M162: Add frontend docking infrastructure

Quantum.Editor.Avalonia/App.axaml

@@ -2,8 +2,10 @@
     x:Class="Quantum.Editor.Avalonia.App"
     xmlns="https://github.com/avaloniaui"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:dockTheme="using:Dock.Avalonia.Themes.Fluent"
     RequestedThemeVariant="Dark">
     <Application.Styles>
         <FluentTheme />
+        <dockTheme:DockFluentTheme DensityStyle="Compact" />
     </Application.Styles>
 </Application>

Quantum.Editor.Avalonia/MainWindow.axaml

@@ -2,7 +2,7 @@
     x:Class="Quantum.Editor.Avalonia.MainWindow"
     xmlns="https://github.com/avaloniaui"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-    xmlns:controls="using:Quantum.Editor.Avalonia.Controls"
+    xmlns:dock="using:Dock.Avalonia.Controls"
     Title="Quantum CoasterWorks Editor"
     Width="1480"
     Height="920"
@@ -42,7 +42,7 @@
         </Style>
     </Window.Styles>
 
-    <Grid x:Name="WorkbenchGrid" RowDefinitions="Auto,48,*,5,300,28">
+    <Grid x:Name="WorkbenchGrid" RowDefinitions="Auto,48,*,28">
         <Border
             x:Name="MenuBarRegion"
             Grid.Row="0"
@@ -67,6 +67,14 @@
                     <MenuItem Header="_Fit Track    F" Click="OnFitViewportClick" />
                     <MenuItem Header="Toggle Transported _Frames" Click="OnMenuShowFramesClick" />
                     <MenuItem Header="Math _Plots" Click="OnShowEngineeringPlotsClick" />
+                    <Separator />
+                    <MenuItem Header="_Panes">
+                        <MenuItem Header="_Route" Tag="route" Click="OnShowPaneClick" />
+                        <MenuItem Header="_Viewport" Tag="viewport" Click="OnShowPaneClick" />
+                        <MenuItem Header="_Inspector" Tag="inspector" Click="OnShowPaneClick" />
+                        <MenuItem Header="_Math Plots" Tag="math-plots" Click="OnShowPaneClick" />
+                        <MenuItem Header="_Diagnostics" Tag="diagnostics" Click="OnShowPaneClick" />
+                    </MenuItem>
                 </MenuItem>
             </Menu>
         </Border>
@@ -106,50 +114,15 @@
             </Grid>
         </Border>
 
-        <Grid x:Name="ContentPaneGrid" Grid.Row="2" ColumnDefinitions="320,5,*,5,340">
-            <controls:RoutePaneControl
-                x:Name="RoutePane"
-                Grid.Column="0"
-                NodeSelected="OnGraphNodeSelected"
-                SectionPointerChanged="OnSectionPointerChanged" />
-
-            <GridSplitter x:Name="RouteSplitter" Grid.Column="1" ResizeDirection="Columns" Background="#2B3948" />
-
-            <controls:ViewportPaneControl
-                x:Name="ViewportPane"
-                Grid.Column="2"
-                SectionPointerChanged="OnSectionPointerChanged"
-                SampleSelected="OnViewportSampleSelected" />
-
-            <GridSplitter x:Name="InspectorSplitter" Grid.Column="3" ResizeDirection="Columns" Background="#2B3948" />
-
-            <controls:InspectorPaneControl x:Name="InspectorPane" Grid.Column="4" />
-        </Grid>
-
-        <GridSplitter x:Name="BottomPanelSplitter" Grid.Row="3" ResizeDirection="Rows" Background="#2B3948" />
-
-        <Border
-            x:Name="BottomPanelRegion"
-            Grid.Row="4"
-            Classes="panel"
-            BorderThickness="0,1,0,0">
-            <TabControl x:Name="BottomWorkspaceTabs" SelectedIndex="0">
-                <TabItem x:Name="MathPlotsTab" Header="MATH PLOTS">
-                    <controls:MathPlotsPaneControl
-                        x:Name="MathPlotsPane"
-                        SectionPointerChanged="OnSectionPointerChanged"
-                        StationChanged="OnEngineeringPlotStationChanged"
-                        StationSelected="OnEngineeringPlotStationSelected" />
-                </TabItem>
-                <TabItem x:Name="DiagnosticsTab" Header="DIAGNOSTICS">
-                    <controls:DiagnosticsPaneControl x:Name="DiagnosticsPane" />
-                </TabItem>
-            </TabControl>
-        </Border>
+        <dock:DockControl
+            x:Name="DockHost"
+            Grid.Row="2"
+            InitializeFactory="False"
+            InitializeLayout="False" />
 
