fix #174: RemoveLinkAnimations seam is HandleEnterWorld (strip + drain)

Retail CPhysicsObj::RemoveLinkAnimations (0x0050fe20) is a tailcall to
CPartArray::HandleEnterWorld (0x00517d70) -> MotionTableManager::
HandleEnterWorld (0x0051bdd0): remove_all_link_animations PLUS a full
pending_animations drain (while (head) AnimationDone(0)), each pop
relaying MotionDone so CMotionInterp pops its pending_motions node in
lockstep. acdream bound the seam to the bare sequence strip, so every
jump's LeaveGround removed the animations that queued manager nodes
were counting down on — orphaning them (NumAnims>0, anims gone) and
permanently damming BOTH queues. MotionsPending() then never drained
(probe round: last player pending=False at the first MovementJump
press; old jump motions still completing at rest minutes later) and
BeginTurnToHeading/BeginMoveForward's verbatim motions_pending gates
starved every armed moveto: ACE's mt-6 walk-to-door armed but the body
never walked (wire-proven, seqs 98-101); the close-range use turn
never completed so the deferred action was silently eaten. Doors only
worked on a fresh session (shallow queue).

Rebind both production sites (remote EnsureRemoteMotionBindings +
the player's EnterPlayerModeNow block) to Manager.HandleEnterWorld();
the sequencer wrapper was a pure passthrough so the manager call is a
strict superset. All six interp seam sites (LeaveGround, HitGround,
Dead, and the detached-object guards) are the same retail chain.
Harness mirrors updated; pins: Issue174LinkStripDrainTests (the seam
drains both queues; fresh motions queue and complete after). Suites:
Core 2535 / App 713 / UI 425 / Net 385 green.

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

tests/AcDream.Core.Tests/Physics/Motion/Issue174LinkStripDrainTests.cs

@@ -0,0 +1,97 @@
+using AcDream.Core.Physics;
+using AcDream.Core.Physics.Motion;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace AcDream.Core.Tests.Physics.Motion;
+
+// ─────────────────────────────────────────────────────────────────────────────
+// #174 pin (2026-07-05): the RemoveLinkAnimations seam must be retail
+// CPhysicsObj::RemoveLinkAnimations 0x0050fe20 — a TAILCALL to
+// CPartArray::HandleEnterWorld 0x00517d70 → MotionTableManager::
+// HandleEnterWorld 0x0051bdd0: CSequence::remove_all_link_animations PLUS a
+// full pending_animations drain (`while (head) AnimationDone(0)`), each pop
+// relaying MotionDone → CMotionInterp pops its pending_motions node in
+// lockstep.
+//
+// The pre-fix binding was the bare sequence strip: every LeaveGround (jump)
+// removed the link animations that queued MotionTableManager nodes were
+// counting down on, orphaning them (NumAnims > 0, animations gone). Both
+// queues then dammed permanently — MotionsPending() never drained at rest —
+// and BeginTurnToHeading/BeginMoveForward (retail 0x00529b90 motions_pending
+// gate) starved every armed moveto: ACE's walk-to-door mt-6 armed but the
+// body never walked; the close-range Use turn never completed so the
+// deferred action was silently eaten. Live evidence: launch-174-autowalk.log
+// (last player pending=False at the first MovementJump press; old jump
+// motions still completing at rest minutes later).
+// ─────────────────────────────────────────────────────────────────────────────
+public class Issue174LinkStripDrainTests
+{
+    private readonly ITestOutputHelper _out;
+    public Issue174LinkStripDrainTests(ITestOutputHelper output) => _out = output;
+
+    /// <summary>
+    /// The jam repro: queue motions (link + cycle nodes land in BOTH the
+    /// interp's pending_motions and the manager's pending_animations), then
+    /// fire the LeaveGround-side seam. With the retail HandleEnterWorld
+    /// binding both queues drain to empty; the pre-fix bare-strip binding
+    /// left both non-empty forever.
+    /// </summary>
+    [Fact]
+    public void RemoveLinkAnimationsSeam_DrainsBothQueues()
+    {
+        var h = new RemoteChaseHarness(_out);
+
+        // Drive a motion burst — walk, run, stop — the shape a player's
+        // pre-jump input produces. Each successful dispatch pairs an interp
+        // node with a manager node.
+        var p = new MovementParameters();
+        h.Interp.DoMotion(MotionCommand.WalkForward, p);
+        h.Interp.set_hold_run(true, interrupt: false);
+        h.Interp.StopMotion(MotionCommand.WalkForward, p);
+
+        Assert.True(h.Interp.MotionsPending(),
+            "precondition: the burst must leave pending interp nodes");
+        Assert.NotEmpty(h.Seq.Manager.PendingAnimations);
+
+        // The LeaveGround seam (retail CMotionInterp::LeaveGround 0x00528b00
+        // fires CPhysicsObj::RemoveLinkAnimations).
+        h.Interp.RemoveLinkAnimations!.Invoke();
+
+        Assert.False(h.Interp.MotionsPending(),
+            "HandleEnterWorld's drain must pop every pending interp node " +
+            "(retail: each AnimationDone(0) relays MotionDone)");
+        Assert.Empty(h.Seq.Manager.PendingAnimations);
+    }
+
+    /// <summary>
+    /// The post-jump livability pin: after the seam fires mid-activity, a
+    /// NEW moveto-style dispatch must be able to queue and complete — the
+    /// #174 symptom was that BeginTurnToHeading's motions_pending gate never
+    /// re-opened after a jump, permanently starving armed movetos.
+    /// </summary>
+    [Fact]
+    public void AfterSeamDrain_NewMotionsQueueAndComplete()
+    {
+        var h = new RemoteChaseHarness(_out);
+        var p = new MovementParameters();
+
+        // Pre-jump activity, then the jump's LeaveGround strip+drain.
+        h.Interp.DoMotion(MotionCommand.WalkForward, p);
+        h.Interp.RemoveLinkAnimations!.Invoke();
+        Assert.False(h.Interp.MotionsPending());
+
+        // A fresh dispatch (the armed moveto's turn) queues...
+        h.Interp.DoMotion(MotionCommand.TurnRight, p);
+        Assert.True(h.Interp.MotionsPending());
+
+        // ...and the normal completion path (the manager's queue feeding
+        // MotionDone) drains it — the gate re-opens.
+        while (h.Seq.Manager.PendingAnimations.GetEnumerator() is var e && e.MoveNext())
+            h.Seq.Manager.AnimationDone(success: true);
+
+        h.Seq.Manager.CheckForCompletedMotions();
+        Assert.False(h.Interp.MotionsPending(),
+            "the normal AnimationDone → MotionDone chain must drain the new node");
+    }
+}

tests/AcDream.Core.Tests/Physics/Motion/RemoteChaseEndToEndHarnessTests.cs

@@ -174,7 +174,10 @@ internal sealed class RemoteChaseHarness
             TurnStopped = () => ObservedOmega = Vector3.Zero,
         };
         Interp.DefaultSink = Sink;
-        Interp.RemoveLinkAnimations = Seq.RemoveAllLinkAnimations;
+        // #174: production binds the seam to Manager.HandleEnterWorld
+        // (strip + full queue drain, retail 0x0050fe20 → 0x0051bdd0) —
+        // the bare sequence strip orphaned pending manager nodes.
+        Interp.RemoveLinkAnimations = () => Seq.Manager.HandleEnterWorld();
         Interp.InitializeMotionTables = () => Seq.Manager.InitializeState();
         Interp.CheckForCompletedMotions = Seq.Manager.CheckForCompletedMotions;