fix(vendor): re-gate residuals — MaxStackSize is the stack operand, wire-authored use radius, purse summaries

R1 the split bar's operand is the item's authored MaxStackSize —
three retail sites read pwd._maxStackSize directly (InqListSlotCount
pc:200052, buy-button cases pc:203996/204086) where ACE never fills
the desc stack and standard stock is unlimited. Threaded StackSizeMax
end to end with one shared resolver; the two literal _maxStackSize
sites are now byte-exact; AP-165 retired, AP-169 corrected.
R2 walk-to-vendor never opened because GetUseRadius used an UNCITED
3m Creature heuristic as the local stop distance while ACE's poll
demands the authored radius (default 0.6 m) — the walk stopped and
the Use fired far outside acceptance. Now reads the wire-authored
spawn UseRadius with ACE's exact fallback; heuristic constants
deleted. A first sabotage attempt was non-discriminating
(coincidental 0.6) and was corrected — the discriminating version is
what landed.
R3 the Buying/Selling purse summaries ("Buying %d %s worth %hsp" /
"You have %hsp") recovered from the binary data segment where BN
mis-attributes the Buy-side literal; wired to staging and money
changes on the four authored text elements; AP-166 narrowed to the
pending-sell highlight.

Clean-room complete solution: 11,528 passed / 4 skipped / 0 failed.

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

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

@@ -117,21 +117,28 @@ public sealed class VendorShopItemMaterializerTests
     }
 
     /// <summary>
-    /// G2 (grand-gate finding): a REAL ACE vendor listing carries
+    /// R1 gate-finding fix (2026-08-08, register AP-169 correction,
+    /// replacing the retired <c>Apply_NoDescStackSize_FallsBackToPackedSupplyCount</c>
+    /// G2 test below). A REAL ACE vendor listing for an UNLIMITED-STOCK
+    /// stackable item (e.g. a Prismatic Taper) carries
     /// <c>DescStackSize=null</c> (ACE's <c>Vendor.LoadInventoryItem</c> never
-    /// calls <c>wo.SetStackSize</c> on the browse-list WorldObject) and only
-    /// the packed <see cref="VendorShopItem.StackSize"/> supply-count field
-    /// (<c>VendorShopCreateListStackSize</c>) names a real quantity. Before
-    /// the fix, <c>ToWeenieData</c> read only <c>DescStackSize</c>, so
-    /// <see cref="ClientObject.StackSize"/> came back 1 for every vendor
-    /// item — the toolbar split slider (which gates on
-    /// <c>stackSize &gt; 1</c>) never appeared for ANY vendor stack. This
-    /// pins the fallback: no <c>DescStackSize</c>, packed
-    /// <c>StackSize=100</c> -&gt; <c>ClientObject.StackSize</c> resolves to
-    /// 100, not 1.
+    /// calls <c>wo.SetStackSize</c> on the browse-list WorldObject) AND the
+    /// packed <see cref="VendorShopItem.StackSize"/> supply-count field at
+    /// its UNLIMITED sentinel (<c>-1</c>) — so neither wire "how many"
+    /// signal names a usable ceiling. The G2 fix's packed-supply-count
+    /// fallback (the ORIGINAL version of this test) produced nothing usable
+    /// for exactly this case — a live re-test confirmed the toolbar split
+    /// bar stayed hidden, matching the live retail screenshot report (see
+    /// AP-169's corrected story). This pins the CORRECT fallback:
+    /// <see cref="VendorShopItem.MaxStackSize"/> — the item TYPE's authored
+    /// stack ceiling, which ACE DOES reliably populate (an ordinary weenie
+    /// property, not an instance-specific "how many for sale" count) — no
+    /// <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.
     /// </summary>
     [Fact]
-    public void Apply_NoDescStackSize_FallsBackToPackedSupplyCount()
+    public void Apply_UnlimitedStockNoDescStackSize_FallsBackToMaxStackSize()
     {
         var vendor = new VendorState();
         var objects = new ClientObjectTable();
@@ -140,21 +147,27 @@ public sealed class VendorShopItemMaterializerTests
         vendor.Apply(VendorGuid, default, new[]
         {
             new VendorShopItem(
-                ItemA, StackSize: 100, WeenieClassId: 1u, Name: "Arrow",
-                ItemType: (uint)ItemType.MissileWeapon, IconId: 0x1234u, Value: 100,
-                DescStackSize: null),
+                ItemA, StackSize: -1, WeenieClassId: 1u, Name: "Prismatic Taper",
+                ItemType: (uint)ItemType.SpellComponents, IconId: 0x1234u, Value: 100,
+                DescStackSize: null, MaxStackSize: 1000),
         });
 
-        Assert.Equal(100, objects.Get(ItemA)!.StackSize);
+        ClientObject item = objects.Get(ItemA)!;
+        Assert.Equal(1000, item.StackSize);
+        Assert.Equal(1000, item.StackSizeMax);
     }
 
     /// <summary>
-    /// G2 companion: the packed field's -1 "unlimited supply" sentinel has
-    /// no bounded per-row purchase cap in the wire shape today, so it must
-    /// fall through to the safe non-splittable default (1) rather than
-    /// literally propagating -1 (which would read as a huge unsigned
-    /// "stack size" to <see cref="SelectedObjectController"/>'s
-    /// <c>stackSize &gt; 1</c> gate).
+    /// Sabotage-adjacent control: the SAME unlimited-stock listing but with
+    /// <see cref="VendorShopItem.MaxStackSize"/> ALSO absent (neither wire
+    /// "how many" signal usable at all) still degrades to the safe
+    /// non-splittable default (1) rather than literally propagating the
+    /// packed field's <c>-1</c> sentinel (which would read as a huge
+    /// unsigned "stack size" to <c>SelectedObjectController</c>'s
+    /// <c>stackSize &gt; 1</c> gate). Proves
+    /// <see cref="Apply_UnlimitedStockNoDescStackSize_FallsBackToMaxStackSize"/>'s
+    /// 1000 result comes from the MaxStackSize field specifically, not from
+    /// some other code path that would resolve to 1000 regardless.
     /// </summary>
     [Fact]
     public void Apply_UnlimitedSupplySentinel_FallsBackToNonSplittableDefault()
@@ -163,7 +176,7 @@ public sealed class VendorShopItemMaterializerTests
         var objects = new ClientObjectTable();
         using var materializer = new VendorShopItemMaterializer(vendor, objects);
 
-        vendor.Apply(VendorGuid, default, new[] { Item(ItemA, "Bread") }); // StackSize: -1, DescStackSize: null
+        vendor.Apply(VendorGuid, default, new[] { Item(ItemA, "Bread") }); // StackSize: -1, DescStackSize: null, MaxStackSize: null
 
         Assert.Equal(1, objects.Get(ItemA)!.StackSize);
     }