feat(mission-control): make overview panes and queue strip individually resizable

Replace the UniformGrid (all tiles forced to equal size) with a real
Grid + GridSplitters built in code-behind per pane count/column count,
so panes resize individually. The queue strip's fixed 210px column
becomes a drag-resizable Grid column (min 160px) that collapses to 0
when nothing is queued, replacing the old dock-based fixed width.

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

@@ -51,10 +51,50 @@
       </Grid>
     </Border>
 
+    <!-- Body: main content | queue splitter | queue strip (widths managed in code-behind
+         so the queue column collapses to zero when nothing is queued). -->
+    <Grid x:Name="BodyGrid">
+      <Grid.ColumnDefinitions>
+        <ColumnDefinition Width="*"/>
+        <ColumnDefinition Width="Auto"/>
+        <ColumnDefinition Width="0"/>
+      </Grid.ColumnDefinitions>
+
+      <!-- Grid / tabs / empty state -->
+      <Panel Grid.Column="0" Margin="6">
+        <!-- Overview mode: a real Grid built in code-behind so each pane is individually
+             resizable via GridSplitters, instead of a UniformGrid where every cell is forced
+             to the same size. -->
+        <Grid x:Name="OverviewGrid" IsVisible="{Binding !IsFocusMode}" />
+
+        <!-- Focus mode: one pane large, switched via tabs -->
+        <TabControl ItemsSource="{Binding Panes}"
+                    SelectedItem="{Binding FocusedPane}"
+                    IsVisible="{Binding IsFocusMode}">
+          <TabControl.ItemTemplate>
+            <DataTemplate x:DataType="vmm:IMissionControlPane">
+              <TextBlock Text="{Binding DisplayTitle}" TextTrimming="CharacterEllipsis" MaxWidth="160" />
+            </DataTemplate>
+          </TabControl.ItemTemplate>
+        </TabControl>
+
+        <TextBlock IsVisible="{Binding !HasPanes}"
+                   Text="{loc:Tr missionControl.empty}"
+                   Foreground="{DynamicResource TextMuteBrush}"
+                   HorizontalAlignment="Center" VerticalAlignment="Center" />
+      </Panel>
+
+      <GridSplitter x:Name="QueueSplitter" Grid.Column="1"
+                    IsVisible="{Binding HasQueued}"
+                    Width="6"
+                    Background="Transparent"
+                    HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
+                    ResizeDirection="Columns"
+                    ResizeBehavior="PreviousAndNext"/>
+
       <!-- Read-only queue strip — collapses when nothing is queued -->
-    <Border DockPanel.Dock="Right"
+      <Border Grid.Column="2"
               IsVisible="{Binding HasQueued}"
-            Width="210"
               Background="{DynamicResource DeepBrush}"
               BorderBrush="{DynamicResource LineBrush}"
               BorderThickness="1,0,0,0">
@@ -102,34 +142,7 @@
           </ScrollViewer>
         </DockPanel>
       </Border>
-
+    </Grid>
-    <!-- Grid / tabs / empty state -->
-    <Panel Margin="6">
-      <!-- Overview mode: the existing UniformGrid, one tile per pane -->
-      <ItemsControl ItemsSource="{Binding Panes}" IsVisible="{Binding !IsFocusMode}">
-        <ItemsControl.ItemsPanel>
-          <ItemsPanelTemplate>
-            <UniformGrid x:CompileBindings="False" Columns="{Binding ColumnCount}" />
-          </ItemsPanelTemplate>
-        </ItemsControl.ItemsPanel>
-      </ItemsControl>
-
-      <!-- Focus mode: one pane large, switched via tabs -->
-      <TabControl ItemsSource="{Binding Panes}"
-                  SelectedItem="{Binding FocusedPane}"
-                  IsVisible="{Binding IsFocusMode}">
-        <TabControl.ItemTemplate>
-          <DataTemplate x:DataType="vmm:IMissionControlPane">
-            <TextBlock Text="{Binding DisplayTitle}" TextTrimming="CharacterEllipsis" MaxWidth="160" />
-          </DataTemplate>
-        </TabControl.ItemTemplate>
-      </TabControl>
-
-      <TextBlock IsVisible="{Binding !HasPanes}"
-                 Text="{loc:Tr missionControl.empty}"
-                 Foreground="{DynamicResource TextMuteBrush}"
-                 HorizontalAlignment="Center" VerticalAlignment="Center" />
-    </Panel>
 
   </DockPanel>
 </UserControl>

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

@@ -1,5 +1,10 @@
+using System;
+using System.Collections.Specialized;
+using System.ComponentModel;
 using Avalonia.Controls;
 using Avalonia.Interactivity;
+using Avalonia.Layout;
+using Avalonia.Media;
 using Avalonia.Platform.Storage;
 using ClaudeDo.Ui.ViewModels;
 
@@ -7,9 +12,20 @@ namespace ClaudeDo.Ui.Views.MissionControl;
 
 public partial class MissionControlView : UserControl
 {
+    private const double SplitterSize = 6;
+    private const double DefaultQueueWidth = 210;
+    private const double MinQueueWidth = 160;
+    private const double MinPaneWidth = 220;
+    private const double MinPaneHeight = 140;
+
+    private MissionControlViewModel? _vm;
+    private GridLength _queueWidth = new(DefaultQueueWidth, GridUnitType.Pixel);
+
     public MissionControlView()
     {
         InitializeComponent();
+        DataContextChanged += OnDataContextChanged;
+        QueueSplitter.DragCompleted += (_, _) => _queueWidth = BodyGrid.ColumnDefinitions[2].Width;
     }
 
