docs: add deleted-machinery grep sweep to the collision handoff bundle

Late-arriving adversarial-review artifact: deletions confirmed clean
(no surviving consumers, no post-Revoke dereference), one dead orphan
(CollisionWorldStateSlot.TransferTo), two stale test names, and the
stale-docs catalog for whoever lands the collision work.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/research/2026-08-02-collision-throughput-handoff/grep-sweep-deleted-machinery.md

@@ -0,0 +1,68 @@
+# Grep sweep — deleted collision machinery (2026-08-02, against the WIP O1-O3 tree)
+
+Produced by an adversarial-review subagent (completed after the review
+round was halted). Verdict summary: the deletions are CLEAN — no
+surviving consumer of the journal/peer-rebase/draft-retirement/staging-
+clone machinery, and no post-`Revoke()` dereference path found. Two
+actionable leftovers and a stale-docs catalog for whoever lands the
+collision work.
+
+## Actionable
+
+1. `CollisionWorldStateSlot.TransferTo` (`CollisionWorldState.cs:270-281`)
+   is fully DEAD — zero callers incl. tests. Delete it (comments at
+   `PhysicsEngine.cs:311/:379` reference it historically and are
+   accurate).
+2. Two test names are stale terminology with live bodies:
+   `RuntimePhysicsStateTests.cs:1730`
+   (`PostCommitOwnerMutationWinsOverQueuedPeerRebase`) and `:2264`
+   (`PendingOrActivePeerRebaseCannotResurrectRetiredLandblock`) — rename
+   when touched.
+
+## Confirmed DEAD (zero refs in src/tests/tools/docs)
+
+- `LandblockRetirementCursor`/`Step`/`CreateLandblockRetirementCursor`
+- `CollisionStagingBuilder.Advance/.WorkUnits/.Completed/.SuppressLandblock`
+- `CopyOneOutsideTarget`
+- Owner journal: `_collisionOwnerJournal`, `EnqueueCommittedRebase`,
+  write-through, draft retirement
+
+## Confirmed LIVE (name overlap, different concept — do not "clean up")
+
+- `InstallLandblockClone` (`PhysicsEngine.cs:576,673`) — the per-landblock
+  delta-apply installer, not the old clone loop.
+- `MirrorOwnerFrom` (`ShadowObjectRegistry.cs:1961,2011,2079`) —
+  repurposed for the O3 commit-time reflood.
+- `OwnerMutated`/`OwnerPrefixMembershipChanged` events — general-purpose,
+  unrelated to the deleted journal.
+- `RetryDeferred` (`RuntimeSetPositionState.cs:4103` et al.) — the
+  deferred-SetPosition subsystem, unrelated.
+- `LandblockReplacementBuilder` `.WorkUnits/.Advance/.Completed` — the
+  live seal builder, not the deleted staging builder.
+
+## Post-Revoke audit
+
+`Revoke()` has exactly one call site (`PhysicsEngine.cs:381`, end of
+`CommitLandblockReplacement`). `MarkCommitted` (`RuntimePhysicsState.cs:
+372-380`) + `LandblockPhysicsPublisher.cs:505/:1177-1183` guards mean no
+production or test site dereferences a revoked slot. `prepared.Engine`/
+`DataCache` remain unguarded by design (ObjectDisposedException is the
+intended revoked behavior).
+
+## Stale docs/comments that now describe the DELETED design (rewrite when
+landing the collision work)
+
+- `docs/architecture/acdream-architecture.md:504-566` — full section on
+  journal/write-through/rebase/root-transfer: STALE, needs rewrite to
+  the per-landblock delta commit.
+- `memory/project_collision_port.md:50-88` — same content class, STALE.
+- `docs/research/2026-07-31-atomic-collision-generation.md` — whole file
+  documents the deleted mechanism with no supersession note (the
+  prepared banner is in docs-drafts.md).
+- `src/AcDream.Core/Physics/PhysicsDataCache.cs:126-130` XML doc —
+  describes the deleted one-leaf-per-step materialization.
+- `src/AcDream.App/Streaming/LandblockPhysicsPublisher.cs:621-625`
+  comment — "zero-work root transfer" no longer true.
+- Correctly archival (no action): `retail-divergence-register.md:113`
+  (~~AD-6~~ retired entry); the placement-cutover plan + C3c closeout
+  (they name the clone as the known problem being fixed).