixed in passing

   - README.md's status line still said P5e was in progress while the stage table already said
     closed.
   - CURRENT_STAGE_PROGRESS's next-step item 1 still listed the exit gate as pending, though
     (a) and (b) were run in the previous commit; rewritten to closed plus the one item that
     actually remains (E1).
   - ROADMAP's P6 row still had the pre-phase plan in three of its cells; it now carries the
     package order, the scope boundary and the two new gates.

Checked with check_doc_citations.py: 125 citations across docs/Disaggregated/*.md, 0 problems.
2026-09-18 23:31:39 -04:00

26 KiB
Raw Blame History

S7 - identity: the five twin registries and the allocator (head 2fde7034)

Paths under MobileGL/. DG = MG_Backend/DirectGLES/DirectGLES.cpp, MG = MG_Backend/DirectGLES/Managers.cpp, MH = Managers.h, ST = MG_Backend/DirectGLES/SlotTables.h, SA = MG_Impl/Pipe/SlotAllocator.{h,cpp}, PF = MG_Impl/Pipe/PipeFill.cpp. Kinds: id = GetLifetimeId() + MGPipeSlots().FindByLifetimeId (ST:436-449, through MGPipeRefuseAllocatorFromApplyThread SA.cpp:257-273); mint = GetOrCreate(const StatePtr&) -> MGPipeSlots().Acquire (ST:215-268), a WRITE into the client allocator; live = a dereference of the frontend object beyond its lifetime id; rec = a handle-keyed arm that already exists beside the site.

1. The exact live reads of the family (per kind: today's key, every apply-thread site, hit/miss)

The mechanism common to all five (MH:309-620 StateBackendObjectRegistry wrapping BackendSlotTable): Find(StateObject*) ST:411-414 = HandleOf (id) + FindByHandle; GetOrCreate(StatePtr) ST:215-268 = Acquire (mint) + RememberHandle + entry.stateRef = stateObj (a frontend SharedPtr OWNED BY THE SERVER TABLE, ST:162,260); the per-table memo m_memoLifetimeId/m_memoHandle (ST:649-650, mutable, written from the apply thread on every id); OnFrontendObjectDestroyed ST:465-485 = id + MGPipeSlots().Free (monolith / NoSession fixture only). Every id and mint on the apply thread is legal today only through MGPipeFrontendKeyedRegistryScope / MGPipeReverseAnnouncementScope (SA.cpp:263-264); the two depth counters SA.cpp:303,324.

