C4 route 4b-3 collapse (docs/research/2026-08-04-onposition-collapse-contract.md).
Behaviour-preserving: the ~640-line duplicated player-guid and NPC-guid
copies of the remote routing tail in LiveEntityNetworkUpdateController.OnPosition
become one guid-blind tail, reached by every remote guid through the single
ApplyRemoteContactRouting/RunRemoteArmTail seam.
Two guid-conditionals survive, both named and justified:
- Row 8 (TS-44 sticky suppression, creature-only): retail's sticky is
independent of this acdream-only steady-state gate; the register row
already describes it as NPC-only and this collapse does not widen it.
- The AirborneSnap arm's interp-clear + shadow-publish (rows 2a/2b,
player-only preserve): unifying either way would be an unauthorized
behaviour change. #316 (shadow publish) is a real, unmeasured
pre-existing defect, deliberately preserved not fixed. The interp-clear's
equivalence could not be proven for the steep-non-walkable-landing edge
case (AdjustOffset's CONTACT-keyed gate vs. AP-139's WALKABLE-keyed
per-tick clear) — preserved per contract stop condition 2 rather than
shipped on an incomplete proof.
Category-(c) resolutions (contract §2.1-2.5), each with its evidence:
- Row 2a (interp clear): PRESERVED — AdjustOffset's `if (!inContact) return`
proves inertness on flat landings, but not on the steep-contact edge case.
- Row 2b (shadow publish / #316): PRESERVED — no design note ever sanctioned
the player-guid skip; the file's own #184 Slice 2b comments contradict it.
- Row 2c (EnsureRemoteMotionBindings): UNIFIED — the method is idempotent
(`if (rm.Host is not null) return rm.Sink;`), so "always ensure" is safe.
- Row 3 (wire-cell adopt ordering): UNIFIED — RebucketLiveEntity already
commits the wire cell before either guid branch runs, so the deleted
player-guid pre-write was a proven no-op.
- Row 4 (LastServerPos/Time sample timing): UNIFIED — on a genuine first UP,
InterpolationManager.Enqueue's already-close branch and the Snapped branch
both converge on the same body pose/orientation for a zero-distance target.
- Row 12 (wall-clock capture): UNIFIED — one shared `nowSec`, a
microsecond-scale skew in acdream-only bookkeeping/diagnostics.
Sabotage check (contract §5, performed and reverted, not committed):
deleting the one remaining TryArmConstraintAfterOperation call failed
10/16 dual-guid matrix tests, spanning BOTH guid halves of every
arming-dependent scenario (teleport, landing, near, far, sticky) — proof
the matrix discriminates a defect regardless of which guid range exercises
it, closing the class of bug that let 4b-3's A1/A2/R3 findings survive
review when only one copy's tests were green.
New tests/AcDream.App.Tests/Physics/LiveEntityNetworkOnPositionCollapseMatrixTests.cs
drives 8 scenarios x 2 guid ranges (0x50xxxxxx player, 0x8xxxxxxx creature)
through the complete production OnPosition entry point. Doc comments on
ApplyRemoteContactRouting, RunRemoteArmTail, ApplyWireAirborneLeftoverBookkeeping,
TryAdoptWireCellAfterRouting, and the AirborneNoOperation throw guard
updated to describe the collapsed one-path world (the "two callers stay
one decision" claim was true before this commit and false after — fixed
in the same commit that makes it false). One branch-routing source-text
pin (LiveEntityNetworkBranchRoutingTests.cs) updated to follow the AP-140
CONTACT gate to its new address inside ApplyRemoteContactRouting.
#316 stays OPEN, deliberately not fixed here — see its updated ISSUES.md
entry.
dotnet build AcDream.slnx -c Release: 0 errors. Verified independently
bisectable at this exact commit: AcDream.App.Tests 4104/4107 (3 pre-existing
skips), AcDream.Runtime.Tests 1125/1125.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The two gates that decide whether an accepted remote Position is interpolated
or hard-snapped read `Airborne`, which is `!Body.OnWalkable` — WALKABILITY.
Retail reads CONTACT: InterpolationManager::adjust_offset @0x00555D30 gates its
entire body on `transient_state & 1` @0x00555D52, so a retail body in contact
with a non-walkable face still interpolates.
The two predicates disagree in exactly one state — in contact, not on walkable
ground — which 204d0ae0 turned from unreachable into ordinary. Before it, the
per-tick forge made every non-airborne remote walkable by construction, so the
disagreement could not occur.
Both gates now read `!Body.InContact`: ApplyRemoteContactRouting's flight
carve-out and OnPosition's player-remote arm.