         <Border
             x:Name="StatusBarRegion"
-            Grid.Row="5"
+            Grid.Row="3"
             Background="#0B1016"
             BorderBrush="#2B3948"
             BorderThickness="0,1,0,0"

Quantum.Editor.Avalonia/MainWindow.axaml.cs

@@ -8,6 +8,7 @@
 using Quantum.Editor.Avalonia.Models;
 using Quantum.Editor.Avalonia.Services;
 using Quantum.Editor.Avalonia.Services.Commands;
+using Quantum.Editor.Avalonia.Services.Docking;
 using Quantum.Editor.Avalonia.Services.Documents;
 using Quantum.Editor.Avalonia.Services.Workspaces;
 
@@ -23,6 +24,12 @@ public partial class MainWindow : Window
 
     private readonly EditorWorkspace workspace;
     private readonly WorkspaceProfileManager workspaceProfiles;
+    private readonly EditorDockingAdapter docking;
+    private readonly RoutePaneControl RoutePane;
+    private readonly ViewportPaneControl ViewportPane;
+    private readonly InspectorPaneControl InspectorPane;
+    private readonly MathPlotsPaneControl MathPlotsPane;
+    private readonly DiagnosticsPaneControl DiagnosticsPane;
 
     public MainWindow()
         : this(CreateWorkspace(), new WorkspaceProfileManager())
@@ -43,6 +50,27 @@ public MainWindow(
             throw new ArgumentNullException(nameof(workspaceProfiles));
         InitializeComponent();
 
+        RoutePane = new RoutePaneControl();
+        ViewportPane = new ViewportPaneControl();
+        InspectorPane = new InspectorPaneControl();
+        MathPlotsPane = new MathPlotsPaneControl();
+        DiagnosticsPane = new DiagnosticsPaneControl();
+        WirePaneInteractions();
+
+        DockPaneRegistry paneRegistry = DockPaneRegistry.CreateDefaultTrack();
+        docking = new EditorDockingAdapter(
+            paneRegistry,
+            new Dictionary<string, object>(StringComparer.Ordinal)
+            {
+                [WorkspacePaneIds.Route] = RoutePane,
+                [WorkspacePaneIds.Viewport] = ViewportPane,
+                [WorkspacePaneIds.Inspector] = InspectorPane,
+                [WorkspacePaneIds.MathPlots] = MathPlotsPane,
+                [WorkspacePaneIds.Diagnostics] = DiagnosticsPane
+            });
+        DockHost.Factory = docking.Factory;
+        DockHost.Layout = docking.Layout;
+
         this.workspace.WorkspaceChanged += OnWorkspaceChanged;
         this.workspace.StationCursorChanged += OnStationCursorChanged;
         this.workspace.SectionHighlightChanged += OnSectionHighlightChanged;
@@ -57,13 +85,26 @@ public MainWindow(
 
     public WorkspaceProfileManager WorkspaceProfiles => workspaceProfiles;
 
+    public EditorDockingAdapter Docking => docking;
+
     private static EditorWorkspace CreateWorkspace()
     {
         var result = new EditorWorkspace();
         result.NewDocument();
         return result;
     }
 
+    private void WirePaneInteractions()
+    {
+        RoutePane.NodeSelected += OnGraphNodeSelected;
+        RoutePane.SectionPointerChanged += OnSectionPointerChanged;
+        ViewportPane.SectionPointerChanged += OnSectionPointerChanged;
+        ViewportPane.SampleSelected += OnViewportSampleSelected;
+        MathPlotsPane.SectionPointerChanged += OnSectionPointerChanged;
+        MathPlotsPane.StationChanged += OnEngineeringPlotStationChanged;
+        MathPlotsPane.StationSelected += OnEngineeringPlotStationSelected;
+    }
+
     private void OnWorkspaceChanged(object? sender, EventArgs eventArgs)
     {
         UpdateWorkspaceView();
@@ -77,38 +118,21 @@ private void OnCurrentProfileChanged(object? sender, EventArgs eventArgs)
 