kind / table (key today) apply-thread sites at 2fde7034 kind; when
Buffer g_backendBufferResources MG:2757, BackendSlotTable<..., Buffer> MH:886-888 - ALREADY handle-keyed; the only frontend probe is HandleOfBuffer MG:2925-2941 (scope :2938) callers: EnsureBufferResource(obj) MG:3444-3455; IsBufferDrawClean(frontend,res) MG:3159-3162 -> IsBufferDrawCleanByHandle(HandleOfBuffer(frontend),...); MarkBufferGpuWritten MG:2945-2951. Reached per draw from S1 (VAO ensure walk, IBO arm), S5 (UBO/SSBO/atomic/XFB points), image buffer textures id; memo HIT and miss (IsBufferDrawClean runs on the hit path)
VAO g_backendVertexArrayObjects MH:1423-1424, TwinRegistry<VertexArrayObject, BackendVertexArrayObject, VertexElementsCso>; key = VAO lifetime id -> VertexElementsCso slot ResolveVaoTwin DG:1602-1633 (scope :1609, Find :1617, GetOrCreate :1618) from PrepareForDraw :4772 EVERY draw; DrawArrays :6729-6731, MultiDrawArrays :6775-6777 (Find) id every draw; mint on first draw of a VAO
Texture g_backendTextureObjects MH:1818-1819, key = texture lifetime id -> Texture slot SyncTextureObjectToBackend DG:1723-1802 (scope :1734, Find :1736, GetOrCreate :1738, re-resolve :1781/:1790) called from the three sync-list rebuilds :2308,:2381,:2457 (memo MISS), SyncImageTextureBinding :2660 (every image unit), CopyImageSubData :8294-8295, GenerateMipmap :9575-9578, CopyTex endpoint :9735; ResolveShaderImageRecord :2588/:2634 HandleOf; ResolveAndBindUnitTextures :4926-4928 Find (memo miss); ScopedDetachedTextureFramebufferAttachments :8837-8839 Find; GetTexImage :11884-11886; mip shape :9161-9162, :9216-9217 HandleOf (transport arm!); CopyTex monolith else-arm :8512-8515. MG: :5882-5884 HandleOf (image-bindable re-arm), :7087-7089 HandleOf inside SyncMipmapsToBackend - on EVERY texture sync on the handle arm, :8481-8483 ResolvePushedBuiltinSampler, :8717-8719 ResolvePushedTextureParams, legacy attach :9256-9261 Find/GetOrCreate, :9630 (monolith-gated), verify arm :10382-10384 id on every texture sync (hit or miss of the unit memo); mint on first sync
Renderbuffer g_backendRenderbufferObjects MH:2819-2820, key = rb lifetime id SyncRenderbufferObjectToBackend DG:9688-9710 (scope :9695, Find/GetOrCreate :9698-9701) from CopyTex endpoint :9714 and attach; MG:9310-9318 legacy attach; MG:9709-9720 HandleOf cross-check - NOT monolith-gated, unlike the texture twin at :9628-9632; MG:13570-13574 HandleOf inside BackendRenderbufferObject::SyncToBackend (every rb sync); verify arm :10403-10406 id per sync; mint on first attach
Framebuffer g_backendFramebufferObjects MH:1943-1944, key = FBO lifetime id; default FBO = kMGPipeDefaultFramebuffer{0,1} (MGPipeHandles.h:73), never a twin record arm SyncCurrentFBOByRecord DG:3197 GetOrCreateByHandle (rec) but :3228 NoteStateForHandle(record.Fbo, currentFBO) writes a frontend SharedPtr into the table; decline arm :3303/:3358/:3367-3369 Find/GetOrCreate; :3032 HandleOf (monolith-gated :3031); BindCurrentFBO decline :4585/:4592/:4602; SyncAndBindFramebufferObject :4646-4647; SyncAndBindFramebufferByHandle :4687 (rec) + :4700 StateForHandle (live: the note); named blit :8361 StateForHandle; ForEachLive :8904 (locks every stateRef); MG:9862,:10101 HandleOf monolith else-arms (m_pushedSyncHandle MH:1857 under transport) rec on the steady draw; the note is a live frontend read on every named blit / by-handle bind
Program / ShaderCso g_backendProgramObjects MH:2540-2541, key = program lifetime id -> ShaderCso slot (composites: the band, ProgramEmit.h:411-422) SyncCurrentProgram DG:4320-4432 (scope :4329, Find/GetOrCreate :4415-4416) EVERY draw; ResolveGlobalConstantsRecord :4236/:4242 HandleOf every draw with UBO bytes; BindCurrentProgramWithResources :5328/:5337 Find when the raw-pointer stash g_currentDrawFrontendProgram (:4097,:4509,:5333) misses; GetCurrentBackendProgram :5689-5691 Find (per sub-draw via :5716-5827); GetProgramBackendId :6166-6170 Find/GetOrCreate; SetStorageBlockBinding :10029-10031; MG:12949-12954 HandleOf inside BackendProgramObjectImpl::SyncToBackend id every draw; mint on first use
Sampler g_backendSamplerObjects MH:2678-2679, TwinRegistry<SamplerObject, BackendSamplerObject, SamplerCso> - TWO disjoint families in one table (MH:2681-2700): identity twins minted off the SamplerObject's lifetime id, and CSO twins at content-addressed handles (SamplerEmit.h:427 Allocate with no lifetime id) identity family: ResolveUnitSamplerBackend DG:4989-5013 (scope :4993, HandleOf :4999, g_unitSamplerLookupMemos), the sampler-pass decline arm :5623-5630 GetOrCreate(samplerObject) = a MINT from the apply thread on every unit the record arm does not cover, MG:13264-13280 HandleOf inside BackendSamplerObject::SyncToBackend(object). CSO family: ResolveSamplerCsoTwin MG:13460-13486 GetOrCreateByHandle(cso) from BindCurrentUnitSamplers :5146 and the program pass :5616 rec (CSO); id + mint (identity)
SamplerView g_backendSamplerViews MH:2761-2764 handle-only BackendSlotTable; key = texture lifetime id -> SamplerViewCso slot no backend caller of HandleOfSamplerViewForTexture (MG:4535-4546, scope :4544); its only caller is the harness MG_IntegrationTest/Harness/PipeApplyPeek.cpp:165 none on the draw path

