feat.动画优化与更新界面

.trae/specs/main-window-desktop-layer/design.md

@@ -0,0 +1,42 @@
+# Main Window Desktop Layer Design
+
+## Window Roles
+
+Lan Mountain Desktop now has three separate window-layer roles:
+
+- `MainDesktopWindow`: the normal desktop host window. With `EnableMainWindowDesktopLayer`, this window is moved to the desktop layer so it does not cover ordinary apps.
+- `FusedDesktopSurface`: fused desktop component windows such as `DesktopWidgetWindow` and `TransparentOverlayWindow`. These continue to use `IWindowBottomMostService` and their existing click-through region service.
+- `AirApp`: independent Air APP windows. These are ordinary app windows and do not use desktop-layer services or global `Topmost` promotion.
+
+## Service Boundary
+
+`IMainWindowDesktopLayerService` is dedicated to the main window only. It does not reuse fused desktop passthrough services because the main window must stay interactive.
+
+Windows behavior:
+
+- Save original parent, style, and extended style before enabling.
+- Try to attach the main window to the desktop icon host.
+- If that host is not found, use `HWND_BOTTOM`.
+- On disable, restore the saved parent and styles as best effort.
+
+Non-Windows behavior:
+
+- Keep a null implementation.
+- Log that the platform is unsupported.
+
+## Settings Flow
+
+The developer settings page owns confirmation UX for conflicts:
+
+- Fused desktop toggle and main-window desktop-layer toggle are one-way bound.
+- Toggle click handlers ask for confirmation before saving conflicting states.
+- The view model writes both keys together so runtime listeners receive a coherent change set.
+
+## Runtime Flow
+
+Main-window restore paths call `ActivateOrRefreshMainWindowLayer`.
+
+- If `EnableMainWindowDesktopLayer` is enabled, the app refreshes the desktop-layer attachment and hides the taskbar entry.
+- If disabled, the app restores ordinary activation behavior, including the existing temporary foreground promotion.
+
+Settings changes call both fused desktop and main-window desktop-layer runtime application paths so switching modes is immediate.

.trae/specs/main-window-desktop-layer/requirements.md

@@ -0,0 +1,20 @@
+# Main Window Desktop Layer
+
+## Requirements
+
+- Add a developer option named `EnableMainWindowDesktopLayer`.
+- When enabled, the main Lan Mountain desktop window behaves like a desktop-surface window: ordinary application windows can stay above it.
+- The feature is implemented as desktop-layer or bottom placement, not as `Topmost`.
+- The option is mutually exclusive with `EnableFusedDesktop`.
+- Enabling main-window desktop layer while fused desktop is enabled must ask for confirmation, then disable fused desktop on confirm or roll back on cancel.
+- Enabling fused desktop while main-window desktop layer is enabled must ask for confirmation, then disable main-window desktop layer on confirm or roll back on cancel.
+- Air APP windows remain ordinary application windows and must not be attached to the desktop layer.
+- On Windows, the main window should attach to the desktop icon host when available and fall back to `HWND_BOTTOM` when unavailable.
+- On non-Windows platforms, the setting may exist but the layer service is a no-op and must not throw.
+
+## Acceptance
+
+- Opening another app above Lan Mountain Desktop keeps that app visible when main-window desktop layer is enabled.
+- Restoring the main window from tray keeps the desktop-layer behavior and does not perform a temporary `Topmost` promotion.
+- Turning the option off restores normal main-window behavior as far as possible.
+- Fused desktop component windows keep their existing bottom-most behavior and remain isolated from the main-window service.

.trae/specs/main-window-desktop-layer/tasks.md

@@ -0,0 +1,10 @@
+# Main Window Desktop Layer Tasks
+
+- [x] Add `EnableMainWindowDesktopLayer` to app settings with a disabled default.
+- [x] Add developer settings UI and localization strings.
+- [x] Add confirmation flow for mutual exclusion with fused desktop.
+- [x] Add a dedicated main-window desktop-layer service.
+- [x] Wire main-window creation, restore, tray fallback, settings changes, and shutdown cleanup to the service.
+- [x] Keep Air APP windows outside this layer service.
+- [x] Add static regression tests for settings, restore paths, and service boundaries.
+- [ ] Perform manual Windows z-order validation with real apps.

.trae/specs/update-settings-fluent-controls/spec.md

@@ -0,0 +1,25 @@
+# Update Settings Fluent Controls
+
+## Goal
+
+Make the Settings > Update page the single user-facing control surface for the host update flow.
+
+## Requirements
+
+- The page uses Fluent Avalonia settings controls for update status, release facts, update behavior, and transfer controls.
+- Users can choose update channel, download source, update mode, and download thread count.
+- Update mode options are:
+  - Manual: do not automatically download or install.
+  - Silent Download: check and download in the background, then wait for user installation confirmation.
+  - Silent Install: check and download in the background, then apply when the app exits.
+- Users can opt into forced reinstall. When enabled, the update check targets the current version manifest where available and the UI labels the next payload as reinstall.
+- The page displays whether the current payload is an incremental update or reinstall/full installer.
+- The page exposes pause, resume, and cancel actions for resumable downloads and install recovery.
+- Existing PloNDS/FileMap incremental update and Launcher rollback ownership remain unchanged.
+
+## Acceptance
+
+- `UpdateSettingsPage` shows Fluent Avalonia controls for channel, mode, thread count, forced reinstall, pause/resume, and cancel.
+- `UpdateSettingsState` persists forced reinstall alongside other update preferences.
+- Automatic startup checks skip manual mode, download in silent download/silent install modes, and leave installation to explicit user action or exit-time apply.
+- Build succeeds for `LanMountainDesktop.slnx`.

