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>

src/AcDream.App/UI/Layout/VendorUiController.cs

@@ -176,18 +176,68 @@ public sealed class VendorUiController : IRetainedPanelController
     /// literally what vendor's OWN button-face child (<c>0x1000034D</c>)
     /// resolves to in the fixture, and <c>0x060012B4</c> (the row
     /// template's "Highlight" state) is the paired open/pressed look. This
-    /// is a deliberate, bounded choice: retail's actual closed-button
-    /// chrome is a separate two-piece label+arrow assembly
-    /// (<c>0x1000034D</c> label + <c>0x1000034E</c> a 17x19 arrow cap with
-    /// its own Normal/Highlight sprites <c>0x060012B1</c>/<c>0x060012B2</c>),
-    /// and <see cref="UiMenu"/>'s existing single-texture 3-slice
-    /// <c>DrawButtonFace</c> (end caps sized for chat's 46px LED-arrow
-    /// texture) does not model a second overlaid arrow icon. Reworking
-    /// <c>DrawButtonFace</c> into a two-piece label+arrow renderer would
-    /// have meant redesigning UiMenu's draw model for a purely cosmetic
-    /// gain while the actual reported bug (nothing renders at all) is
-    /// fixed by this simpler substitution; the arrow glyph gap is recorded
-    /// as a residual visual approximation (see the register, AP-161).
+    /// remains a deliberate, bounded choice — <see cref="UiMenu"/>'s
+    /// single-texture 3-slice <c>DrawButtonFace</c> (end caps sized for
+    /// chat's 46px LED-arrow texture) is not redesigned into a two-piece
+    /// label+arrow renderer for this plain gold body.
+    /// </para>
+    /// <para>
+    /// <b>G6 (vendor gate finding, item 1 — the missing green arrow
+    /// indicator): closes the arrow-cap half of AP-161's residual.</b>
+    /// Retail's actual closed-button chrome IS a separate two-piece
+    /// label+arrow assembly — label <c>0x1000034D</c> (100x18, HJustify
+    /// LEFT, verified via the fixture) + a SEPARATE 17x19 arrow-cap image
+    /// <c>0x1000034E</c> docked at the button's right edge (X=100,Y=0
+    /// within the 117-wide button), with its own Normal/Highlight states
+    /// resolving to <c>0x060012B1</c> (closed)/<c>0x060012B2</c> (open) —
+    /// verified live via <c>tools/VendorLayoutScan</c>'s <c>resolved</c>
+    /// command reading the element's two StateMedia images directly out of
+    /// <c>client_local_English.dat</c>. <see cref="UiMenu.ArrowCapClosedSprite"/>/
+    /// <see cref="UiMenu.ArrowCapOpenSprite"/> draw this AS AN OVERLAY on top
+    /// of the existing 3-slice body (additive, not a DrawButtonFace rewrite)
+    /// so the green arrow now flips down (closed)/up (open) exactly like
+    /// retail, without touching chat's face (whose arrow is baked into its
+    /// own texture and never sets these).
+    /// </para>
+    /// <para>
+    /// <b>G7 (vendor gate finding, item 2 — the popup opened upward instead
+    /// of downward).</b> Retail's <c>UIElement_Menu::Open</c>
+    /// (<c>pc:120210-120252</c>, <c>0x0046cc30</c>) places the popup at
+    /// <c>ScreenY1(button)</c> (the button's own BOTTOM edge — i.e. BELOW
+    /// it) unless the menu authors bool attribute 5 true, in which case it
+    /// places it at <c>ScreenY0(button) - popupHeight</c> (ABOVE).
+    /// <c>UIElement::GetAttribute_Bool</c> (<c>pc:106749-106778</c>) defaults
+    /// an ABSENT attribute to false. Element <c>0x100000BF</c>'s resolved
+    /// attribute bag (the same fixture cited throughout this doc) carries NO
+    /// property "5" at all — unlike chat's channel menu (<c>0x10000014</c> in
+    /// LayoutDesc <c>0x21000006</c>), which explicitly authors property "5" =
+    /// <c>true</c>. So retail opens vendor's dropdown DOWNWARD and chat's
+    /// UPWARD — two different authored choices, not one hardcoded direction.
+    /// <see cref="UiMenu.OpenUpward"/> (default <c>true</c>, preserving
+    /// chat's untouched behavior) is set <c>false</c> here to match.
+    /// Retail's <c>Open</c> has no dynamic screen-edge clamp or flip of its
+    /// own — the direction is the fixed authored attribute, full stop — so
+    /// none is added here either; see <see cref="UiMenu.OpenUpward"/>'s own
+    /// doc for the citation.
+    /// </para>
+    /// <para>
+    /// <b>G8 (vendor gate finding, item 3 — popup/button text overflowing
+    /// instead of sitting flush left).</b> <see cref="UiMenu.TextIndent"/>
+    /// (19px) and <see cref="UiMenu.ButtonTextIndent"/> (20px) are CHAT's
+    /// own authored offsets — clearing space for a baked-in row checkbox and
+    /// a button-face LED socket, respectively. Vendor's row template
+    /// (<c>0x10000352</c>, live-dat verified <c>HJustify=Left</c>) has no
+    /// checkbox child at all, and vendor's button label child
+    /// (<c>0x1000034D</c>) is itself <c>HJustify=Left</c> at X=0 with no LED
+    /// art — so both indents are set to 0 here, retail's own left-justified
+    /// <c>UiText</c> convention for an icon-less label (every OTHER
+    /// dat-driven <c>UiText</c> in this codebase sets <c>Padding=0f</c>).
+    /// Reusing chat's 19px row indent measurably overflowed the authored
+    /// 100px-wide row: the longest category label, "Spell Components",
+    /// measures 92px at the default retail font (<c>Font 0x40000000</c>,
+    /// live-measured via <c>tools/VendorLayoutScan measure</c>) —
+    /// 19+92=111px &gt; the 100px row, an 11px overflow; with 0px it fits
+    /// with 8px to spare.
     /// </para>
     /// </summary>
     private const int TypeMenuRowsPerColumn = 6;
@@ -197,6 +247,10 @@ public sealed class VendorUiController : IRetainedPanelController
     private const uint TypeMenuItemHighlightSprite = 0x060012B4u;
     private const uint TypeMenuNormalSprite = 0x060012B3u;
     private const uint TypeMenuPressedSprite = 0x060012B4u;
+    // G6: the separate arrow-cap overlay (element 0x1000034E) — see the
+    // class doc's "G6" paragraph above.
+    private const uint TypeMenuArrowCapClosedSprite = 0x060012B1u;
+    private const uint TypeMenuArrowCapOpenSprite = 0x060012B2u;
 