Outside DirectGLES: MG_Impl/Pipe/ResourceTracker.h:723 (MGPipeAnnounceBufferGpuWritten, Magma), VulkanRenderer.cpp:4554, :4634, :8986 (Magma hidden resources' destructors + MGPipeSlots().IsLive in the blit endpoint resolve). Scope-site census: 20 in DG (:1609 :1734 :2588 :3303 :4236 :4329 :4585 :4926 :4993 :5328 :5689 :6166 :6729 :6775 :8837 :9161 :9216 :9695 :10029 :11884), 15 in MG (:256 :2938 :4544 :5882 :7087 :8481 :8717 :9256 :9310 :9709 :10382 :10403 :12949 :13273 :13570), 1 in ResourceTracker.h, 3 in Magma, 3 in MG_Test/Wire/RemoteClientTest.cpp:1883-1903.

Corrections to the E note. (i) The VAO twin key is NOT content-addressed: VertexInputEmit.h:170-172 mints the VertexElementsCso slot with Acquire(VertexElementsCso, vao->GetLifetimeId()), one CSO per VAO, re-created on the SAME handle when ConfigVersion moves (:178-179), so the twin key already equals MGPipeApplier().BoundVertexElements. (ii) The same holds for every kind: Texture TextureEmit.h:422 / PF:1495, Renderbuffer PF:1499, Framebuffer FramebufferEmit.h:257 / PF:1503, ShaderCso ProgramEmit.h:411-422 / PF:1507, SamplerView SamplerEmit.h:886-887 all mint off the object's own lifetime id, so HandleOf(obj) on the server always answers the handle the records carry. The rekey is therefore a REPLACEMENT OF THE LOOKUP ARGUMENT, not a re-keying of the table.

2. What the records and applier state already carry

  • Handle-indexed record tables, Gen-checked on every read (MG_Pipe/PipeApply.h:486-524; readers MG:4325-4360 PipeTextureRecordForHandle / PipeRenderbufferRecordForHandle / PipeSamplerCsoRecordForHandle / PipeSamplerViewRecordForHandle / PipeShaderCsoRecordForHandle (band-aware), PushedFramebufferRecord MH:1963, FindShaderCsoRecord DG:4243; PipeApply.cpp:444,481,488,505 !Live || Gen != handle.Gen -> nullptr).
  • The bound handles: BoundVertexElements :594, BoundFramebuffer[2] :646, BoundSamplerViews[u].Texture :673, BoundSamplerStates[u], BoundShaderImages[u].Res, DrawProgram/DispatchProgram/BoundShaderCso :691-693, VertexBuffers[].Res, IndexBuffer.Res; the verb workspace VerbBlitReadFbo/DrawFbo, VerbCopyTexDst, VerbMipRes, VerbIndirect* :733-755; MGPSurface.Res in FramebufferRecords.
  • Twin creation by handle already exists per kind: GetOrCreate(handle) ST:294-342 (forward Gen = recycle & reset :338, backward Gen = refused :331), GetOrCreateByHandle MH:407-414, AdoptTwinByHandle MG:4148-4152, GetOrCreateBufferResourceForHandle MG:2887-2908, GetOrCreateSamplerViewForHandle MG:4505-4528, ResolveSamplerCsoTwin MG:13474, SyncAndBindFramebufferByHandle DG:4677-4712, CopyTex split arm DG:8487.
  • Twin death by handle already exists for all seven kinds: object_death (opcode 78, MGPHandleOnly MGPipeTypes.h:93-98, PipeCalls.def:265, kCtxObject) emitted by EmitObjectDeathRecord MG_Remote/Client/WireTables.cpp:569-608 (GL thread, the client's own allocator) -> ServerVerbSink::OnObjectDeath PipeApplier.cpp:988-1013 -> ReleaseTwinsForWireObjectDeath MG:328-372 -> ReleaseTwinByHandle ST:498-507; Buffer via resource_destroy -> Ops_H_Destroy MG:2424-2444 ReleaseByHandle. Order on the client is fixed (PF:1623-1626 NotifyAndFree: notice -> record out -> Free), so the death record precedes the slot's next handout on the ring. Under BatchWaits=1 (default, Config.h:493) object_death, every create_*/delete_* (kCtxCso) and every set_* (kCtxState) already publish WITHOUT waiting (ClientSession.cpp:915-920); EmitAndWait at WireTables.cpp:604 is a name only.
  • Client-side lifetime-id -> handle maps that STAY client: MGPipeSlotAllocator::ByLifetimeId SA.h:146, MGPipeResourceTracker::m_bySlot ResourceTracker.h:535 (slot -> BufferObject* inverse for writebacks), the emitters' latches (VertexInputEmit.h:174, SamplerEmit.h:889, TextureEmit.h:455-470 ResolveTexture), EmitTables.cpp:1076-1082 PublishedTextureHandle. All GL-thread; none is touched by this design.