LanMountainDesktop.Tests/DesktopEditOverlayPresenterTests.cs

@@ -0,0 +1,38 @@
+using System.Linq;
+using Avalonia;
+using Avalonia.Controls;
+using LanMountainDesktop.DesktopEditing;
+using Xunit;
+
+namespace LanMountainDesktop.Tests;
+
+public sealed class DesktopEditOverlayPresenterTests
+{
+    [Fact]
+    public void CompositionOffsetHelperFallsBackWhenVisualIsUnavailable()
+    {
+        var service = new CompositionVisualAnimationService(_ => null);
+        var target = new Border();
+
+        var result = service.TrySetOffset(target, new Point(12, 34));
+
+        Assert.False(result);
+        Assert.False(service.TrySetOpacity(target, 0.5));
+        Assert.False(service.TrySetUniformScale(target, 1.05));
+    }
+
+    [Fact]
+    public void PreviewRectUsesCanvasPlacementWhenCompositionIsUnavailable()
+    {
+        var presenter = new DesktopEditOverlayPresenter(new CompositionVisualAnimationService(_ => null));
+        var root = Assert.IsType<Canvas>(presenter.Root);
+
+        presenter.SetPreviewRect(new Rect(12, 34, 180, 120));
+
+        var ghost = root.Children.OfType<DesktopEditGhostView>().Single();
+        Assert.Equal(12, Canvas.GetLeft(ghost));
+        Assert.Equal(34, Canvas.GetTop(ghost));
+        Assert.Equal(180, ghost.Width);
+        Assert.Equal(120, ghost.Height);
+    }
+}

LanMountainDesktop.Tests/WindowLayerIsolationTests.cs

@@ -64,6 +64,63 @@ public sealed class WindowLayerIsolationTests
         Assert.Contains("window.RefreshDesktopLayer()", source);
     }
 
+    [Fact]
+    public void MainWindowDesktopLayerService_DoesNotUseFusedDesktopPassthroughBoundary()
+    {
+        var source = ReadRepositoryFile("LanMountainDesktop", "Services", "MainWindowDesktopLayerService.cs");
+
+        Assert.Contains("IMainWindowDesktopLayerService", source);
+        Assert.Contains("SetParent", source);
+        Assert.Contains("HWND_BOTTOM", source);
+        Assert.DoesNotContain("WindowBottomMostServiceFactory", source);
+        Assert.DoesNotContain("IRegionPassthroughService", source);
+        Assert.DoesNotContain("SetInteractiveRegions", source);
+        Assert.DoesNotContain("HTTRANSPARENT", source);
+        Assert.DoesNotContain("WS_EX_NOACTIVATE", source);
+    }
+
+    [Fact]
+    public void MainWindowRestorePaths_UseDesktopLayerAwareActivation()
+    {
+        var source = ReadRepositoryFile("LanMountainDesktop", "App.axaml.cs");
+        var restoreSource = ExtractMethodSource(source, "RestoreOrCreateMainWindowCore");
+        var trayFallbackSource = ExtractMethodSource(source, "RecoverFromTrayUnavailable");
+        var applyLayerSource = ExtractMethodSource(source, "ApplyMainWindowDesktopLayerRuntimeState");
+
+        Assert.Contains("ActivateOrRefreshMainWindowLayer(mainWindow", restoreSource);
+        Assert.DoesNotContain("Topmost = true", restoreSource);
+
+        Assert.Contains("ActivateOrRefreshMainWindowLayer(mainWindow", trayFallbackSource);
+        Assert.DoesNotContain("Topmost = true", trayFallbackSource);
+
+        Assert.Contains("FusedDesktopManagerServiceFactory.GetOrCreate().Shutdown()", applyLayerSource);
+    }
+
+    [Fact]
+    public void AppSettingsSnapshot_MainWindowDesktopLayerDefaultsToDisabled()
+    {
+        Assert.False(new LanMountainDesktop.Models.AppSettingsSnapshot().EnableMainWindowDesktopLayer);
+    }
+
+    [Fact]
+    public void DeveloperSettings_DefinesMutuallyExclusiveDesktopLayerToggles()
+    {
+        var viewModelSource = ReadRepositoryFile("LanMountainDesktop", "ViewModels", "SettingsViewModels.cs");
+        var pageSource = ReadRepositoryFile("LanMountainDesktop", "Views", "SettingsPages", "DevSettingsPage.axaml.cs");
+        var xamlSource = ReadRepositoryFile("LanMountainDesktop", "Views", "SettingsPages", "DevSettingsPage.axaml");
+
+        Assert.Contains("EnableMainWindowDesktopLayer", viewModelSource);
+        Assert.Contains("ApplyFusedDesktopPreference", viewModelSource);
+        Assert.Contains("ApplyMainWindowDesktopLayerPreference", viewModelSource);
+        Assert.Contains("nameof(AppSettingsSnapshot.EnableFusedDesktop)", viewModelSource);
+        Assert.Contains("nameof(AppSettingsSnapshot.EnableMainWindowDesktopLayer)", viewModelSource);
+
+        Assert.Contains("ConfirmDesktopLayerSwitchAsync", pageSource);
+        Assert.Contains("OnFusedDesktopToggleChanged", xamlSource);
+        Assert.Contains("OnMainWindowDesktopLayerToggleChanged", xamlSource);
+        Assert.Contains("Mode=OneWay", xamlSource);
+    }
+
     private static string ReadRepositoryFile(params string[] segments)
     {
         var directory = new DirectoryInfo(AppContext.BaseDirectory);
@@ -85,4 +142,37 @@ public sealed class WindowLayerIsolationTests
 
         throw new FileNotFoundException($"Could not locate repository file '{Path.Combine(segments)}'.");
     }
+
+    private static string ExtractMethodSource(string source, string methodName)
+    {
+        var methodIndex = source.IndexOf($"private bool {methodName}(", StringComparison.Ordinal);
+        if (methodIndex < 0)
+        {
+            methodIndex = source.IndexOf($"private void {methodName}(", StringComparison.Ordinal);
+        }
+
+        Assert.True(methodIndex >= 0, $"Could not locate method '{methodName}'.");
+
+        var braceIndex = source.IndexOf('{', methodIndex);
+        Assert.True(braceIndex >= 0, $"Could not locate method body for '{methodName}'.");
+
+        var depth = 0;
+        for (var i = braceIndex; i < source.Length; i++)
+        {
+            if (source[i] == '{')
+            {
+                depth++;
+            }
+            else if (source[i] == '}')
+            {
+                depth--;
+                if (depth == 0)
+                {
+                    return source.Substring(methodIndex, i - methodIndex + 1);
+                }
+            }
+        }
+
+        throw new InvalidOperationException($"Could not extract method '{methodName}'.");
+    }
 }