     private void ApplyWorkspaceProfile(WorkspaceProfile profile)
     {
-        bool showRoute = profile.IsPaneVisibleByDefault(WorkspacePaneIds.Route);
-        bool showViewport = profile.IsPaneVisibleByDefault(WorkspacePaneIds.Viewport);
-        bool showInspector = profile.IsPaneVisibleByDefault(WorkspacePaneIds.Inspector);
-        bool showMathPlots = profile.IsPaneVisibleByDefault(WorkspacePaneIds.MathPlots);
-        bool showDiagnostics = profile.IsPaneVisibleByDefault(WorkspacePaneIds.Diagnostics);
-        bool showBottomPanel = showMathPlots || showDiagnostics;
-
-        RoutePane.IsVisible = showRoute;
-        ViewportPane.IsVisible = showViewport;
-        InspectorPane.IsVisible = showInspector;
-        RouteSplitter.IsVisible = showRoute && showViewport;
-        InspectorSplitter.IsVisible = showViewport && showInspector;
-        MathPlotsTab.IsVisible = showMathPlots;
-        DiagnosticsTab.IsVisible = showDiagnostics;
-        BottomPanelRegion.IsVisible = showBottomPanel;
-        BottomPanelSplitter.IsVisible = showBottomPanel;
-        if (showBottomPanel &&
-            BottomWorkspaceTabs.SelectedItem is Control selectedTab &&
-            !selectedTab.IsVisible)
-        {
-            BottomWorkspaceTabs.SelectedItem = showMathPlots ? MathPlotsTab : DiagnosticsTab;
-        }
-
-        ContentPaneGrid.ColumnDefinitions[0].Width = new GridLength(showRoute ? 320 : 0);
-        ContentPaneGrid.ColumnDefinitions[1].Width = new GridLength(showRoute && showViewport ? 5 : 0);
-        ContentPaneGrid.ColumnDefinitions[2].Width = showViewport
-            ? new GridLength(1, GridUnitType.Star)
-            : new GridLength(0);
-        ContentPaneGrid.ColumnDefinitions[3].Width = new GridLength(showViewport && showInspector ? 5 : 0);
-        ContentPaneGrid.ColumnDefinitions[4].Width = new GridLength(showInspector ? 340 : 0);
-        WorkbenchGrid.RowDefinitions[3].Height = new GridLength(showBottomPanel ? 5 : 0);
-        WorkbenchGrid.RowDefinitions[4].Height = new GridLength(showBottomPanel ? 300 : 0);
+        docking.SetPaneVisible(
+            WorkspacePaneIds.Route,
+            profile.IsPaneVisibleByDefault(WorkspacePaneIds.Route));
+        docking.SetPaneVisible(
+            WorkspacePaneIds.Viewport,
+            profile.IsPaneVisibleByDefault(WorkspacePaneIds.Viewport));
+        docking.SetPaneVisible(
+            WorkspacePaneIds.Inspector,
+            profile.IsPaneVisibleByDefault(WorkspacePaneIds.Inspector));
+        docking.SetPaneVisible(
+            WorkspacePaneIds.MathPlots,
+            profile.IsPaneVisibleByDefault(WorkspacePaneIds.MathPlots));
+        docking.SetPaneVisible(
+            WorkspacePaneIds.Diagnostics,
+            profile.IsPaneVisibleByDefault(WorkspacePaneIds.Diagnostics));
 
         bool showFileCommands = profile.HasCommandGroup(WorkspaceCommandGroupIds.File);
         bool showEditCommands = profile.HasCommandGroup(WorkspaceCommandGroupIds.Edit);
@@ -361,7 +385,15 @@ private void OnMenuShowFramesClick(object? sender, RoutedEventArgs eventArgs)
 
     private void OnShowEngineeringPlotsClick(object? sender, RoutedEventArgs eventArgs)
     {
-        BottomWorkspaceTabs.SelectedIndex = 0;
+        docking.ShowPane(WorkspacePaneIds.MathPlots);
+    }
+
+    private void OnShowPaneClick(object? sender, RoutedEventArgs eventArgs)
+    {
+        if (sender is MenuItem { Tag: string paneId })
+        {
+            docking.ShowPane(paneId);
+        }
     }
 
     private void OnEngineeringPlotStationChanged(

Quantum.Editor.Avalonia/Quantum.Editor.Avalonia.csproj

@@ -12,6 +12,9 @@
     <PackageReference Include="Avalonia" Version="12.0.5" />
     <PackageReference Include="Avalonia.Desktop" Version="12.0.5" />
     <PackageReference Include="Avalonia.Themes.Fluent" Version="12.0.5" />
+    <PackageReference Include="Dock.Avalonia" Version="12.0.0.2" />
+    <PackageReference Include="Dock.Avalonia.Themes.Fluent" Version="12.0.0.2" />
+    <PackageReference Include="Dock.Model.Mvvm" Version="12.0.0.2" />
   </ItemGroup>
 