3. The gap (what does not exist yet)

No new wire record and no new field is needed for identity. The gaps are server-side shapes:

  1. Per-kind by-handle resolvers on the draw path are missing for VAO, Program and Texture-at-draw: ResolveVaoTwin(handle), ResolveProgramTwin(handle), ResolveTextureTwin(handle) (the shape of ResolveSamplerCsoTwin). AdoptTwinByHandle is the body; the release-build voice of the refusal is per kind (MG:2893-2898's shape).
  2. The twin sync bodies take the frontend object (MG:4881 VAO, :7049 mips, :8802 params, :10044 FBO, :11922 program, :13184/:13188 sampler, :13550 rb) and resolve their own record through HandleOf(obj) (MG:7089, :12954, :13574). Identity's requirement on S1-S5: every body becomes SyncToBackend(MGPipeHandle, const <Record>&) and stores m_handle (the m_pushedSyncHandle pattern, MH:1857) - the object parameter is deleted, not defaulted to null.
  3. The state note (NoteStateForHandle writer DG:3228; readers :4700, :8361) and ForEachLive's stateRef walk (DG:8904, the one direct iteration) are frontend SharedPtrs in server memory. S3 owns the replacement: the by-handle FBO sync reads FramebufferRecords[h].State only; ScopedDetachedTextureFramebufferAttachments walks FramebufferRecords for surfaces naming texture handle T (an O(records) walk, or a reverse index texture -> FBO slots maintained at set_framebuffer_state).
  4. Raw-pointer memos: g_currentDrawFrontendProgram (DG:4097) -> a handle stash; g_unitSamplerLookupMemos (DG:4985) and the sampler identity family (:4989-5013, :5623-5630, MG:13264-13280) are DELETED - a unit whose BoundSamplerStates[u] is null while the frontend holds a sampler is a missing bind_sampler_states, which under run-ahead is Fatal{UnmigratedPipeInput,"SamplerObject@draw"} (strict), never a mint (S2 to ratify).
  5. BackendSlotTable has no composite band. EntryAt(handle.Slot) ST:581-584 resizes to the slot; a program-pipeline composite (slot >= 983040, SA.cpp:457, kMaxHandleSlot = 1<<20 ST:154) grows g_backendProgramObjects to ~983k entries (~40 B each). Today reachable through GetOrCreate(StatePtr) for a composite program; after the rekey it is the ordinary path. The table gets a m_band vector indexed by slot - base, as the allocator (SA.h:144) and the applier (PipeApply.h:511) already do.
  6. MG:9709-9720 (renderbuffer attach cross-check) lacks the Transport == Monolith gate its texture sibling has (MG:9628-9632): a live id probe under transport today. Fixed by the rekey (the check is deleted; AdoptTwinByHandle is the whole identity test) - noted so its disappearance is not mistaken for a lost check.
  7. The client-side rule that lets the server never miss: the record naming a handle is ON THE RING BEFORE the verb that reads it. Already true - create_* from the validate point / birth hooks (PipeMutation.h:996-1184), set_* from the tracker walk, object_death from the destructor - and the applier's Gen check turns any violation into the loud refusal (PipeApply.cpp:1740-1750), not a wrong twin.

