wip(physics): collision O(changed) delta-commit (O1-O3) - ON HOLD, feel-test failed

Publication-throughput rework per the D2 design (docs/research/
2026-08-02-collision-throughput-handoff/design-note.md): O1 per-prefix
installed-key ledgers replacing the seal's full-map scans; O2 per-
landblock delta commit (LandblockReplacementApplyCursor against the
active root) replacing whole-world TransferTo; O3 empty staging root,
commit-time reflood (CObjCell::init_objects 0x0052B420 ->
recalc_cross_cells 0x00515A30), journal/peer-rebase machinery deleted
(~1,900 lines net).

Automated gates green: Runtime 999, Core physics 2,135, App 4,039/3,
Headless 79, complete solution 10,812/0/4; lifecycle gate PASS
(connected-world-gate-20260802-193029). Soak 194423: publication-side
acceptance fully met (37 -> 4 failures, all convergence dims zero,
loadedLandblocks baseline-identical, waitCue 6/9 -> 1/9).

COMMITTED AS WIP ON USER DIRECTION - NOT ACCEPTED. The user feel-test
FAILED on this tree: monsters still pop into existence at close range,
monsters spawned mid-air far ahead, static placements visibly wrong,
plus 243x "Landblock already has a full retirement receipt"
InvalidOperationException catch-retry loop during origin recenter
(launch-feeltest-oclone.log). The 4 remaining soak failures
(pendingLandblockRetirements 131/122 at the Caul->Sawato stops) and the
implementer's "exposed pre-existing" classification are under
re-judgment against that loop. Dual reviews were dispatched and then
stopped mid-flight on user direction; NO review has passed this commit.
Full problem inventory + next-agent instructions:
docs/research/2026-08-02-collision-throughput-handoff/.