   <ItemGroup>

Quantum.Editor.Avalonia/Services/Docking/DockPaneRegistration.cs

@@ -0,0 +1,30 @@
+namespace Quantum.Editor.Avalonia.Services.Docking;
+
+/// <summary>
+/// Frontend-only metadata for one dockable editor pane.
+/// </summary>
+public sealed class DockPaneRegistration
+{
+    public DockPaneRegistration(string id, string title, bool canClose = true)
+    {
+        if (string.IsNullOrWhiteSpace(id))
+        {
+            throw new ArgumentException("A dock pane identifier cannot be empty.", nameof(id));
+        }
+
+        if (string.IsNullOrWhiteSpace(title))
+        {
+            throw new ArgumentException("A dock pane title cannot be empty.", nameof(title));
+        }
+
+        Id = id.Trim();
+        Title = title.Trim();
+        CanClose = canClose;
+    }
+
+    public string Id { get; }
+
+    public string Title { get; }
+
+    public bool CanClose { get; }
+}

Quantum.Editor.Avalonia/Services/Docking/DockPaneRegistry.cs

@@ -0,0 +1,57 @@
+using Quantum.Editor.Avalonia.Services.Workspaces;
+
+namespace Quantum.Editor.Avalonia.Services.Docking;
+
+/// <summary>
+/// Registers the panes understood by the Avalonia docking composition root.
+/// </summary>
+public sealed class DockPaneRegistry
+{
+    private readonly Dictionary<string, DockPaneRegistration> panesById =
+        new(StringComparer.Ordinal);
+    private readonly List<DockPaneRegistration> panes = new();
+
+    public IReadOnlyList<DockPaneRegistration> Panes => panes.AsReadOnly();
+
+    public static DockPaneRegistry CreateDefaultTrack()
+    {
+        var result = new DockPaneRegistry();
+        result.Register(new DockPaneRegistration(WorkspacePaneIds.Route, "Route"));
+        result.Register(new DockPaneRegistration(
+            WorkspacePaneIds.Viewport,
+            "Viewport",
+            canClose: false));
+        result.Register(new DockPaneRegistration(WorkspacePaneIds.Inspector, "Inspector"));
+        result.Register(new DockPaneRegistration(WorkspacePaneIds.MathPlots, "Math Plots"));
+        result.Register(new DockPaneRegistration(WorkspacePaneIds.Diagnostics, "Diagnostics"));
+        return result;
+    }
+
+    public void Register(DockPaneRegistration pane)
+    {
+        ArgumentNullException.ThrowIfNull(pane);
+        if (panesById.ContainsKey(pane.Id))
+        {
+            throw new InvalidOperationException($"Dock pane '{pane.Id}' is already registered.");
+        }
+
+        panesById.Add(pane.Id, pane);
+        panes.Add(pane);
+    }
+
+    public bool Contains(string paneId) =>
+        !string.IsNullOrWhiteSpace(paneId) && panesById.ContainsKey(paneId);
+
+    public bool TryGet(string paneId, out DockPaneRegistration pane) =>
+        panesById.TryGetValue(paneId, out pane!);
+
+    public DockPaneRegistration Get(string paneId)
+    {
+        if (!panesById.TryGetValue(paneId, out DockPaneRegistration? pane))
+        {
+            throw new KeyNotFoundException($"Dock pane '{paneId}' is not registered.");
+        }
+
+        return pane;
+    }
+}

Quantum.Editor.Avalonia/Services/Docking/DockingLayoutIds.cs

@@ -0,0 +1,15 @@
+namespace Quantum.Editor.Avalonia.Services.Docking;
+
+/// <summary>
+/// Stable identifiers for the frontend-only default docking graph.
+/// </summary>
+public static class DockingLayoutIds
+{
+    public const string Root = "track-root";
+    public const string Main = "track-main";
+    public const string Top = "track-top";
+    public const string RouteHost = "track-route-host";
+    public const string ViewportHost = "track-viewport-host";
+    public const string InspectorHost = "track-inspector-host";
+    public const string BottomHost = "track-bottom-host";
+}