4. The retirement design (server shape after P5e)

ST (BackendSlotTable), handle-only under MOBILEGL_PIPE_PUSH: delete GetOrCreate(const StatePtr&), HandleOf, Find(StateObject*), OnFrontendObjectDestroyed, NoteStateForHandle/StateForHandle, Entry::stateRef, the memo pair and RememberHandle/ForgetHandle; keep GetOrCreate(handle), FindByHandle, ReleaseByHandle, ReleaseTwinByHandle, LiveGenAt, the holder list, ForEachLive re-typed as fn(MGPipeHandle, const BackendPtr&); add the composite band. Entry becomes {backend, Gen, Live}. The StateObject template parameter survives only as a name. The pull build never compiles this header (ST:14-16, :86), so G1 holds by construction.

MH (StateBackendObjectRegistry): the slot arm forwards only the handle members; the legacy UnorderedMap<StateObject*> arm stays exactly as it is under MOBILEGL_PIPE_LEGACY_MEMOS (the A/B of ARCHITECTURE 9.6; CMakeLists.txt:43 default ON). DestroyByLifetimeId becomes legacy-arm-only; the notice consumer OnFrontendStateObjectDestroyed MG:206-320 keeps the split arm (EmitObjectDeathRecord), keeps the monolith switch for the LEGACY arm, and the slot arm's monolith death is the same object_death route applied synchronously (MGPipeRouteObjectDeath under Transport=monolith = direct apply) - one death path per arm, the scope at MG:256 deleted. The NoSession fixture hop (MG:224-246) is deleted: a server-role fixture with no client session gets no deaths (its twins die with the backend at Stop, which is what happens today past Running()==false anyway).

Twin key = the record's handle, resolved from applier state, never from an object:

  • VAO: ResolveVaoTwin(st.BoundVertexElements) in PrepareForDraw; DrawArrays/MultiDrawArrays client-side attribute paths are refused under split already (S1 confirms) - their Find becomes the monolith legacy arm only.
  • Program: SyncCurrentProgram(st.DrawProgram), PrepareForCompute(st.DispatchProgram), ResolveGlobalConstantsRecord(handle); g_currentDrawBackendProgram keyed by {slot,gen}; GetProgramBackendId(name) / SetStorageBlockBinding(name) are monolith sticky entries (DG:6152, :10022) - under split they are unreachable (P5b class-C refused or carried as MGPSetStorageBlockBinding.ShaderCso, EmitTables.cpp:1267).
  • Texture: SyncTextureTwin(handle) called with BoundSamplerViews[u].Texture, BoundShaderImages[u].Res, FramebufferRecords[h].State.Color[i].Res, VerbCopyTexDst, VerbMipRes, MGPCopyImage src/dst; SyncMipmapsToBackend reads the staged store by handle (tx already does, CONTRACT-P5C.md §2.2).
  • Renderbuffer: AdoptTwinByHandle(surface.Res) (already, MG:9719) + by-handle SyncToBackend(handle, record).
  • Framebuffer: GetOrCreateByHandle(BoundFramebuffer[t]) / record.Fbo (already); the decline arms (DG:3303-3370, :4568-4602) become monolith-legacy-only; g_fboRecordsTrusted=false under a transport is Fatal{ProtocolCorruption}.
  • Sampler: the CSO family only (ResolveSamplerCsoTwin(st.BoundSamplerStates[u])); the table is renamed to what it is.
  • Buffer: EnsureBufferResourceForHandle(nullptr, h) / IsBufferDrawCleanByHandle(h, res, nullptr) from every consumer that holds h (S1/S5 name them); HandleOfBuffer and MarkBufferGpuWritten(obj) become monolith-only, and the split GPU-written announcement takes the handle (MarkBufferGpuWrittenByHandle).