LanMountainDesktop/App.axaml.cs

@@ -57,6 +57,7 @@ public partial class App : Application
     private readonly IHostApplicationLifecycle _hostApplicationLifecycle = new HostApplicationLifecycleService();
     private readonly HostShutdownGate _shutdownGate = new();
     private readonly IDetachedComponentLibraryWindowService _detachedComponentLibraryWindowService = new DetachedComponentLibraryWindowService();
+    private readonly IMainWindowDesktopLayerService _mainWindowDesktopLayerService = MainWindowDesktopLayerServiceFactory.GetOrCreate();
     private readonly ILocationService _locationService = HostLocationServiceProvider.GetOrCreate();
     private readonly DateTimeOffset _startupAt = DateTimeOffset.UtcNow;
     private readonly string _launchSource = LauncherRuntimeMetadata.GetLaunchSource(Environment.GetCommandLineArgs()) ?? "normal";
@@ -897,7 +898,7 @@ public partial class App : Application
             var mainWindow = GetOrCreateMainWindow(desktop, source);
             mainWindow.PrepareEnterAnimation();
 
-            mainWindow.ShowInTaskbar = ShouldShowMainWindowInTaskbar();
+            mainWindow.ShowInTaskbar = ShouldShowMainWindowInTaskbar() && !IsMainWindowDesktopLayerEnabled();
 
             if (!mainWindow.IsVisible)
             {
@@ -917,9 +918,7 @@ public partial class App : Application
                 mainWindow.WindowState = WindowState.FullScreen;
             }
 
-            mainWindow.Activate();
-            mainWindow.Topmost = true;
-            mainWindow.Topmost = false;
+            ActivateOrRefreshMainWindowLayer(mainWindow, $"Restore:{source}");
 
             Dispatcher.UIThread.Post(() =>
             {
@@ -1113,9 +1112,19 @@ public partial class App : Application
 
             if (fusedDesktopChanged)
             {
+                ApplyFusedDesktopRuntimeState();
                 RefreshFusedDesktopMenuItemVisibility();
             }
 
+            var mainWindowDesktopLayerChanged =
+                refreshAll ||
+                changedKeys.Contains(nameof(AppSettingsSnapshot.EnableMainWindowDesktopLayer), StringComparer.OrdinalIgnoreCase);
+
+            if (mainWindowDesktopLayerChanged)
+            {
+                ApplyMainWindowDesktopLayerRuntimeState("SettingsChanged");
+            }
+
             var showInTaskbarChanged =
                 refreshAll ||
                 changedKeys.Contains(nameof(AppSettingsSnapshot.ShowInTaskbar), StringComparer.OrdinalIgnoreCase);
@@ -1313,7 +1322,7 @@ public partial class App : Application
         var mainWindow = new MainWindow
         {
             DataContext = new MainWindowViewModel(),
-            ShowInTaskbar = ShouldShowMainWindowInTaskbar()
+            ShowInTaskbar = ShouldShowMainWindowInTaskbar() && !IsMainWindowDesktopLayerEnabled()
         };
 
         _mainWindowOpened = false;
@@ -1351,6 +1360,7 @@ public partial class App : Application
         {
             mainWindow.Opened -= OnMainWindowOpened;
             _mainWindowOpened = true;
+            ApplyMainWindowDesktopLayerRuntimeState("MainWindowOpened");
             _loadingStateManager?.CompleteItem("system.init", "System initialization completed.");
 
             if (TryApplyStartupPresentation(mainWindow))
@@ -1428,6 +1438,7 @@ public partial class App : Application
 
         if (_mainWindow is not null)
         {
+            _mainWindowDesktopLayerService.Disable(_mainWindow);
             _mainWindow.Closing -= OnMainWindowClosing;
             _mainWindow.Closed -= OnMainWindowClosed;
             _mainWindow.PropertyChanged -= OnMainWindowPropertyChanged;
@@ -1473,6 +1484,7 @@ public partial class App : Application
         mainWindow.Closing -= OnMainWindowClosing;
         mainWindow.Closed -= OnMainWindowClosed;
         mainWindow.PropertyChanged -= OnMainWindowPropertyChanged;
+        _mainWindowDesktopLayerService.Disable(mainWindow);
 
         if (ReferenceEquals(_mainWindow, mainWindow))
         {
@@ -1614,16 +1626,83 @@ public partial class App : Application
             mainWindow.WindowState = WindowState.FullScreen;
         }
 
