fix(ui): bind visible skills scrollbar

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

@@ -621,8 +621,13 @@ public static class CharacterStatController
         if (spriteResolve is null)
             return null;
 
-        UiElement? source =
+        // The mounted character sublayout contains duplicated stat-management
-            (contentPage is not null
+        // branches with the same element ids. Bind the scrollbar adjacent to the
+        // active list first; a page-wide DFS can select an inactive duplicate that
+        // is never drawn while leaving the visible gutter unconfigured.
+        UiElement? source = statList?.Parent?.Children.FirstOrDefault(
+                static el => HasDatElementId(el, ListScrollbarId))
+            ?? (contentPage is not null
                 ? FindInSubtree(contentPage, static el => HasDatElementId(el, ListScrollbarId))
                 : null)
             ?? layout.FindElement(ListScrollbarId);
@@ -1674,7 +1679,17 @@ public static class CharacterStatController
         => DatElementId(element) == id;
 
     private static uint DatElementId(UiElement element)
-        => element switch
+    {
+        // DatWidgetFactory assigns the canonical id on every imported widget,
+        // including behavioral types such as UiScrollbar that do not expose a
+        // type-specific ElementId property. Prefer it so subtree role lookup is
+        // independent of the concrete widget class. The fallbacks keep the small
+        // hand-built controller fixtures working when they construct widgets
+        // directly instead of through the factory.
+        if (element.DatElementId != 0u)
+            return element.DatElementId;
+
+        return element switch
         {
             UiDatElement datElement => datElement.ElementId,
             UiButton button => button.ElementId,
@@ -1682,6 +1697,7 @@ public static class CharacterStatController
             UiText text => text.ElementId,
             _ => 0u,
         };
+    }
 
     private static UiElement? FindElementByDatId(ImportedLayout layout, UiElement? scope, uint id)
     {

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

@@ -1501,9 +1501,18 @@ public class CharacterStatControllerTests
         Assert.Equal((510f, 7f), (divider.Top, divider.Height));
         Assert.Equal(3, footers.Count);
         Assert.All(footers, footer => Assert.Equal((520f, 55f), (footer.Top, footer.Height)));
+        Assert.False(
+            scrollbar.Visible,
+            $"pre-skills scrollbar: model={scrollbar.Model is not null}, " +
+            $"resolve={scrollbar.SpriteResolve is not null}, track=0x{scrollbar.TrackSprite:X8}");
 
         ClickTab(layout, left: 92f);
         Assert.True(scrollbar.Visible);
+        Assert.NotNull(scrollbar.Model);
+        Assert.NotNull(scrollbar.SpriteResolve);
+        Assert.Equal(0x06004C5Fu, scrollbar.TrackSprite);
+        Assert.Equal(0x06004C6Cu, scrollbar.UpSprite);
+        Assert.Equal(0x06004C69u, scrollbar.DownSprite);
     }
 
     // ── Helpers ──────────────────────────────────────────────────────────────