"Is it clean / does it need re-sync" from server-owned serials: each twin stores m_handle and the record serial(s) it last consumed (m_syncedResourceSerial, m_syncedParamsSerial, m_syncedShaderCsoSerial, m_syncedRecordHashes already exist: MH:1400-1410, :1800-1812, :2750, :2820). FindByHandle answering null or a different Gen = a different object = full sync; equal handle + equal serials = clean. No frontend version is read anywhere. (S1-S5 own the per-kind serial sets; the identity invariant is only: the compare is {handle, serial}, never {pointer, version}.)

Twin creation moment: the first apply that resolves the handle through GetOrCreate(handle) - a verb, a bind, an attach - AFTER the record naming it was applied (the applier refuses a bind/verb naming an unknown or stale handle, PipeApply.cpp:2266, :2549, :2625, :2683, :2896). Creation is lazy, exactly as today; no twin is minted at create_*. Twin death moment: the apply of object_death / delete_* / resource_destroy (in ring order, after every verb that named the generation), or the server backend's own destruction at Stop (MG:188-212 InProcessTeardown). applier_reset does not touch twins or object records (PipeApply.h:800-832); MGPipeApplierReleaseObjectRecords :841 is wired to nothing outside tests and stays so.

The ABA answer ("recycled slot, new gen"): Gen moves only on reuse (SA.cpp:410-419); the client frees a slot only after its death record went out (PF:1623-1626); the ring is in order; so at the server every record naming {s,g} is applied before object_death{s,g}, which is applied before create{s,g+1}. Even with the death skipped (an object that never crossed emits none, WireTables.cpp:595-596), GetOrCreate({s,g+1}) finds Live && Gen != g+1 and resets (ST:338); FindByHandle({s,g}) after the recycle answers null (:424); a backward {s,g-1} is refused (:331). No wait is involved and none is added: run-ahead changes nothing here. What the client must NOT do is hold a server-side SharedPtr to a frontend object - after P5e the server holds none (no stateRef, no state note, no object rows in gPipeInputs under run-ahead), so the P5d deferred-destroy queue (PipeMutation.h:957-975, PF:999-1046) loses its producer; it stays as a guard that logs once if it ever enqueues under run-ahead.

The two scopes: MGPipeFrontendKeyedRegistryScope is deleted (class, 35 Espryt sites, the SA.cpp:264 exemption, the ResourceTracker.h:723 site with it once S5 carries the handle). MGPipeRefuseAllocatorFromApplyThread becomes Transport != Monolith && OnApplyThread -> Fatal, unconditional for DirectGLES. MGPipeReverseAnnouncementScope is the Magma question (part 7).

5. Monolith / G1

  • Pull build: untouched - every symbol above is under MOBILEGL_PIPE_PUSH or MOBILEGL_BUILD_DISAGGREGATED; the TwinRegistry alias keeps the two-argument mangled name (MH:626-634); G2/G14 unchanged.
  • Push build under Transport=monolith: the applier is in-process and populated synchronously by the same records (MGPipeRoute* == MGPipeApply* under monolith), so the handle bodies run under monolith too and read MGPipeApplier() state that is current at the verb. Behaviour identical; bytes differ. The selection is the FAMILY BIT (XSubsystemEnabled(), the 0x1fff mask), not a transport check: bit clear -> the legacy UnorderedMap arm (its HandleOf on the GL thread is legal), bit set -> handle arm. Under a transport the bits are caps-required, so only the handle arm is reachable and a legacy-arm entry from the apply thread is the Fatal. The monolith entry points that reach the backend WITHOUT a record - GetProgramBackendId(name), GetTexImage, CopyImageSubData, the sticky forwards - keep their object-taking monolith bodies and resolve the handle on the GL thread through the emitter-side maps (PublishedTextureHandle's shape), i.e. the resolution moves to the SAME side the mint lives on.
  • If the integrator rules "monolith bytes identical" instead, the alternative is #if MOBILEGL_BUILD_DISAGGREGATED + Transport != Monolith around each handle body with the frontend body kept beside it; it keeps 35 sites alive and the scope classes with them, and is not recommended.