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

docs/research/2026-08-02-collision-throughput-handoff/docs-drafts.md

@@ -0,0 +1,109 @@
+# Docs-commit drafts — collision publication-throughput fix (O1/O2/O3)
+
+Drafted per contract; NOT applied to the repo. Apply in the docs commit after
+code review. Register judgment executed as pinned: AD-6 stays retired with a
+successor note; the residual timing/order compression gets a NEW row (AD-62).
+
+---
+
+## 1. `docs/architecture/retail-divergence-register.md`
+
+### 1a. Append to the retired ~~AD-6~~ row (line 113), at the end of column 2
+
+> **Successor note (2026-08-02, collision publication-throughput fix
+> O1/O2/O3):** the whole-world staging clone, the owner-mutation journal, the
+> peer-rebase/retirement cursors, and the zero-managed-byte whole-root
+> transfer this row describes were deleted. The shipped mechanism is now the
+> per-landblock delta commit this row's retail anchor always pointed at:
+> admission captures an O(1) empty target-only staging root
+> (`PhysicsEngine.CollisionStagingBuilder`), the seal enumerates one prefix's
+> installed keys through the `CollisionWorldState` per-prefix ledgers, and
+> `PhysicsEngine.CommitLandblockReplacement` drains the sealed delta into the
+> ACTIVE root in one synchronous update-thread call, recalculating every
+> associated owner's cross-cells against the live world
+> (`ShadowObjectRegistry.ApplyCommittedOwnerReplacement` +
+> `RefloodPrefixOwnersAfterReplacement`; retail `CObjCell::init_objects`
+> 0x0052b420 → `CPhysicsObj::recalc_cross_cells` 0x00515a30). Equivalence is
+> pinned by `CommitTimeRefloodMatchesPrecomputedReflood`; world-size
+> independence by `CollisionPreparationCostIsIndependentOfResidentWorldSize`.
+> Residual timing/order compression vs retail: AD-62.
+
+### 1b. New row AD-62 (residual timing/order compression), adaptation class
+
+| AD-62 | **Adaptation.** Commit-time collision reflood granularity/order: retail runs `CObjCell::init_objects` per CELL at cell hydration and `CPhysicsObj::recalc_cross_cells` per object as each cell loads; acdream runs the equivalent once per LANDBLOCK replacement inside the single synchronous activation call, walking the sealed owner list then the live prefix-owner slots (per-landblock granularity matches the streaming unit, same compression `ShadowObjectRegistry.RefloodLandblock` has always carried). An owner becoming target-associated mid-publication refloods at activation (the prefix-slot sweep) rather than at its own cell's hydration instant; a stationary owner adjacent to the target whose flood would only change through building/EnvCell bridges can carry frame-stale cross-cells between the seal capture and the activation sweep (movers self-heal per `SetPositionInternal`). | `src/AcDream.Core/Physics/PhysicsEngine.cs` (`CommitLandblockReplacement`); `src/AcDream.Core/Physics/ShadowObjectRegistry.cs` (`ApplyCommittedOwnerReplacement`, `RefloodPrefixOwnersAfterReplacement`) | Late/stale cross-cell rows for a non-moving seam object for a few frames around a landblock publication — an object collidable through a wall seam or briefly not collidable where new topology landed | Low | `CObjCell::init_objects` 0x0052b420; `CPhysicsObj::recalc_cross_cells` 0x00515a30; `CPhysicsObj::SetPositionInternal` tail 0x00515330 |
+
+---
+
+## 2. `claude-memory/project_physics_collision_digest.md` — DO-NOT-RETRY additions
+
+> - **Do not re-introduce a whole-world staging clone for collision
+>   generations.** The atomic unit is the landblock delta applied in one
+>   update-thread call (`PhysicsEngine.CommitLandblockReplacement`); the
+>   runtime is single-threaded and a root swap buys nothing. The clone made
+>   ring load O(N²) (the C3c late-monster-pop-in / stuck-portal-space soak
+>   failure, issue #280). Deleted 2026-08-02.
+> - **Batching N staging-clone leaves per step is not a fix** — measured 1.8×
+>   at N=256, not convergence, and it trips the committed one-work-unit seal
+>   invariant. The fix was removing the clone, not tuning it.
+
+## 3. `docs/research/2026-07-31-atomic-collision-generation.md` — update
+
+Add a banner at the top:
+
+> **SUPERSEDED IN PART (2026-08-02).** Steps 2 (whole-world staging clone), 3
+> (owner-mutation journal write-through), 5 (journal coalescing/compaction), 6
+> (peer rebases), 7 (draft retirement cursors), and 8 (whole-root transfer)
+> describe machinery deleted by the collision publication-throughput fix
+> (O1/O2/O3). The atomicity requirement they served — "the multi-frame build
+> must not be observable" — is now met by one synchronous per-landblock delta
+> apply under prefix quiescence with commit-time owner refloods against the
+> live world (retail init_objects → recalc_cross_cells). The admission
+> fairness half (quiescence, prefix mutation permissions, ordered activation)
+> is unchanged and still accurate. Deterministic-evidence entries that name
+> the journal/rebase/retirement tests refer to tests deleted with the
+> machinery; their replacements are
+> `CollisionPreparationCostIsIndependentOfResidentWorldSize`,
+> `CommitAppliesOneLandblockDeltaInASingleCall`, and
+> `CommitTimeRefloodMatchesPrecomputedReflood`.
+
+## 4. `memory/project_collision_port.md`
+
+Remove/replace the 37-line block `6b28ff99` added (the starvation-free clone
+description) with a pointer to the new mechanism (same content as 1a).
+
+## 5. `docs/ISSUES.md` — file the regression as its own issue
+
+> - **#280 — OPEN → fixed pending review: collision staging clone made ring
+>   load O(N²)** (filed 2026-08-02). The per-publication whole-world staging
+>   clone (be94bc9b synchronous, 6b28ff99 metered) plus the seal's full-map
+>   scans cost ~2-3× resident world per landblock publication, so an
+>   N-landblock ring cost O(N²) and the far ring never converged. F4 measured
+>   median 19,736 leaves / 3.64 ms per publication; C3c made it user-visible
+>   (late monster pop-in, extended/stuck portal space, portal-exit pop-in,
+>   nine-stop soak failure 20260802-143157) but did not cause it. Fix: O1
+>   per-prefix installed-key ledger; O2 per-landblock delta commit
+>   (restores be94bc9b's O(changed) apply); O3 empty staging root +
+>   commit-time reflood (retail init_objects → recalc_cross_cells) + journal/
+>   rebase/retirement machinery deleted. Reference the O1/O2/O3 commits here
+>   when they land.
+
+## 6. Milestones/roadmap
+
+No phase-table change needed: this is Modern Runtime infrastructure follow-up
+inside the active campaign context; the C3c smoke-test findings list in
+ISSUES (#278 additions) should get items (d)/(e)/(f)-class re-observed after
+the soak gate passes.
+
+## 7. Commit-message notes for the slice commits
+
+- O1: `fix(physics): #280 O1 - per-prefix installed-key ledger; seal scans and
+  landblock removals become O(prefix keys)` — behavior-identical; new test
+  CollisionSealWorkIsIndependentOfResidentWorldSize.
+- O2: `fix(physics): #280 O2 - restore per-landblock delta commit (be94bc9b
+  shape) at PhysicsEngine.CommitLandblockReplacement` — notes: staging-slot
+  owner-list widening (direct-staged owners), staging-root revoke, zero-byte
+  commit asserts → O(target payload) bounds (commit-time reflood + dictionary
+  node inserts allocate; world-size independence pinned by the O3 test).
+- O3: `fix(physics): #280 O3 - empty staging root; commit-time reflood
+  (init_objects → recalc_cross_cells); delete journal/rebase/retirement
+  machinery` — 9 mechanism tests deleted, 2 contract tests added.