-        mainWindow.Activate();
-        mainWindow.Topmost = true;
-        mainWindow.Topmost = false;
+        ActivateOrRefreshMainWindowLayer(mainWindow, $"TrayFallbackForeground:{source}");
         SetDesktopShellState(DesktopShellState.ForegroundDesktop, $"TrayFallbackForeground:{source}");
         ReportStartupProgress(StartupStage.DesktopVisible, 100, "Desktop restored because tray was unavailable.");
     }
 
     private bool ShouldShowMainWindowInTaskbar()
     {
-        return _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App).ShowInTaskbar;
+        var snapshot = _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App);
+        return snapshot.ShowInTaskbar && !snapshot.EnableMainWindowDesktopLayer;
+    }
+
+    private bool IsMainWindowDesktopLayerEnabled()
+    {
+        return _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App).EnableMainWindowDesktopLayer;
+    }
+
+    private void ActivateOrRefreshMainWindowLayer(MainWindow mainWindow, string source)
+    {
+        if (IsMainWindowDesktopLayerEnabled())
+        {
+            mainWindow.ShowInTaskbar = false;
+            _mainWindowDesktopLayerService.EnableOrRefresh(mainWindow);
+            AppLogger.Info("DesktopShell", $"Main window kept on desktop layer. Source='{source}'.");
+            return;
+        }
+
+        _mainWindowDesktopLayerService.Disable(mainWindow);
+        mainWindow.Activate();
+        mainWindow.Topmost = true;
+        mainWindow.Topmost = false;
+    }
+
+    private void ApplyMainWindowDesktopLayerRuntimeState(string source)
+    {
+        if (_mainWindow is null)
+        {
+            return;
+        }
+
+        if (IsMainWindowDesktopLayerEnabled())
+        {
+            ExitFusedDesktopEditModeFromUi(closeLibrary: true);
+            FusedDesktopManagerServiceFactory.GetOrCreate().Shutdown();
+            _mainWindow.ShowInTaskbar = false;
+            _mainWindowDesktopLayerService.EnableOrRefresh(_mainWindow);
+            AppLogger.Info("DesktopShell", $"Main window desktop layer enabled. Source='{source}'.");
+            return;
+        }
+
+        _mainWindowDesktopLayerService.Disable(_mainWindow);
+        _mainWindow.ShowInTaskbar = ShouldShowMainWindowInTaskbar();
+        AppLogger.Info("DesktopShell", $"Main window desktop layer disabled. Source='{source}'.");
+    }
+
+    private void ApplyFusedDesktopRuntimeState()
+    {
+        var snapshot = _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App);
+        try
+        {
+            if (snapshot.EnableFusedDesktop)
+            {
+                if (_mainWindow is not null)
+                {
+                    _mainWindowDesktopLayerService.Disable(_mainWindow);
+                }
+
+                FusedDesktopManagerServiceFactory.GetOrCreate().Initialize();
+                return;
+            }
+
+            ExitFusedDesktopEditModeFromUi(closeLibrary: true);
+            FusedDesktopManagerServiceFactory.GetOrCreate().Shutdown();
+        }
+        catch (Exception ex)
+        {
+            AppLogger.Warn("FusedDesktop", "Failed to apply fused desktop runtime state.", ex);
+        }
     }
 
     private bool EnsureTaskbarEntry(string source)

LanMountainDesktop/DesktopEditing/CompositionVisualAnimationService.cs

@@ -0,0 +1,82 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Rendering.Composition;
+
+namespace LanMountainDesktop.DesktopEditing;
+
+internal sealed class CompositionVisualAnimationService
+{
+    private readonly Func<Visual, CompositionVisual?> _getVisual;
+
+    public CompositionVisualAnimationService()
+        : this(ElementComposition.GetElementVisual)
+    {
+    }
+
+    internal CompositionVisualAnimationService(Func<Visual, CompositionVisual?> getVisual)
+    {
+        _getVisual = getVisual;
+    }
+
+    public bool TrySetOffset(Control target, Point offset)
+    {
+        return TryApply(target, visual =>
+        {
+            visual.StopAnimation(nameof(visual.Offset));
+            visual.Offset = visual.Offset with
+            {
+                X = offset.X,
+                Y = offset.Y
+            };
+        });
+    }
+
+    public bool TrySetOpacity(Control target, double opacity)
+    {
+        return TryApply(target, visual =>
+        {
+            visual.StopAnimation(nameof(visual.Opacity));
+            visual.Opacity = (float)Math.Clamp(opacity, 0, 1);
+        });
+    }
+
+    public bool TrySetUniformScale(Control target, double scale)
+    {
+        return TryApply(target, visual =>
+        {
+            var clampedScale = Math.Clamp(scale, 0.01, 64);
+            visual.StopAnimation(nameof(visual.Scale));
+            visual.Scale = visual.Scale with
+            {
+                X = clampedScale,
+                Y = clampedScale,
+                Z = 1
+            };
+        });
+    }
+
+    public bool TryResetOffset(Control target)
+    {
+        return TrySetOffset(target, new Point());
+    }
+
+    private bool TryApply(Control target, Action<CompositionVisual> apply)
+    {
+        try
+        {
+            var visual = _getVisual(target);
+            if (visual is null)
+            {
+                return false;
+            }
+
+            apply(visual);
+            return true;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+}

LanMountainDesktop/DesktopEditing/DesktopEditOverlayPresenter.cs

@@ -27,11 +27,14 @@ internal sealed class DesktopEditOverlayPresenter
     private readonly DesktopEditGhostView _ghostView;
     private readonly Border _candidateOutline;
     private readonly ScaleTransform _candidateScale = new(1, 1);
+    private readonly CompositionVisualAnimationService _visualAnimationService;
 
     private Rect? _previewRect;
     private Rect? _candidateRect;
     private bool _isInvalid;
     private bool _isVisible;
+    private bool _ghostUsesCompositionOffset;
+    private bool _candidateUsesCompositionOffset;
     private int _dismissVersion;
 
     private readonly SolidColorBrush _candidateBrush = new(Color.Parse("#FF0A84FF"));
@@ -40,7 +43,14 @@ internal sealed class DesktopEditOverlayPresenter
     private readonly SolidColorBrush _candidateInvalidFillBrush = new(Color.Parse("#14FF3B30"));
 
     public DesktopEditOverlayPresenter()
+        : this(new CompositionVisualAnimationService())
     {
+    }
+
+    internal DesktopEditOverlayPresenter(CompositionVisualAnimationService visualAnimationService)
+    {
+        _visualAnimationService = visualAnimationService;
+
         _ghostView = new DesktopEditGhostView
         {
             IsHitTestVisible = false,
@@ -276,8 +286,7 @@ internal sealed class DesktopEditOverlayPresenter
         var rect = _previewRect.Value;
         _ghostView.Width = Math.Max(1, rect.Width);
         _ghostView.Height = Math.Max(1, rect.Height);
-        Canvas.SetLeft(_ghostView, rect.X);
-        Canvas.SetTop(_ghostView, rect.Y);
+        SetOverlayOffset(_ghostView, new Point(rect.X, rect.Y), ref _ghostUsesCompositionOffset);
         _ghostView.UpdatePreviewMetrics(rect.Width, rect.Height);
     }
 
