fix(ui): preserve cropped chat and button faces

src/AcDream.App/UI/UiElement.cs

@@ -483,11 +483,41 @@ public abstract class UiElement
         Left = x; Top = y; Width = w; Height = h;
     }
 
-    /// <summary>Forget the captured anchor margins so the next <see cref="ApplyAnchor"/>
-    /// re-captures them from the CURRENT rect. Call after manually repositioning/resizing
-    /// an anchored element at runtime (e.g. reflowing the chat input when the channel
-    /// button width changes) so the new rect becomes the anchor baseline.</summary>
-    internal void ResetAnchorCapture() => _anchorCaptured = false;
+    /// <summary>
+    /// Make the current geometry the new layout baseline after an intentional
+    /// controller/runtime change. Compatibility anchors recapture their margins on
+    /// the next layout pass; imported raw-edge policies rebase immediately against
+    /// the current parent rect.
+    /// </summary>
+    internal void ResetAnchorCapture()
+    {
+        _anchorCaptured = false;
+        if (LayoutPolicy is null || Parent is null) return;
+
+        LayoutPolicy.Rebase(
+            UiPixelRect.FromPositionAndSize(
+                (int)Left,
+                (int)Top,
+                (int)Width,
+                (int)Height),
+            UiPixelRect.FromPositionAndSize(
+                0,
+                0,
+                (int)Parent.Width,
+                (int)Parent.Height));
+    }
+
+    /// <summary>
+    /// Rebase each immediate child after a host deliberately changes this element's
+    /// design extent. This is used when a production DAT root contains auxiliary
+    /// space that is cropped by its retail window mount; descendants must reflow
+    /// from the mounted content rect, not from the uncropped LayoutDesc display box.
+    /// </summary>
+    internal void RebaseChildLayoutBaselines()
+    {
+        foreach (var child in _children)
+            child.ResetAnchorCapture();
+    }
 
     /// <summary>Walk up to the owning <see cref="UiRoot"/> (the top of the tree), or null
     /// if this element is not attached. Lets a widget reach focus/capture services — e.g.