fix(vendor): evidence-based pass — max-first stack ceiling; the local player resolves never-animated MoveTo targets

Both chains pinned by the live [vendor-diag] run (vendor-diag.log)
after three code-reading rounds each failed:

The split bar: ACE serializes descStackSize=1 for EVERY browse row
(live wire, log 343-348) — the R1-era "ACE never populates desc"
claim is retracted with the line quoted. Retail's vendor sites read
pwd._maxStackSize directly (four sites, incl. UpdateItemsList
@0x004c1ea0 stamping min(remaining, _maxStackSize));
ResolveAuthoredStackSize flips to max-first for its vendor-only
consumers. Taper ceiling 1000, scarab 100, seed 1 for exempt.
Pricing still reads the desc (per-1 values on ACE).

Walk-to-use: the local player's getObjectA seam was bound to
TryGetPhysicsHost, which resolves only INSTALLED physics hosts — a
never-animated vendor has none, so TargetManager.SetTarget got null,
the MoveToObject armed with zero nodes, and UseTime never dispatched.
The log's natural=False completions were the user's own movement keys
(retail-correct input-edge cancels); attempt 4 worked because the
greeting animation had installed a host. RuntimePhysicsState gains
the retail CObjectMaint::GetObjectA seam (bound canonical resolver
with installed-host fallback); the graphical host binds the SAME
lazy-minimal-host resolver every remote already uses — whose own doc
comment names this exact never-animated hazard. The reservation
release was already correct (2b premise refuted with evidence); the
production-wiring invariants are now pinned by four new tests
including the pre-fix pathology as a permanent sabotage control.

AP-169 rewritten a second time, honestly. The [vendor-diag] probe
family (ACDREAM_DUMP_VENDOR) lands env-gated for future live triage.

Clean-room complete solution: 11,536 passed / 4 skipped / 0 failed.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/AcDream.App/Interaction/SelectionInteractionController.cs

@@ -173,10 +173,17 @@ internal sealed class SelectionInteractionController
         // Use. Equipped-child picking makes that click reachable, so the gate
         // ships with it.
         if (useImmediately && !_query.IsWieldedByPlayer(guid))
+        {
+            if (VendorDiagnostics.DumpVendorEnabled)
+            {
+                Console.WriteLine(
+                    $"[vendor-diag] route=dblclick-world PickAndStoreSelection guid=0x{guid:X8} enqueue=Activate");
+            }
             EnqueueIdentityBound(
                 RuntimeQueuedInteractionKind.Activate,
                 guid,
                 requireLiveEntity: true);
+        }
     }
 
     /// <summary>
@@ -205,6 +212,11 @@ internal sealed class SelectionInteractionController
             _toast?.Invoke("Nothing selected");
             return;
         }
+        if (VendorDiagnostics.DumpVendorEnabled)
+        {
+            Console.WriteLine(
+                $"[vendor-diag] route=keyboard-use UseCurrentSelection guid=0x{selected:X8} enqueue=Use");
+        }
         EnqueueIdentityBound(
             RuntimeQueuedInteractionKind.Use,
             selected,
@@ -260,10 +272,22 @@ internal sealed class SelectionInteractionController
         bool ownedByPlayer = _items.IsOwnedByPlayer(serverGuid);
         bool useable = ownedByPlayer || _query.IsUseable(serverGuid);
 
+        if (VendorDiagnostics.DumpVendorEnabled)
+        {
+            Console.WriteLine(
+                $"[vendor-diag] RequestUse entry guid=0x{serverGuid:X8} ownedByPlayer={ownedByPlayer} useable={useable}");
+        }
+
         if (useable
             && _query.TryGetApproach(serverGuid, out InteractionApproach approach)
             && !approach.IsCloseRange)
         {
+            if (VendorDiagnostics.DumpVendorEnabled)
+            {
+                Console.WriteLine(
+                    $"[vendor-diag] RequestUse guid=0x{serverGuid:X8} branch=approach-armed useRadius={approach.UseRadius} isCloseRange={approach.IsCloseRange}");
+            }
+
             // Genuinely out of range (a real walk, not just a turn) —
             // mirror SendPickup's arrival-gated shape: arm the transaction
             // on the approach token BEFORE the movement starts (so a
@@ -283,7 +307,17 @@ internal sealed class SelectionInteractionController
                             token.ControllerLifetime,
                             token.ApproachGeneration),
                         out _);
+                    if (VendorDiagnostics.DumpVendorEnabled)
+                    {
+                        Console.WriteLine(
+                            $"[vendor-diag] TryArmPostArrivalUse guid=0x{serverGuid:X8} armed={armed} approachToken=({token.ControllerLifetime},{token.ApproachGeneration})");
+                    }
                 });
+            if (VendorDiagnostics.DumpVendorEnabled)
+            {
+                Console.WriteLine(
+                    $"[vendor-diag] BeginApproach-result guid=0x{serverGuid:X8} started={started} armed={armed} stopDistance={approach.UseRadius} target=0x{approach.Target.ServerGuid:X8}");
+            }
             if (!started || !armed)
             {
                 // Release whatever got captured (or the caller's own
@@ -306,6 +340,11 @@ internal sealed class SelectionInteractionController
         // — keep retail's immediate send; ACE's own "already within use
         // distance" branch (Player_Move.cs:65-87) calls back synchronously,
         // so there is no arrival gap to race here.
+        if (VendorDiagnostics.DumpVendorEnabled)
+        {
+            Console.WriteLine(
+                $"[vendor-diag] RequestUse guid=0x{serverGuid:X8} branch=immediate-dispatch ownedByPlayer={ownedByPlayer} useable={useable}");
+        }
         RuntimeInteractionDispatchResult result =
             _transactions.TryDispatchUse(
                 serverGuid,
@@ -314,6 +353,11 @@ internal sealed class SelectionInteractionController
                 reservation,
                 _transport,
                 out uint sequence);
+        if (VendorDiagnostics.DumpVendorEnabled)
+        {
+            Console.WriteLine(
+                $"[vendor-diag] RequestUse guid=0x{serverGuid:X8} TryDispatchUse verdict={result} seq={sequence}");
+        }
         if (result == RuntimeInteractionDispatchResult.NotInWorld)
             _toast?.Invoke("Not in world");
         if (result == RuntimeInteractionDispatchResult.Dispatched)
@@ -545,6 +589,22 @@ internal sealed class SelectionInteractionController
         RuntimePendingUse pending,
         bool accepted)
     {
+        if (VendorDiagnostics.DumpVendorEnabled)
+        {
+            // Diagnostic-only re-query — TryGetApproach is a pure read with
+            // no side effects, so an extra call here (gated off in
+            // production) cannot change RequestUse's own dispatch outcome.
+            string distanceText = "n/a";
+            if (_query.TryGetApproach(pending.ServerGuid, out InteractionApproach diagApproach))
+            {
+                float dx = diagApproach.Target.Entity.Position.X - diagApproach.Player.Position.X;
+                float dy = diagApproach.Target.Entity.Position.Y - diagApproach.Player.Position.Y;
+                distanceText = MathF.Sqrt(dx * dx + dy * dy).ToString("F2");
+            }
+            Console.WriteLine(
+                $"[vendor-diag] HandleUseApproachCompletion guid=0x{pending.ServerGuid:X8} accepted={accepted} playerToTargetDist={distanceText}");
+        }
+
         if (!accepted)
         {
             pending.Reservation?.CancelBeforeDispatch();