     // Ad-hoc ConPTY session: the view owns the folder picker, the VM only takes the chosen path.
@@ -28,4 +44,127 @@ public partial class MissionControlView : UserControl
 
         await vm.OpenAdHocConPtySessionAsync(folders[0].Path.LocalPath);
     }
+
+    private void OnDataContextChanged(object? sender, EventArgs e)
+    {
+        if (_vm is not null)
+        {
+            _vm.Panes.CollectionChanged -= OnPanesChanged;
+            _vm.PropertyChanged -= OnViewModelPropertyChanged;
+        }
+
+        _vm = DataContext as MissionControlViewModel;
+
+        if (_vm is not null)
+        {
+            _vm.Panes.CollectionChanged += OnPanesChanged;
+            _vm.PropertyChanged += OnViewModelPropertyChanged;
+        }
+
+        RebuildOverviewGrid();
+        UpdateQueueColumn();
+    }
+
+    private void OnPanesChanged(object? sender, NotifyCollectionChangedEventArgs e) => RebuildOverviewGrid();
+
+    private void OnViewModelPropertyChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName == nameof(MissionControlViewModel.ColumnCount))
+            RebuildOverviewGrid();
+        else if (e.PropertyName == nameof(MissionControlViewModel.HasQueued))
+            UpdateQueueColumn();
+    }
+
+    // The queue column is Pixel-widthed (so the splitter can drag it) — when nothing is
+    // queued it collapses to 0 instead of leaving a blank gap, and remembers the last
+    // dragged width for the rest of this window's lifetime (not persisted beyond it).
+    private void UpdateQueueColumn()
+    {
+        var queueColumn = BodyGrid.ColumnDefinitions[2];
+        if (_vm?.HasQueued == true)
+        {
+            queueColumn.MinWidth = MinQueueWidth;
+            queueColumn.Width = _queueWidth;
+        }
+        else
+        {
+            queueColumn.MinWidth = 0;
+            queueColumn.Width = new GridLength(0, GridUnitType.Pixel);
+        }
+    }
+
+    // Replaces the old UniformGrid with a real Grid + GridSplitters so panes resize
+    // individually. Column splitters span every row (resize that whole column vs. its
+    // neighbor); row splitters span every column. Rebuilt from scratch whenever the pane
+    // count or column count changes — per-pane sizes are intentionally not preserved across
+    // a rebuild (session-only resizing, reset to the default split when panes come/go).
+    private void RebuildOverviewGrid()
+    {
+        OverviewGrid.Children.Clear();
+        OverviewGrid.ColumnDefinitions.Clear();
+        OverviewGrid.RowDefinitions.Clear();
+
+        var panes = _vm?.Panes;
+        if (panes is not { Count: > 0 }) return;
+
+        var columns = Math.Max(1, _vm!.ColumnCount);
+        var rows = (int)Math.Ceiling(panes.Count / (double)columns);
+
+        for (var c = 0; c < columns; c++)
+        {
+            if (c > 0) OverviewGrid.ColumnDefinitions.Add(new ColumnDefinition(GridLength.Auto));
+            OverviewGrid.ColumnDefinitions.Add(new ColumnDefinition(new GridLength(1, GridUnitType.Star)) { MinWidth = MinPaneWidth });
+        }
+
+        for (var r = 0; r < rows; r++)
+        {
+            if (r > 0) OverviewGrid.RowDefinitions.Add(new RowDefinition(GridLength.Auto));
+            OverviewGrid.RowDefinitions.Add(new RowDefinition(new GridLength(1, GridUnitType.Star)) { MinHeight = MinPaneHeight });
+        }
+
+        var totalGridRows = rows * 2 - 1;
+        var totalGridCols = columns * 2 - 1;
+
+        for (var c = 1; c < columns; c++)
+        {
+            var splitter = new GridSplitter
+            {
+                Width = SplitterSize,
+                Background = Brushes.Transparent,
+                HorizontalAlignment = HorizontalAlignment.Stretch,
+                VerticalAlignment = VerticalAlignment.Stretch,
+                ResizeDirection = GridResizeDirection.Columns,
+                ResizeBehavior = GridResizeBehavior.PreviousAndNext,
+            };
+            Grid.SetColumn(splitter, c * 2 - 1);
+            Grid.SetRow(splitter, 0);
+            Grid.SetRowSpan(splitter, totalGridRows);
+            OverviewGrid.Children.Add(splitter);
+        }
+
+        for (var r = 1; r < rows; r++)
+        {
+            var splitter = new GridSplitter
+            {
+                Height = SplitterSize,
+                Background = Brushes.Transparent,
+                HorizontalAlignment = HorizontalAlignment.Stretch,
+                VerticalAlignment = VerticalAlignment.Stretch,
+                ResizeDirection = GridResizeDirection.Rows,
+                ResizeBehavior = GridResizeBehavior.PreviousAndNext,
+            };
+            Grid.SetColumn(splitter, 0);
+            Grid.SetColumnSpan(splitter, totalGridCols);
+            Grid.SetRow(splitter, r * 2 - 1);
+            OverviewGrid.Children.Add(splitter);
+        }
+
+        for (var i = 0; i < panes.Count; i++)
+        {
+            var presenter = new ContentControl { Content = panes[i] };
+            Grid.SetColumn(presenter, (i % columns) * 2);
+            Grid.SetRow(presenter, (i / columns) * 2);
+            OverviewGrid.Children.Add(presenter);
+        }
+    }
 }