@@ -294,8 +303,7 @@ internal sealed class DesktopEditOverlayPresenter
         _candidateOutline.IsVisible = true;
         _candidateOutline.Width = Math.Max(1, rect.Width);
         _candidateOutline.Height = Math.Max(1, rect.Height);
-        Canvas.SetLeft(_candidateOutline, rect.X);
-        Canvas.SetTop(_candidateOutline, rect.Y);
+        SetOverlayOffset(_candidateOutline, new Point(rect.X, rect.Y), ref _candidateUsesCompositionOffset);
 
         var cornerRadius = Math.Clamp(Math.Min(rect.Width, rect.Height) * 0.11, 14, 26);
         _candidateOutline.CornerRadius = new CornerRadius(cornerRadius);
@@ -325,6 +333,26 @@ internal sealed class DesktopEditOverlayPresenter
         return new Rect(rect.X, rect.Y, width, height);
     }
 
+    private void SetOverlayOffset(Control target, Point position, ref bool usesCompositionOffset)
+    {
+        if (_visualAnimationService.TrySetOffset(target, position))
+        {
+            Canvas.SetLeft(target, 0);
+            Canvas.SetTop(target, 0);
+            usesCompositionOffset = true;
+            return;
+        }
+
+        if (usesCompositionOffset)
+        {
+            _visualAnimationService.TryResetOffset(target);
+            usesCompositionOffset = false;
+        }
+
+        Canvas.SetLeft(target, position.X);
+        Canvas.SetTop(target, position.Y);
+    }
+
     private static DoubleTransition CreateScaleTransition(AvaloniaProperty property, TimeSpan duration) =>
         new()
         {

LanMountainDesktop/Localization/en-US.json

@@ -802,6 +802,13 @@
     "settings.dev.three_finger_description":  "Enable desktop page switching gestures when the current platform supports them.",
     "settings.dev.fused_header":  "Fused desktop experience",
     "settings.dev.fused_description":  "Enable the fused desktop shell and its related experimental entry points.",
+    "settings.dev.main_window_desktop_layer_header":  "Prevent covering other apps",
+    "settings.dev.main_window_desktop_layer_description":  "Keep the main desktop window on the desktop layer so ordinary app windows can stay above it.",
+    "settings.dev.desktop_layer_conflict_title":  "Switch desktop layer mode?",
+    "settings.dev.desktop_layer_conflict_enable_main":  "Main desktop layer mode and fused desktop cannot run at the same time. Enabling this option will turn off fused desktop.",
+    "settings.dev.desktop_layer_conflict_enable_fused":  "Fused desktop and main desktop layer mode cannot run at the same time. Enabling fused desktop will turn off main desktop layer mode.",
+    "settings.dev.desktop_layer_conflict_confirm":  "Switch",
+    "settings.dev.desktop_layer_conflict_cancel":  "Cancel",
     "settings.dev.plugin_path_header":  "Development plugin path",
     "settings.dev.plugin_path_description":  "Load a local plugin output directory for iterative debugging without packaging.",
     "settings.dev.plugin_path_placeholder":  "e.g. C:\\path\\to\\plugin\\bin\\Debug\\net10.0",

LanMountainDesktop/Localization/zh-CN.json

@@ -741,6 +741,13 @@
     "settings.dev.three_finger_description":  "在当前平台支持时，启用手势在桌面分页间切换。",
     "settings.dev.fused_header":  "融合桌面体验",
     "settings.dev.fused_description":  "启用融合桌面壳及相关实验入口。",
+    "settings.dev.main_window_desktop_layer_header":  "防遮挡其它应用窗口",
+    "settings.dev.main_window_desktop_layer_description":  "让主桌面窗口保持在桌面层，使普通应用窗口可以显示在它上方。",
+    "settings.dev.desktop_layer_conflict_title":  "切换桌面层模式？",
+    "settings.dev.desktop_layer_conflict_enable_main":  "主桌面桌面层模式不能和融合桌面同时运行。开启此选项将关闭融合桌面。",
+    "settings.dev.desktop_layer_conflict_enable_fused":  "融合桌面不能和主桌面桌面层模式同时运行。开启融合桌面将关闭主桌面桌面层模式。",
+    "settings.dev.desktop_layer_conflict_confirm":  "切换",
+    "settings.dev.desktop_layer_conflict_cancel":  "取消",
     "settings.dev.plugin_path_header":  "开发插件路径",
     "settings.dev.plugin_path_description":  "加载本地插件输出目录以便免打包迭代调试。",
     "settings.dev.plugin_path_placeholder":  "例如：C:\\path\\to\\plugin\\bin\\Debug\\net10.0",

LanMountainDesktop/Models/AppSettingsSnapshot.cs

@@ -99,6 +99,8 @@ public sealed class AppSettingsSnapshot
 
     public int UpdateDownloadThreads { get; set; } = 4;
 
+    public bool ForceUpdateReinstall { get; set; }
+
     public string? PendingUpdateInstallerPath { get; set; }
 
     public string? PendingUpdateVersion { get; set; }
@@ -182,6 +184,8 @@ public sealed class AppSettingsSnapshot
 
     public bool EnableFusedDesktop { get; set; } = false;
 
