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>

tests/AcDream.Runtime.Tests/Gameplay/VendorShopItemMaterializerTests.cs

@@ -136,6 +136,11 @@ public sealed class VendorShopItemMaterializerTests
     /// <c>DescStackSize</c>, packed <c>StackSize=-1</c> (unlimited),
     /// <c>MaxStackSize=1000</c> -&gt; <c>ClientObject.StackSize</c> resolves
     /// to 1000, not 1 and not the (nonsensical, unbounded) packed field.
+    /// (Second correction, 2026-08-08: the live wire showed ACE actually
+    /// sends <c>descStackSize=1</c>, so <c>MaxStackSize</c> is now the
+    /// PRIMARY operand rather than a fallback — see
+    /// <see cref="Apply_LiveAceWireShape_DescOneMaxHundred_ResolvesToTheAuthoredCeiling"/>;
+    /// this desc-absent case resolves identically either way.)
     /// </summary>
     [Fact]
     public void Apply_UnlimitedStockNoDescStackSize_FallsBackToMaxStackSize()
@@ -157,6 +162,42 @@ public sealed class VendorShopItemMaterializerTests
         Assert.Equal(1000, item.StackSizeMax);
     }
 
+    /// <summary>
+    /// 2026-08-08 live-evidence re-fix (register AP-169, second
+    /// correction): the EXACT wire shape the vendor-diag run captured from
+    /// the live ACE server — `descStackSize=1 stackSizeMax=100` for every
+    /// browse row (e.g. the Smelting Pot / Lead Scarab rows,
+    /// `[vendor-diag] ApproachVendor wire-item[0] ... descStackSize=1
+    /// stackSizeMax=100`). ACE DOES serialize the instance stack size, at
+    /// the useless value 1, so the R1 desc-first preference resolved every
+    /// vendor stack to 1 and the toolbar split slider never appeared
+    /// (`ApplySelection ... failingPredicate=stackSize&lt;=1u`). Retail's
+    /// own vendor UI reads <c>pwd._maxStackSize</c> directly
+    /// (<c>VendorItemsUI::UpdateItemsList</c> <c>0x004c1ea0</c>,
+    /// <c>pc:201085-201133</c>), so the materialized ceiling must be 100
+    /// here. Sabotage-verified: restoring the desc-first preference makes
+    /// this resolve 1 and fail.
+    /// </summary>
+    [Fact]
+    public void Apply_LiveAceWireShape_DescOneMaxHundred_ResolvesToTheAuthoredCeiling()
+    {
+        var vendor = new VendorState();
+        var objects = new ClientObjectTable();
+        using var materializer = new VendorShopItemMaterializer(vendor, objects);
+
+        vendor.Apply(VendorGuid, default, new[]
+        {
+            new VendorShopItem(
+                ItemA, StackSize: -1, WeenieClassId: 1u, Name: "Lead Scarab",
+                ItemType: (uint)ItemType.SpellComponents, IconId: 0x1234u, Value: 10,
+                DescStackSize: 1, MaxStackSize: 100),
+        });
+
+        ClientObject item = objects.Get(ItemA)!;
+        Assert.Equal(100, item.StackSize);
+        Assert.Equal(100, item.StackSizeMax);
+    }
+
     /// <summary>
     /// Sabotage-adjacent control: the SAME unlimited-stock listing but with
     /// <see cref="VendorShopItem.MaxStackSize"/> ALSO absent (neither wire