Ports retail's missile Position handling into the canonical Runtime
placement owner instead of the deleted ApplyAuthoritativePosition
short-circuit. The Create/residence-window halves of the projectile
pipeline (RuntimeProjectile binding, TryBind's adopted-body branch,
the collision/shadow registration) were already canonical from prior
slices; this closes the remaining gap — how an ACCEPTED Position for
an in-flight missile is classified, placed, and presented.
Byte-decode (Step 1 hard gate, before any code was written):
CPhysicsObj::MoveOrTeleport @0x00516330-0x00516438 disassembled from
the PDB-paired binary (Capstone, x86 32-bit thiscall). `ret 0x10`
establishes four stack args; [esp+0x7c] (arg5, the velocity pointer)
is never referenced in any of the three branches (teleport/near/far).
The retail reviewer independently reproduced this by searching the
whole function body for the `24 7c` mod/rm+disp8 encoding a
`[esp+0x7c]` read would require and found zero occurrences. This
retired a fabricated `?? Vector3.Zero` fallback in the deleted method
— retail's PositionPack::UnPack initializes an absent velocity to
zero and MoveOrTeleport never installs it; the projectile's Vector
channel (RuntimeProjectilePhysicsUpdater.ApplyAuthoritativeVector)
remains the sole velocity authority for a missile. D-P5 in the
contract; the Runtime seam commits no velocity from the Position
packet at all.
The unbound-missile fix: RuntimeEntityObjectLifetime's
ClassifyRemoteAcceptedPosition now derives ProjectileAuthoritative
from a CONJUNCTIVE predicate — the Missile bit AND a bound
RuntimeProjectile whose Body is the canonical PhysicsBody — never the
bit alone. Retail places every non-player CPhysicsObj unconditionally
(there is no missile-specific placement gate in MoveOrTeleport or its
callers), so an unbindable or not-yet-bound missile taking the
ordinary remote tail is retail-faithful, not a fallback: the earlier
bit-only discriminator would have silently frozen it instead.
AP-141 records this as a deliberate, recorded divergence, not
fidelity. Retail mechanically WOULD arm a missile's ConstrainTo leash
on any nonzero MoveOrTeleport return: HandleReceivedPosition
@0x00453FD0's only kind test is player-vs-not, ConstrainTo
@0x00454272 has no kind test of its own, and CPhysicsObj::ConstrainTo
@0x00510520 creates a PositionManager on demand via
MakePositionManager @0x00510523 if one doesn't exist. acdream
deliberately does not construct that EntityPhysicsHost/
PositionManager/InterpolationManager chain for a ballistic body — the
route-5b split the C4 route 5 contract rejected — so a live missile
never shows an armed leash and never catches up via the near/
UnroutedCatchUp policy. This divergence is safe specifically because
ACE never sends UpdatePosition for a missile
(references/ACE/Source/ACE.Server/WorldObjects/WorldObject_Tick.cs:
333-334, SendUpdatePosition() commented out inside the
PhysicsState.Missile branch at :265) — every half of this row is
deterministic-test-gated only, never exercised against a real server.
AP-141 also records the surviving ConstrainTo re-anchor divergence
under clause (b): for the adopted-body case (TryBind's shared-body
branch — an ordinary remote whose Missile bit is set by a later
State packet, so it still carries a live RemoteMotion), acdream now
ports retail's teleport-branch and far-branch StopInterpolating
action (Interp.Clear()), but never re-arms or re-anchors the
inherited ConstrainTo leash the way retail's HandleReceivedPosition
@0x00454254/@0x00454272 does on every nonzero return. The risk
column's earlier wording — that a stale leash "would drag the body
toward a stale anchor" — was wrong and is retracted in this same
commit: ConstraintManager.ConstraintPos is write-only in both retail
and the port (never read by AdjustOffset), and
ConstraintManager::adjust_offset @0x00556180 only tapers or zeroes an
already-composed per-tick offset while InContact — a leash brakes
motion the interp/sticky chain already produced, it cannot pull
anything toward the anchor. The real residual is one tick of un-reset
brake accumulator, contact-gated, and it cannot move an airborne
far-snapped missile at all (the clamp branch does not run while
airborne).
NO CONNECTED GATE EXISTS for this route, by design: ACE never sends a
missile UpdatePosition (see above), so retail's own server never
exercises this code path in play. Every proof obligation here is
test-gated only — Runtime and App-level fixtures constructing the
packet directly — never a live client/server capture.
Three review rounds closed 8 MAJOR findings before this landed:
round 1 (A1 App discarded the seam's status; A2/R1 silent swallow on
an unbound missile; A3/R2 the adopted-body teleport_hook never
wired; A4/A5 zero Runtime/App test coverage); round 2 (a
ParentCellId regression introduced by round 1's own R6 finding,
which the retail reviewer retracted the following round as factually
wrong — the fix here is the REVERT to record.FullCellId, not the
relocation round 1 shipped; B2 the far-branch StopInterpolating skip
never extended to the adopted-body case; residual App/Runtime store-
path coverage; a per-packet closure contradicting the file's own
#315 cached-delegate pattern). Round 3 closed on coverage alone (no
defect): the Advance() retry arm's projectile branch — added at
round 2, semantically reordered at round 2's B5 fix (skip prediction
invalidation on a re-parked Contention, since it writes nothing) —
had never been executed by any test; two new tests drive it directly
and are sabotage-verified against both the reordering and the
retry-arm's own SyncProjectilePresentation call site. The one
recorded defect this campaign produced (the ParentCellId regression)
was caused by complying with a review finding that its own author
later retracted — the standing lesson recorded for future rounds is
that review findings are evidence to re-verify against the code, not
commands to obey unconditionally.
Complete Release suite: 11,063 passed / 4 skipped / 0 failed
(baseline 11,036 at 30d3d114, +27 new tests across this campaign).
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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>
Erik