+    public bool EnableMainWindowDesktopLayer { get; set; } = false;
+
     public List<string> DisabledPluginIds { get; set; } = [];
 
     public bool IsDevModeEnabled { get; set; }

LanMountainDesktop/Services/FusedDesktopManagerService.cs

@@ -20,6 +20,7 @@ public interface IFusedDesktopManagerService
     void EnterEditMode();
     void ExitEditMode();
     void ReloadWidgets();
+    void Shutdown();
 }
 
 /// <summary>
@@ -158,6 +159,18 @@ internal sealed class FusedDesktopManagerService : IFusedDesktopManagerService
         }
     }
 
+    public void Shutdown()
+    {
+        _isEditMode = false;
+        foreach (var window in _widgetWindows.Values)
+        {
+            window.Close();
+        }
+
+        _widgetWindows.Clear();
+        AppLogger.Info("FusedDesktop", "Fused desktop manager shut down.");
+    }
+
     private DesktopWidgetWindow? CreateWidgetWindow(FusedDesktopComponentPlacementSnapshot placement)
     {
         EnsureRegistries();

LanMountainDesktop/Services/MainWindowDesktopLayerService.cs

@@ -0,0 +1,272 @@
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using Avalonia.Controls;
+
+namespace LanMountainDesktop.Services;
+
+public interface IMainWindowDesktopLayerService
+{
+    bool IsSupported { get; }
+    void EnableOrRefresh(Window window);
+    void Disable(Window window);
+}
+
+public static class MainWindowDesktopLayerServiceFactory
+{
+    private static readonly object Gate = new();
+    private static IMainWindowDesktopLayerService? _instance;
+
+    public static IMainWindowDesktopLayerService GetOrCreate()
+    {
+        lock (Gate)
+        {
+            return _instance ??= OperatingSystem.IsWindows()
+                ? new WindowsMainWindowDesktopLayerService()
+                : new NullMainWindowDesktopLayerService();
+        }
+    }
+}
+
+internal sealed class WindowsMainWindowDesktopLayerService : IMainWindowDesktopLayerService
+{
+    private const int GWL_STYLE = -16;
+    private const int GWL_EXSTYLE = -20;
+
+    private const long WS_CHILD = 0x40000000L;
+    private const long WS_POPUP = 0x80000000L;
+    private const long WS_CAPTION = 0x00C00000L;
+    private const long WS_THICKFRAME = 0x00040000L;
+    private const long WS_MINIMIZEBOX = 0x00020000L;
+    private const long WS_MAXIMIZEBOX = 0x00010000L;
+    private const long WS_SYSMENU = 0x00080000L;
+
+    private const uint SWP_NOSIZE = 0x0001;
+    private const uint SWP_NOMOVE = 0x0002;
+    private const uint SWP_NOACTIVATE = 0x0010;
+    private const uint SWP_SHOWWINDOW = 0x0040;
+    private const uint SWP_FRAMECHANGED = 0x0020;
+
+    private static readonly IntPtr HWND_TOP = IntPtr.Zero;
+    private static readonly IntPtr HWND_BOTTOM = new(1);
+
+    private readonly object _gate = new();
+    private readonly Dictionary<IntPtr, WindowRestoreState> _restoreStates = [];
+
+    public bool IsSupported => true;
+
+    public void EnableOrRefresh(Window window)
+    {
+        ArgumentNullException.ThrowIfNull(window);
+
+        var handle = GetWindowHandle(window);
+        if (handle == IntPtr.Zero)
+        {
+            window.Opened -= OnDeferredOpened;
+            window.Opened += OnDeferredOpened;
+            return;
+        }
+
+        EnableOrRefresh(handle);
+    }
+
+    public void Disable(Window window)
+    {
+        ArgumentNullException.ThrowIfNull(window);
+        window.Opened -= OnDeferredOpened;
+
+        var handle = GetWindowHandle(window);
+        if (handle == IntPtr.Zero)
+        {
+            return;
+        }
+
+        WindowRestoreState? restoreState;
+        lock (_gate)
+        {
+            if (!_restoreStates.Remove(handle, out restoreState))
+            {
+                return;
+            }
+        }
+
+        try
+        {
+            _ = SetParent(handle, restoreState.Parent);
+            SetWindowLongPtr(handle, GWL_STYLE, restoreState.Style);
+            SetWindowLongPtr(handle, GWL_EXSTYLE, restoreState.ExStyle);
+            _ = SetWindowPos(
+                handle,
+                HWND_TOP,
+                0,
+                0,
+                0,
+                0,
+                SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE | SWP_FRAMECHANGED | SWP_SHOWWINDOW);
+            AppLogger.Info("MainWindowDesktopLayer", $"Disabled desktop layer. Window={handle}.");
+        }
+        catch (Exception ex)
+        {
+            AppLogger.Warn("MainWindowDesktopLayer", $"Failed to disable desktop layer. Window={handle}.", ex);
+        }
+    }
+
+    private void OnDeferredOpened(object? sender, EventArgs e)
+    {
+        if (sender is not Window window)
+        {
+            return;
+        }
+
+        window.Opened -= OnDeferredOpened;
+        EnableOrRefresh(window);
+    }
+
+    private void EnableOrRefresh(IntPtr handle)
+    {
+        if (handle == IntPtr.Zero || !IsWindow(handle))
+        {
+            return;
+        }
+
+        SaveRestoreStateIfNeeded(handle);
+        var desktopHost = ResolveDesktopIconHost();
+        if (desktopHost != IntPtr.Zero && IsWindow(desktopHost))
+        {
+            ApplyDesktopChildStyle(handle);
+            if (GetParent(handle) != desktopHost)
+            {
+                _ = SetParent(handle, desktopHost);
+            }
+
+            _ = SetWindowPos(
+                handle,
+                HWND_TOP,
+                0,
+                0,
+                0,
+                0,
+                SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE | SWP_FRAMECHANGED | SWP_SHOWWINDOW);
+            AppLogger.Info("MainWindowDesktopLayer", $"Enabled desktop layer. Window={handle}; Host={desktopHost}.");
+            return;
+        }
+
+        _ = SetWindowPos(handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE | SWP_SHOWWINDOW);
+        AppLogger.Warn("MainWindowDesktopLayer", $"Desktop icon host not found. Falling back to HWND_BOTTOM. Window={handle}.");
+    }
+
+    private void SaveRestoreStateIfNeeded(IntPtr handle)
+    {
+        lock (_gate)
+        {
+            if (_restoreStates.ContainsKey(handle))
+            {
+                return;
+            }
+
+            _restoreStates[handle] = new WindowRestoreState(
+                GetParent(handle),
+                GetWindowLongPtr(handle, GWL_STYLE),
+                GetWindowLongPtr(handle, GWL_EXSTYLE));
+        }
+    }
+
+    private static void ApplyDesktopChildStyle(IntPtr handle)
+    {
+        var style = GetWindowLongPtr(handle, GWL_STYLE).ToInt64();
+        style |= WS_CHILD;
+        style &= ~(WS_POPUP | WS_CAPTION | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX | WS_SYSMENU);
+        SetWindowLongPtr(handle, GWL_STYLE, new IntPtr(style));
+    }
+
+    private static IntPtr ResolveDesktopIconHost()
+    {
+        var topLevelWindows = new List<IntPtr>();
+        EnumWindows((handle, _) =>
+        {
+            topLevelWindows.Add(handle);
+            return true;
+        }, IntPtr.Zero);
+
+        foreach (var topLevelWindow in topLevelWindows)
+        {
+            var worker = FindWindowEx(topLevelWindow, IntPtr.Zero, "WorkerW", null);
+            if (worker == IntPtr.Zero)
+            {
+                continue;
+            }
+
+            var defView = FindWindowEx(worker, IntPtr.Zero, "SHELLDLL_DefView", null);
+            if (defView != IntPtr.Zero)
+            {
+                return defView;
+            }
+        }
+
+        foreach (var topLevelWindow in topLevelWindows)
+        {
+            var defView = FindWindowEx(topLevelWindow, IntPtr.Zero, "SHELLDLL_DefView", null);
+            if (defView != IntPtr.Zero)
+            {
+                return defView;
+            }
+        }
+
+        return IntPtr.Zero;
+    }
+
+    private static IntPtr GetWindowHandle(Window window)
+    {
+        try
+        {
+            return window.TryGetPlatformHandle()?.Handle ?? IntPtr.Zero;
+        }
+        catch
+        {
+            return IntPtr.Zero;
+        }
+    }
+
+    private sealed record WindowRestoreState(IntPtr Parent, IntPtr Style, IntPtr ExStyle);
+
+    private delegate bool EnumWindowsProc(IntPtr handle, IntPtr lParam);
+
+    [DllImport("user32.dll", EntryPoint = "GetWindowLongPtr")]
+    private static extern IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex);
+
+    [DllImport("user32.dll", EntryPoint = "SetWindowLongPtr")]
+    private static extern IntPtr SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);
+
+    [DllImport("user32.dll")]
+    private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint flags);
+
+    [DllImport("user32.dll", SetLastError = true)]
+    private static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr GetParent(IntPtr hWnd);
+
+    [DllImport("user32.dll")]
+    private static extern bool IsWindow(IntPtr hWnd);
+
+    [DllImport("user32.dll", SetLastError = true)]
+    private static extern IntPtr FindWindowEx(IntPtr hParent, IntPtr hChildAfter, string? lpszClass, string? lpszWindow);
+
+    [DllImport("user32.dll", SetLastError = true)]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
+}
+
+internal sealed class NullMainWindowDesktopLayerService : IMainWindowDesktopLayerService
+{
+    public bool IsSupported => false;
+
+    public void EnableOrRefresh(Window window)
+    {
+        AppLogger.Info("MainWindowDesktopLayer", "Desktop layer requested on an unsupported platform.");
+    }
+
+    public void Disable(Window window)
+    {
+    }
+}

