docs(physics): record cutover slice C0 completion

C0 landed at 67f63e85 with dual review PASS; the plan now records its
delivered seam (acknowledge-only ExecutorCompleted receipts through the
one placement stream, retail-exact live-input derivation, the chained
authored-mover preparation, the cancellation-symmetry hardening) and the
three C3 prerequisites its reviews surfaced: the internal-only completion
receipt surface, the per-Execute distance-freshness deferral, and the
SendAutonomyLevelEvent obligation on any future autonomy-level host
exposure. Next slice: C1, the atomic controller/body publication.

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

docs/plans/2026-08-02-placement-cutover.md

@@ -47,12 +47,33 @@ same commit) → docs/handoff commit. No workarounds; no fused slices.
 
 ## Slices
 
-- **C0 — Runtime bridge + live inputs (dormant).** Publish executor
-  adoption/completion through `Placements` as the receipt stream hosts
-  consume; derive `UsePositionFromServer`/`PlayerDistance` inside Runtime
-  from its own owners (no host-supplied gameplay inputs); wire the
-  exact-Setup mover chain end-to-end for the initial-Create placement; fix
-  the route-7 cancellation asymmetries. Still no production caller.
+- **C0 — Runtime bridge + live inputs — COMPLETE at `67f63e85`
+  (2026-08-02, dual reviews PASS).** The executor publishes an
+  acknowledge-only `ExecutorCompleted` receipt through the one placement
+  stream (registered before dispatch; correlation reaped on
+  acknowledgement/discard/clear; `PendingCompletionReceiptCount` in
+  `IsConverged`); all three production sinks acknowledge-and-ignore the
+  kind via early returns proven behavior-preserving for every other kind
+  (sanctioned seam completion — provably inert, no production publisher);
+  `UsePositionFromServer` derives retail-exactly from
+  `RuntimeCharacterState.AutonomyLevel != 2` and `PlayerDistance` from the
+  live movement controller with null-safe fallback to the caller struct;
+  `TryPrepareAndSubmitAuthoredPlacement` chains the prepared-collision
+  Setup read through `PrepareMover` to submission with zero validation
+  changes; `TryCommitParent`/`CommitWithdrawal` gained the sibling
+  cancellation flow (the `LeaveWorld` omission in `TryCommitParent` is
+  retail-REQUIRED per `set_parent` 0x00515A90:283832-283833's single gated
+  `leave_world`). Not fully dormant by design: the two cancellation fixes
+  change live Runtime paths production already calls; everything else has
+  no production caller.
+  **C3 prerequisites recorded from C0's reviews:** (a) the completion
+  receipt/trace surface is internal-only — C3 must define the public host
+  consumption shape when it wires the hosts; (b) `PlayerDistance` is
+  resolved once per `Execute` entry, not per continuation — a multi-Position
+  FIFO classifies later entries against entry-time distance (documented
+  deferral; refine at C3/C4 if the connected gates show it matters);
+  (c) any future host exposure of `TrySetAutonomyLevel` must carry retail's
+  `SendAutonomyLevelEvent` (699550).
 - **C1 — atomic controller/body publication (prerequisite C).** One
   Runtime-owned transaction publishing the exact same canonical body to
   graphical and no-window controllers, prepared off-canonical, committed