6. Red-once

  1. Revert ResolveVaoTwin's handle arm (put Find(vao.get()) back) with the scope gone: the first draw under integration-split aborts Fatal{RoleViolation, "MGPipeSlots"} naming HandleOf (SA.cpp:265-272); the same for SyncCurrentProgram and SyncTextureTwin.
  2. RemoteGuards.AnAllocatorProbeInsideAnExemptionScopeOnTheApplyThreadIsAllowed (RemoteClientTest.cpp:1881-1895) is deleted with the scope; a new ...FromTheApplyThreadIsFatalEvenAtTheOldDebtSites posts HandleOf through RunOnApplyThread and expects the abort. :1866-1879 and :1901-1913 stay as the control.
  3. ABA under run-ahead: CtWireScenario.TextureDeathCrossesAndTheRecycledSlotAnswersTheNewObject / FramebufferDeath... (CtWireScenario.cpp:120-215) and HandleRecycleScenario's aba arm (:140-149) run with the draw wait removed; skipping the ReleaseTwinByHandle in OnObjectDeath must render the dead twin's colour (red).
  4. Unit: DirectGLESSlotTable.AGenerationBehindTheLiveTwinIsRefusedRatherThanAdopted (SanityTest.cpp:4898) kept; a new ACompositeHandleDoesNotGrowTheOrdinaryTable pins the band; the cases that drive GetOrCreate(StatePtr) / the death notice (:3499-3960, :4061, :4241, :4378) are moved onto the legacy arm or rewritten by handle; ScopedDirectGLESTextureBindings (:230-262) keeps its by-value registry copy (holder list unchanged).
  5. Strict lane: integration-split-strict green for the migrated verbs is the gate that a frontend-keyed resolution cannot hide behind a memo hit (P5e-3).

7. Risks and what S7 could not settle

  • Magma. VulkanRenderer.cpp:4554, :4634, :8986 and ResourceTracker.h:723 are apply-thread allocator touches P7 retires; with the guard unconditional they abort on the first Magma frame under inproc. Ruling needed: keep ONE scope, renamed and compiled for DirectVulkan only (MagmaP7AllocatorDebtScope), with the guard's exemption keyed on the backend kind; Espryt has no exemption. (P5e-4 keeps Magma lockstep either way.)
  • Sampler identity family deletion changes what a draw does for a unit the record arm does not cover (DG:5601-5630): today it mints a twin off the object; after P5e it is a Fatal under strict. S2 must confirm bind_sampler_states covers [0, maxTouchedUnit] (E's caveat A8) before the arm is removed.
  • ForEachLive / the detach walk (DG:8893-8935) needs S3's reverse index; without it the by-handle FBO table cannot answer "which twins attach T" and the walk silently does nothing (the handle-keyed entries are already invisible to ForEachLive, ST:282-285).
  • NoSession server-only fixtures (MG:224-246, CONTRACT-P5C.md §5.2 amendment) lose their death delivery; the affected fixtures are ServerLoop unit cases with no client - to be enumerated by the integrator (grep RunOnApplyThread users in MG_Test/Wire).
  • Composite band in the twin table (part 3.5) is a pre-existing ~40 MB growth on any program pipeline; it becomes the ordinary path after the rekey, so it is a P5e prerequisite, not a follow-up.
  • Ordering of packages. Every other family's design calls a by-handle resolver; the ST/MH rekey + the per-kind resolvers + the band land FIRST (one worktree, no behaviour change under lockstep), then S1-S5 swap their arguments, then S6 removes the wait. The guard flip (delete the scope) is the LAST commit of the identity package, because it is the red-once for every site that was missed.
  • Not verified: whether any MGPipeApplier() bound handle can be null at a verb that today resolved a non-null frontend object (a family bit clear under transport). The caps-required-bits rule (P5e-4) is what makes that unreachable; S6 to pin.
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