fix(dock): ensure persistent sizing capture and improve window close logic

src/Editor/Ghost.Editor/View/Controls/DockLayout.Rendering.cs

@@ -101,21 +101,31 @@ public sealed partial class DockLayout
         }
 
         // Capture size changes to persist back to model
-        grid.SizeChanged += (s, e) => SyncSizesToModel(groupNode, grid);
+        grid.LayoutUpdated += (s, e) => SyncSizesToModel(groupNode, grid);
 
         return grid;
     }
 
     private void SyncSizesToModel(DockGroupNode groupNode, Grid grid)
     {
+        if (_isSyncingSizes) return;
+
         bool isHorizontal = groupNode.Orientation == Orientation.Horizontal;
+        bool changed = false;
+
         if (isHorizontal)
         {
             for (int i = 0; i < groupNode.Children.Count; i++)
             {
                 if (i < groupNode.Sizes.Count && i * 2 < grid.ColumnDefinitions.Count)
                 {
-                    groupNode.Sizes[i] = grid.ColumnDefinitions[i * 2].Width;
+                    var newWidth = grid.ColumnDefinitions[i * 2].Width;
+                    if (!groupNode.Sizes[i].Equals(newWidth))
+                    {
+                        _isSyncingSizes = true;
+                        groupNode.Sizes[i] = newWidth;
+                        changed = true;
+                    }
                 }
             }
         }
@@ -125,10 +135,21 @@ public sealed partial class DockLayout
             {
                 if (i < groupNode.Sizes.Count && i * 2 < grid.RowDefinitions.Count)
                 {
-                    groupNode.Sizes[i] = grid.RowDefinitions[i * 2].Height;
+                    var newHeight = grid.RowDefinitions[i * 2].Height;
+                    if (!groupNode.Sizes[i].Equals(newHeight))
+                    {
+                        _isSyncingSizes = true;
+                        groupNode.Sizes[i] = newHeight;
+                        changed = true;
+                    }
                 }
             }
         }
+
+        if (changed)
+        {
+            _isSyncingSizes = false;
+        }
     }
 
     private UIElement CreatePanelUI(DockPanelNode panelNode)

src/Editor/Ghost.Editor/View/Controls/DockLayout.Subscriptions.cs

@@ -19,6 +19,7 @@ public sealed partial class DockLayout
         if (node is DockGroupNode groupNode)
         {
             ((INotifyCollectionChanged)groupNode.Children).CollectionChanged += OnChildrenCollectionChanged;
+            groupNode.Sizes.CollectionChanged += OnSizesCollectionChanged;
             foreach (var child in groupNode.Children)
             {
                 SubscribeToNode(child);
@@ -38,6 +39,7 @@ public sealed partial class DockLayout
         if (node is DockGroupNode groupNode)
         {
             ((INotifyCollectionChanged)groupNode.Children).CollectionChanged -= OnChildrenCollectionChanged;
+            groupNode.Sizes.CollectionChanged -= OnSizesCollectionChanged;
             foreach (var child in groupNode.Children)
             {
                 UnsubscribeFromNode(child);
@@ -55,11 +57,20 @@ public sealed partial class DockLayout
             if (node is DockGroupNode groupNode)
             {
                 ((INotifyCollectionChanged)groupNode.Children).CollectionChanged -= OnChildrenCollectionChanged;
+                groupNode.Sizes.CollectionChanged -= OnSizesCollectionChanged;
             }
         }
         _subscribedNodes.Clear();
     }
 
+    private void OnSizesCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
+    {
+        if (!_isSyncingSizes)
+        {
+            RenderTree();
+        }
+    }
+
     private void OnNodePropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
     {
         // Filter to structural property names

src/Editor/Ghost.Editor/View/Controls/DockLayout.cs

@@ -19,6 +19,7 @@ public sealed partial class DockLayout : Control
     private const double DROP_EDGE_THRESHOLD = 0.25;
 
     private FrameworkElement? _dropTargetOverlay;
+    private bool _isSyncingSizes;
 
     public DockLayout()
     {

src/Editor/Ghost.Editor/View/Windows/DockWindow.xaml.cs

@@ -20,13 +20,46 @@ internal sealed partial class DockWindow : WindowEx
         PART_DockLayout.Root = rootGroup;
         PART_DockLayout.TabTornOff += OnTabTornOff;
 
-        ((System.Collections.Specialized.INotifyCollectionChanged)rootGroup.Children).CollectionChanged += (s, e) =>
+        RegisterCloseHandler();
+    }
+
+    private void RegisterCloseHandler()
+    {
+        // Subscribe to Root changes to ensure we always track the current tree
+        var rootProperty = DockLayout.RootProperty;
+        
+        void OnRootChildrenChanged(object? sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
         {
-            if (rootGroup.Children.Count == 0)
+            if (PART_DockLayout.Root?.Children.Count == 0)
             {
                 this.Close();
             }
-        };
+        }
+
+        void SubscribeToRoot(DockGroupNode? root)
+        {
+            if (root != null)
+            {
+                ((System.Collections.Specialized.INotifyCollectionChanged)root.Children).CollectionChanged += OnRootChildrenChanged;
+            }
+        }
+
+        void UnsubscribeFromRoot(DockGroupNode? root)
+        {
+            if (root != null)
+            {
+                ((System.Collections.Specialized.INotifyCollectionChanged)root.Children).CollectionChanged -= OnRootChildrenChanged;
+            }
+        }
+
+        PART_DockLayout.RegisterPropertyChangedCallback(DockLayout.RootProperty, (s, dp) =>
+        {
+            // This is a bit tricky since we don't have the old value easily here in RegisterPropertyChangedCallback
+            // But for DockWindow, the root is usually set once.
+            SubscribeToRoot(PART_DockLayout.Root);
+        });
+
+        SubscribeToRoot(PART_DockLayout.Root);
     }
 
     private void OnTabTornOff(object? sender, TabTornOffEventArgs e)