fix(ui): vendor dropdown polish — authored arrow-cap with open/closed flip, downward popup, left-aligned rows

Three gate findings, each settled by authored data rather than
invention: the button face is retail's two-piece assembly and the
17x19 arrow-cap 0x1000034E now renders with its authored
Normal(closed)/Highlight(open) states; the popup direction is an
AUTHORED attribute (UIElement_Menu::Open pc:120210-120252 — bool
attr 5, chat authors upward=true, the vendor menu authors nothing and
defaults downward), so both menus are now byte-faithful with no
special case; and the 19/20px text indents were chat-specific
checkbox/LED clearances the vendor rows don't author — measured
against the live retail font, "Spell Components" overflowed by 11px
and now fits with 8px to spare. Chat's menu defaults are bit-identical
and its tests untouched.

AP-161's arrow-cap note closes. #351 files the pre-existing FarLoad
Debug flake (three sightings today, never in clean-room Release).

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

tests/AcDream.App.Tests/UI/Layout/VendorUiControllerTests.cs

@@ -822,11 +822,14 @@ public sealed class VendorUiControllerTests
         // Food) -> row index 1, column 0. Derive the click point from the
         // widget's own live geometry (mirrors UiMenu.OnEvent's own math)
         // rather than a hardcoded pixel constant.
+        //
+        // G7: the popup opens DOWNWARD (retail authors no bool attribute 5
+        // on 0x100000BF — see the class doc's "G7" paragraph), so its top
+        // sits at the button's own bottom edge (ly = Height), not -OuterH.
         const int border = 5; // RetailChromeSprites.Border (UiMenu's private bevel thickness)
-        float outerH = h.TypeMenu.RowsPerColumn * h.TypeMenu.RowHeight + 2 * border;
         const int targetRow = 1;
         float iy = targetRow * h.TypeMenu.RowHeight + h.TypeMenu.RowHeight / 2f;
-        float ly = iy - outerH + border;
+        float ly = h.TypeMenu.Height + iy + border;
 
         Assert.True(h.TypeMenu.OnEvent(new UiEvent(0, h.TypeMenu, UiEventType.MouseDown, 0, 10, (int)ly)));
 
@@ -834,6 +837,79 @@ public sealed class VendorUiControllerTests
         Assert.Equal(FoodItemGuid, h.ItemList.GetItem(0)!.ItemId);
     }
 
+    [Fact]
+    public void CategoryMenu_OpensDownward_NotUpward_MatchingTheAuthoredAbsentAttribute5()
+    {
+        // G7: retail's UIElement_Menu::Open (pc:120210-120252) reads a PER-MENU
+        // bool attribute 5 to decide direction; it defaults ABSENT to false
+        // (pc:106749-106778) which places the popup at the button's own bottom
+        // edge. Element 0x100000BF's resolved attribute bag carries no
+        // property "5" at all (unlike chat's, which authors it true) — so
+        // OpenUpward must be false here, and the OLD upward click position
+        // (used before this fix) must no longer resolve anything.
+        var h = new Harness();
+        h.State.Apply(VendorGuid, Profile(), new[]
+        {
+            new VendorShopItem(ArmorItemGuid, -1, 2u, "Chainmail", (uint)ItemType.Armor, 200u, 500),
+            new VendorShopItem(FoodItemGuid, -1, 1u, "Bread", (uint)ItemType.Food, 100u, 5),
+        });
+
+        Assert.False(h.TypeMenu.OpenUpward);
+
+        Assert.True(h.TypeMenu.OnEvent(new UiEvent(0, h.TypeMenu, UiEventType.MouseDown, 0, 10, 5)));   // open
+
+        // The OLD (pre-fix) upward click position for row 1 ("Food") — see the
+        // math this same test used before G7 — now lands above the button,
+        // where nothing lives; UiMenu treats it as an ordinary button click
+        // and just re-closes the still-open menu instead of picking a row.
+        const int border = 5;
+        float outerH = h.TypeMenu.RowsPerColumn * h.TypeMenu.RowHeight + 2 * border;
+        const int targetRow = 1;
+        float iy = targetRow * h.TypeMenu.RowHeight + h.TypeMenu.RowHeight / 2f;
+        float oldUpwardLy = iy - outerH + border;
+        Assert.True(h.TypeMenu.OnEvent(new UiEvent(0, h.TypeMenu, UiEventType.MouseDown, 0, 10, (int)oldUpwardLy)));
+
+        // Selection is unchanged (still Armor, the fresh-open default) and the
+        // item list was not re-scoped to Food — proving the old position no
+        // longer hits the popup at all.
+        Assert.Equal("Armor", h.TypeMenu.Items.Single(i => Equals(i.Payload, h.TypeMenu.Selected)).Label);
+        Assert.Equal(ArmorItemGuid, h.ItemList.GetItem(0)!.ItemId);
+    }
+
+    [Fact]
+    public void CategoryMenu_ArrowCapSprites_AreWiredAndDistinctForOpenVsClosed()
+    {
+        // G6: retail's authored arrow-cap element 0x1000034E flips between its
+        // Normal (closed, 0x060012B1) and Highlight (open, 0x060012B2) states —
+        // confirm the controller actually wires both, non-zero and distinct,
+        // and that opening the dropdown flips CurrentArrowCapSprite the same
+        // way UiMenuTests exercises the mechanism generically.
+        var h = new Harness();
+        h.State.Apply(VendorGuid, Profile(), new[]
+        {
+            new VendorShopItem(ArmorItemGuid, -1, 2u, "Chainmail", (uint)ItemType.Armor, 200u, 500),
+        });
+
+        Assert.NotEqual(0u, h.TypeMenu.ArrowCapClosedSprite);
+        Assert.NotEqual(0u, h.TypeMenu.ArrowCapOpenSprite);
+        Assert.NotEqual(h.TypeMenu.ArrowCapClosedSprite, h.TypeMenu.ArrowCapOpenSprite);
+
+        Assert.Equal(h.TypeMenu.ArrowCapClosedSprite, h.TypeMenu.CurrentArrowCapSprite);   // closed by default
+        Assert.True(h.TypeMenu.OnEvent(new UiEvent(0, h.TypeMenu, UiEventType.MouseDown, 0, 10, 5)));   // open
+        Assert.Equal(h.TypeMenu.ArrowCapOpenSprite, h.TypeMenu.CurrentArrowCapSprite);
+    }
+
+    [Fact]
+    public void CategoryMenu_TextIndentsAreFlushLeft_NotChatsCheckboxLedOffsets()
+    {
+        // G8: vendor's row template (0x10000352, live-dat HJustify=Left) has
+        // no checkbox child and its button-label child (0x1000034D) has no
+        // LED art either — both indents must be 0, not chat's 19px/20px.
+        var h = new Harness();
+        Assert.Equal(0f, h.TypeMenu.TextIndent);
+        Assert.Equal(0f, h.TypeMenu.ButtonTextIndent);
+    }
+
     [Fact]
     public void CloseButton_HidesTheWindowOnly_LeavesTheSessionOpenForARefreshInPlaceReopen()
     {