LanMountainDesktop/Services/Settings/SettingsContracts.cs

@@ -89,6 +89,7 @@ public sealed record UpdateSettingsState(
     string UpdateMode,
     string UpdateDownloadSource,
     int UpdateDownloadThreads,
+    bool ForceUpdateReinstall,
     bool UseGhProxyMirror,
     string? PendingUpdateInstallerPath,
     string? PendingUpdateVersion,

LanMountainDesktop/Services/Settings/SettingsDomainServices.cs

@@ -802,6 +802,7 @@ internal sealed class UpdateSettingsService : IUpdateSettingsService, IDisposabl
             UpdateSettingsValues.NormalizeMode(snapshot.UpdateMode),
             UpdateSettingsValues.NormalizeDownloadSource(snapshot.UpdateDownloadSource),
             UpdateSettingsValues.NormalizeDownloadThreads(snapshot.UpdateDownloadThreads),
+            snapshot.ForceUpdateReinstall,
             snapshot.UseGhProxyMirror,
             snapshot.PendingUpdateInstallerPath,
             snapshot.PendingUpdateVersion,
@@ -824,6 +825,7 @@ internal sealed class UpdateSettingsService : IUpdateSettingsService, IDisposabl
         snapshot.UpdateMode = UpdateSettingsValues.NormalizeMode(state.UpdateMode);
         snapshot.UpdateDownloadSource = UpdateSettingsValues.NormalizeDownloadSource(state.UpdateDownloadSource);
         snapshot.UpdateDownloadThreads = UpdateSettingsValues.NormalizeDownloadThreads(state.UpdateDownloadThreads);
+        snapshot.ForceUpdateReinstall = state.ForceUpdateReinstall;
         snapshot.UseGhProxyMirror = state.UseGhProxyMirror;
         snapshot.PendingUpdateInstallerPath = string.IsNullOrWhiteSpace(state.PendingUpdateInstallerPath)
             ? null
@@ -850,6 +852,7 @@ internal sealed class UpdateSettingsService : IUpdateSettingsService, IDisposabl
                 nameof(AppSettingsSnapshot.UpdateMode),
                 nameof(AppSettingsSnapshot.UpdateDownloadSource),
                 nameof(AppSettingsSnapshot.UpdateDownloadThreads),
+                nameof(AppSettingsSnapshot.ForceUpdateReinstall),
                 nameof(AppSettingsSnapshot.UseGhProxyMirror),
                 nameof(AppSettingsSnapshot.PendingUpdateInstallerPath),
                 nameof(AppSettingsSnapshot.PendingUpdateVersion),