     // G5 (vendor gate finding): the popup's docked scrollbar (element
     // 0x10000351, verified via tools/VendorLayoutScan against the live dat —
@@ -413,6 +467,22 @@ public sealed class VendorUiController : IRetainedPanelController
         _typeMenu.ScrollThumbBottomSprite = TypeMenuScrollThumbBottomSprite;
         _typeMenu.ScrollUpSprite = TypeMenuScrollUpSprite;
         _typeMenu.ScrollDownSprite = TypeMenuScrollDownSprite;
+        // G6: the separate open/closed arrow-cap overlay — see the class
+        // doc's "G6" paragraph above.
+        _typeMenu.ArrowCapClosedSprite = TypeMenuArrowCapClosedSprite;
+        _typeMenu.ArrowCapOpenSprite = TypeMenuArrowCapOpenSprite;
+        // G7: retail authors NO bool attribute 5 on this menu, so
+        // UIElement_Menu::Open's absent-defaults-false path opens the popup
+        // DOWNWARD (ScreenY1, the button's own bottom edge) — see the class
+        // doc's "G7" paragraph above. Chat's own menu is unaffected (its
+        // controller never touches this property, leaving UiMenu's true
+        // default).
+        _typeMenu.OpenUpward = false;
+        // G8: vendor's row/button-label children carry no checkbox/LED art
+        // to clear (unlike chat's), so both indents are flush-left (0) —
+        // see the class doc's "G8" paragraph above.
+        _typeMenu.TextIndent = 0f;
+        _typeMenu.ButtonTextIndent = 0f;
         _typeMenu.OnSelect = payload =>
         {
             if (payload is uint mask) SelectCategory(mask);