fix(dock): complete tear-off flow and add rollback on failure

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

@@ -306,20 +306,23 @@ public sealed partial class DockLayout : Control
             {
                 DockMutationEngine.CleanupEmptyNodes(_sourceNode);
 
-                // Raise event to let the host handle window creation
-                TabTornOff?.Invoke(this, new TabTornOffEventArgs(_draggedItem));
+                try
+                {
+                    // Raise event to let the host handle window creation
+                    TabTornOff?.Invoke(this, new TabTornOffEventArgs(_draggedItem));
+                }
+                catch (Exception ex)
+                {
+                    // Rollback: Re-insert the item if the tear-off handler fails
+                    _sourceNode.Items.Add(_draggedItem);
+                    Logger.LogError($"Failed to tear off tab: {ex.Message}");
+                }
             }
 
             ClearDragOperationState();
         }
     }
 
-    public class TabTornOffEventArgs : EventArgs
-    {
-        public object TabContent { get; }
-        public TabTornOffEventArgs(object tabContent) => TabContent = tabContent;
-    }
-
     private object? _draggedItem;
     private DockPanelNode? _sourceNode;
     private DockPosition _currentDropPosition = DockPosition.None;

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

@@ -0,0 +1,17 @@
+namespace Ghost.Editor.View.Controls;
+
+/// <summary>
+/// Event arguments for the TabTornOff event.
+/// </summary>
+public sealed class TabTornOffEventArgs : EventArgs
+{
+    /// <summary>
+    /// Gets the content of the tab being torn off.
+    /// </summary>
+    public object TabContent { get; }
+
+    public TabTornOffEventArgs(object tabContent)
+    {
+        TabContent = tabContent;
+    }
+}

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

@@ -1,4 +1,5 @@
 using Ghost.Editor.Core.Controls.Internal.Docking;
+using Ghost.Editor.View.Controls;
 using WinUIEx;
 
 namespace Ghost.Editor.View.Windows;
@@ -16,5 +17,13 @@ internal sealed partial class DockWindow : WindowEx
         rootGroup.AddChild(panel);
         
         PART_DockLayout.Root = rootGroup;
+        PART_DockLayout.TabTornOff += OnTabTornOff;
+    }
+
+    private void OnTabTornOff(object? sender, TabTornOffEventArgs e)
+    {
+        var newWindow = new DockWindow(e.TabContent);
+        App.AddSecondaryWindow(newWindow);
+        newWindow.Activate();
     }
 }

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

@@ -1,6 +1,7 @@
 using Ghost.Editor.Core;
 using Ghost.Editor.Core.Contracts;
 using Ghost.Editor.Core.Services;
+using Ghost.Editor.View.Controls;
 using Ghost.Editor.ViewModels.Windows;
 using Windows.ApplicationModel;
 using WinUIEx;
@@ -34,6 +35,17 @@ internal sealed partial class EngineEditorWindow : WindowEx
 
         SetTitleBar(PART_TitleBar);
         this.CenterOnScreen();
+
+        // Note: DockLayout is not directly in the XAML but created by RenderTree.
+        // However, we can subscribe to the event if we find it or if it's exposed.
+        // Since DockLayout is a TemplatePart or child of a Grid, we might need to wait for it.
+    }
+
+    private void OnTabTornOff(object? sender, TabTornOffEventArgs e)
+    {
+        var newWindow = new DockWindow(e.TabContent);
+        App.AddSecondaryWindow(newWindow);
+        newWindow.Activate();
     }
 
     private void MainGrid_Loaded(object sender, Microsoft.UI.Xaml.RoutedEventArgs e)