feat(ui): drag-reorder Mission Control panes by their header

src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml.cs

@@ -1,8 +1,46 @@
+using System.Linq;
 using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Avalonia.VisualTree;
+using ClaudeDo.Ui.ViewModels;
+using ClaudeDo.Ui.ViewModels.Islands;
 
 namespace ClaudeDo.Ui.Views.MissionControl;
 
 public partial class MissionControlView : UserControl
 {
-    public MissionControlView() => InitializeComponent();
+    // Shared with MonitorPaneView (the drag source).
+    public static readonly DataFormat<string> PaneFormat =
+        DataFormat.CreateStringApplicationFormat("claudedo-monitor-pane");
+
+    public MissionControlView()
+    {
+        InitializeComponent();
+        AddHandler(DragDrop.DragOverEvent, OnPaneDragOver);
+        AddHandler(DragDrop.DropEvent, OnPaneDrop);
+    }
+
+    private void OnPaneDragOver(object? sender, DragEventArgs e)
+    {
+        e.DragEffects = (e.DataTransfer?.Contains(PaneFormat) ?? false)
+            ? DragDropEffects.Move
+            : DragDropEffects.None;
+    }
+
+    private void OnPaneDrop(object? sender, DragEventArgs e)
+    {
+        if (DataContext is not MissionControlViewModel vm) return;
+        var draggedId = e.DataTransfer?.TryGetValue(PaneFormat);
+        if (string.IsNullOrEmpty(draggedId)) return;
+        if (e.Source is not Avalonia.Visual src) return;
+
+        var targetPane = src.FindAncestorOfType<MonitorPaneView>();
+        if (targetPane?.DataContext is not TaskMonitorViewModel target) return;
+
+        var dragged = vm.Monitors.FirstOrDefault(m => m.SubscribedTaskId == draggedId);
+        if (dragged is null) return;
+
+        vm.MoveMonitor(dragged, target);
+    }
 }

src/ClaudeDo.Ui/Views/MissionControl/MonitorPaneView.axaml

@@ -6,6 +6,7 @@
              x:DataType="vm:TaskMonitorViewModel"
              x:Class="ClaudeDo.Ui.Views.MissionControl.MonitorPaneView">
   <Border Classes="monitor-pane"
+          DragDrop.AllowDrop="True"
           Classes.mon-review="{Binding IsWaitingForReview}"
           Classes.mon-done="{Binding IsDone}"
           Classes.mon-roadblock="{Binding HasRoadblock}"
@@ -17,7 +18,8 @@
       <Border DockPanel.Dock="Top"
               Background="{DynamicResource Surface2Brush}"
               BorderBrush="{DynamicResource LineBrush}"
-              BorderThickness="0,0,0,1" Padding="6,3">
+              BorderThickness="0,0,0,1" Padding="6,3"
+              PointerPressed="OnHeaderPressed">
         <StackPanel Orientation="Horizontal" Spacing="2"
                     HorizontalAlignment="Right" VerticalAlignment="Center">
           <Button Classes="title-ctrl"

src/ClaudeDo.Ui/Views/MissionControl/MonitorPaneView.axaml.cs

@@ -1,8 +1,26 @@
 using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.VisualTree;
+using ClaudeDo.Ui.ViewModels.Islands;
 
 namespace ClaudeDo.Ui.Views.MissionControl;
 
 public partial class MonitorPaneView : UserControl
 {
     public MonitorPaneView() => InitializeComponent();
+
+    private async void OnHeaderPressed(object? sender, PointerPressedEventArgs e)
+    {
+        if (DataContext is not TaskMonitorViewModel m || m.SubscribedTaskId is not { } id) return;
+        if (e.Source is not Avalonia.Visual src) return;
+        if (!e.GetCurrentPoint(this).Properties.IsLeftButtonPressed) return;
+
+        // Don't start a drag when the press landed on a header action button.
+        var button = src as Button ?? src.FindAncestorOfType<Button>();
+        if (button is not null) return;
+
+        var data = new DataTransfer();
+        data.Add(DataTransferItem.Create(MissionControlView.PaneFormat, id));
+        await DragDrop.DoDragDropAsync(e, data, DragDropEffects.Move);
+    }
 }