fix(diff): resolve themed brushes and stop recomputing alignment on layout toggle

src/ClaudeDo.Ui/Views/Controls/DiffTextView.axaml.cs

@@ -76,23 +76,34 @@ public partial class DiffTextView : UserControl
         _leftTm = LeftEditor.InstallTextMate(Registry);
         _rightTm = RightEditor.InstallTextMate(Registry);
         InstallRenderers();
-        Rebuild();
+        ReloadFile();
         HookScrollSync();
     }
 
     protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
     {
         base.OnPropertyChanged(change);
-        if (change.Property == FileProperty || change.Property == IsSplitProperty)
+        if (change.Property == FileProperty)
-            Rebuild();
+            ReloadFile();
+        else if (change.Property == IsSplitProperty)
+            RefreshLayout();
         else if (change.Property == WrapLinesProperty)
             ApplyWrap();
     }
 
-    private void Rebuild()
+    /// Recomputes the alignment (word-diff LCS) for the current <see cref="File"/> and then
+    /// refreshes everything downstream of it. Only ever needed when the file actually changes.
+    private void ReloadFile()
     {
         _aligned = DiffAlignment.Build(File?.Lines);
+        RefreshLayout();
+    }
 
+    /// Re-applies the current <see cref="_aligned"/> to the editors for the current layout
+    /// (split vs unified). A single <see cref="AlignedDiff"/> already carries both row sets,
+    /// so toggling <see cref="IsSplit"/> never needs to re-run the alignment.
+    private void RefreshLayout()
+    {
         var split = IsSplit;
         RightEditor.IsVisible = split;
         PaneDivider.IsVisible = split;
@@ -181,7 +192,7 @@ public partial class DiffTextView : UserControl
     }
 
     private IBrush Brush(string key, Color fallback) =>
-        this.TryGetResource(key, ActualThemeVariant, out var value) && value is IBrush brush
+        this.TryFindResource(key, out var value) && value is IBrush brush
             ? brush
             : new SolidColorBrush(fallback);
 
@@ -235,11 +246,20 @@ public partial class DiffTextView : UserControl
             if (WrapLines)
             {
                 // Line heights differ once lines wrap, so anchor on the top visible line.
+                // ScrollToLine/ScrollTo are "bring into view" primitives (they park the line
+                // near mid-viewport past a hysteresis threshold) — top-align by computing the
+                // target's own vertical offset for that document line and assigning it
+                // directly, the same way the non-wrap branch assigns Offset below. That is
+                // synchronous, so the same offset-comparison guard makes the echo self-terminate.
                 var topLine = sourceEditor.TextArea.TextView.VisualLines is { Count: > 0 } visualLines
                     ? visualLines[0].FirstDocumentLine.LineNumber
                     : (int?)null;
                 if (topLine is { } line && line >= 1 && line <= targetEditor.Document.LineCount)
-                    targetEditor.ScrollToLine(line);
+                {
+                    var targetTop = targetEditor.TextArea.TextView.GetVisualTopByDocumentLine(line);
+                    if (Math.Abs(target.Offset.Y - targetTop) > 0.5)
+                        target.Offset = new Vector(target.Offset.X, targetTop);
+                }
             }
             else if (Math.Abs(target.Offset.Y - source.Offset.Y) > 0.5)
             {