`Airborne` is deliberately NOT re-derived from CONTACT. That would perturb all
five of its writers and contradict a pinned assertion in
RemoteTeleportPlacementTests.Apply_PendingGroundToSteepContact_ (InContact:
true, OnWalkable: false -> Assert.True(remote.Airborne)); a previous
implementer attempted it and correctly backed out rather than editing the
assertion. This narrower shape touches no existing test.
AP-140's register row is retired in this commit, as the row itself specified.
Honest scope: this is a faithfulness fix, not a visible one. ACE derives its
IsGrounded flag with the same floor_z test, so during a slide it almost
certainly reports not-grounded, the classifier returns NoPositionOperation, and
neither arm is taken. Expect no observable change against ACE.
Suite 11,027 passed / 4 skipped / 0 failed (baseline 11,023).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A local-player ForcePosition had TWO independent writers for one accepted
packet: LocalForcePositionTransaction snapped the physics body
(PlayerMovementController.BlipPosition, a raw SnapToCell with no collision
resolve), while LiveEntityNetworkUpdateController's generic tail separately
wrote position/cell/rotation to the render WorldEntity from the raw wire and
rebucketed it. Two stores, one packet — the divergence class 670f307c fixed on
the remote path. The outbound AutonomousPosition ack also fired BEFORE any
canonical commit existed: we told ACE "got it, I'm here" before deciding where
"here" was, and the trailing isCurrent() could only suppress the continuation,
never recall the packet.
RuntimeAcceptedPositionDriveController is now the one Runtime-owned seam. Both
hosts call the identical TryExecuteAcceptedLocalPosition; App and headless
project the committed result through the existing placement projection sink
(LiveEntityRuntime.TryApplyRuntimePlacementPlace already performed the same
four writes, from committed state rather than a wire guess).
Retail: SmartBox::HandleReceivedPosition @0x00453FD0's FORCE_POSITION branch is
get_heading -> Frame::set_heading -> SmartBox::BlipPlayer @0x00453940 -> stamp
POSITION_TS -> SendPositionEvent @0x00454091 -> return @0x0045409D. BlipPlayer
is CPhysicsObj::SetPositionSimple @0x005162B0 with flags 0x1012
(Teleport|Slide|SendPositionEvent) — a real collision-resolving SetPosition,
not a snap. The pinned classifier already encoded this exactly.
Named behaviour changes:
* The ack is now an OUTPUT of the committed route, fired strictly after the
canonical commit and exactly once per accepted force packet.
* The ForcePosition route no longer re-arms the constraint leash. The force
branch returns at 0x0045409D, ahead of all three ConstrainTo sites
(0x00454272, 0x0045418A, 0x004541EC); the old re-arm cited retail's "Player,
normal" branch, which BlipPlayer is not on. The teleport, CommitPreparedPosition
and first-entry callers legitimately still constrain and are untouched.
* A force correction that terminates WITHOUT committing still sends its
position event and is not retried — retail's BlipPlayer discards
SetPositionSimple's SetPositionError return and acks unconditionally.
A single _pending funnel owns the in-flight placement, deciding on the token's
PositionAuthorityVersion against the record's: equal -> clear; advanced with the
newest accepted event still a force -> re-issue, re-classified; advanced to an
ordinary Apply -> clear, since newer server truth owns that pose. This closes a
double-apply/double-ack and a silently-dropped correction that two earlier
iterations of this slice each introduced.
AD-62 records the residual: a ForcePosition our async collision publication
cannot carry to a committed placement is not re-applied. Retail has no park —
its world is fully resident and its placement synchronous — so the state is
unreachable there. AP-131 is NOT retired; its legacy Position caller is route 4.
Deleted: LocalForcePositionTransaction, PlayerMovementController.BlipPosition,
HeadlessSessionWorldProjection.BlipLocalPlayer.
Gates: complete Release solution 10,858 passed / 4 skipped / 0 failed (baseline
10,844/4/0). Two independent Opus reviews (retail-conformance and
architecture/adversarial) PASS on the final diff after three FAIL rounds; every
intermediate state was fully green, so the suite caught none of the four real
defects. Connected acceptance is NOT run: nothing a user can do makes ACE emit
a ForcePosition without retail's @pklite, which acdream does not implement — see
docs/research/2026-08-03-c4-route-2-visual-gate.md.
Known gap, recorded not claimed: the plan's acceptance item 2 is unmet. The App
double-write check is a source pin, and "the committed projection moves the
render entity" is uncovered at any layer (#292). Filed alongside: #286-#291,
#293-#296.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Move Position, Vector, State, Movement, and equal-generation CreateObject routing out of GameWindow while preserving per-channel authority, ForcePosition acknowledgement, and motion-runtime ownership. Add adversarial authority and exact-wire coverage so reentrant updates and GUID reuse cannot publish stale state.
Erik