LanMountainDesktop/Services/Update/UpdateOrchestrator.cs

@@ -129,11 +129,27 @@ public sealed class UpdateOrchestrator : IDisposable
             UpdateManifest? manifest;
             try
             {
-                manifest = await _manifestProvider.GetLatestAsync(
-                    channel,
-                    LanMountainDesktop.Services.PlondsStaticUpdateService.ResolveCurrentPlatform(),
-                    currentVersion,
-                    operationToken);
+                var platform = LanMountainDesktop.Services.PlondsStaticUpdateService.ResolveCurrentPlatform();
+                manifest = settings.ForceUpdateReinstall
+                    ? await _manifestProvider.GetByVersionAsync(
+                        currentVersionText,
+                        channel,
+                        platform,
+                        operationToken)
+                    : await _manifestProvider.GetLatestAsync(
+                        channel,
+                        platform,
+                        currentVersion,
+                        operationToken);
+
+                if (manifest is null && settings.ForceUpdateReinstall)
+                {
+                    manifest = await _manifestProvider.GetLatestAsync(
+                        channel,
+                        platform,
+                        currentVersion,
+                        operationToken);
+                }
             }
             catch (OperationCanceledException)
             {
@@ -525,7 +541,13 @@ public sealed class UpdateOrchestrator : IDisposable
 
         try
         {
-            await CheckAsync(ct);
+            var report = await CheckAsync(ct);
+            if (!report.IsUpdateAvailable || !CurrentPhase.CanDownload())
+            {
+                return;
+            }
+
+            await DownloadAsync(ct);
         }
         catch (OperationCanceledException)
         {

LanMountainDesktop/Services/UpdateSettingsValues.cs

@@ -10,6 +10,8 @@ public static class UpdateSettingsValues
     public const string ModeManual = "manual";
     public const string ModeDownloadThenConfirm = "download_then_confirm";
     public const string ModeSilentOnExit = "silent_on_exit";
+    public const string ModeSilentDownload = ModeDownloadThenConfirm;
+    public const string ModeSilentInstall = ModeSilentOnExit;
 
     // NOTE: keep constant name for compatibility with existing call sites.
     public const string DownloadSourcePlonds = "plonds-api";

LanMountainDesktop/ViewModels/SettingsViewModels.cs

@@ -2416,6 +2416,9 @@ public sealed partial class DevSettingsPageViewModel : ViewModelBase
     [ObservableProperty]
     private bool _enableFusedDesktop;
 
+    [ObservableProperty]
+    private bool _enableMainWindowDesktopLayer;
+
     [ObservableProperty]
     private string _infoBarTitle = string.Empty;
 
@@ -2440,6 +2443,27 @@ public sealed partial class DevSettingsPageViewModel : ViewModelBase
     [ObservableProperty]
     private string _fusedDescription = string.Empty;
 
+    [ObservableProperty]
+    private string _mainWindowDesktopLayerHeader = string.Empty;
+
+    [ObservableProperty]
+    private string _mainWindowDesktopLayerDescription = string.Empty;
+
+    [ObservableProperty]
+    private string _desktopLayerConflictTitle = string.Empty;
+
+    [ObservableProperty]
+    private string _desktopLayerConflictEnableMainMessage = string.Empty;
+
+    [ObservableProperty]
+    private string _desktopLayerConflictEnableFusedMessage = string.Empty;
+
+    [ObservableProperty]
+    private string _desktopLayerConflictConfirmText = string.Empty;
+
+    [ObservableProperty]
+    private string _desktopLayerConflictCancelText = string.Empty;
+
     [ObservableProperty]
     private string _pluginPathHeader = string.Empty;
 
@@ -2486,6 +2510,13 @@ public sealed partial class DevSettingsPageViewModel : ViewModelBase
         ThreeFingerDescription = L("settings.dev.three_finger_description", "Enable desktop page switching gestures when supported.");
         FusedHeader = L("settings.dev.fused_header", "Fused desktop experience");
         FusedDescription = L("settings.dev.fused_description", "Enable the fused desktop shell and experimental entry points.");
+        MainWindowDesktopLayerHeader = L("settings.dev.main_window_desktop_layer_header", "Prevent covering other apps");
+        MainWindowDesktopLayerDescription = L("settings.dev.main_window_desktop_layer_description", "Keep the main desktop window on the desktop layer so ordinary app windows can stay above it.");
+        DesktopLayerConflictTitle = L("settings.dev.desktop_layer_conflict_title", "Switch desktop layer mode?");
+        DesktopLayerConflictEnableMainMessage = L("settings.dev.desktop_layer_conflict_enable_main", "Main desktop layer mode and fused desktop cannot run at the same time. Enabling this option will turn off fused desktop.");
+        DesktopLayerConflictEnableFusedMessage = L("settings.dev.desktop_layer_conflict_enable_fused", "Fused desktop and main desktop layer mode cannot run at the same time. Enabling fused desktop will turn off main desktop layer mode.");
+        DesktopLayerConflictConfirmText = L("settings.dev.desktop_layer_conflict_confirm", "Switch");
+        DesktopLayerConflictCancelText = L("settings.dev.desktop_layer_conflict_cancel", "Cancel");
         PluginPathHeader = L("settings.dev.plugin_path_header", "Development plugin path");
         PluginPathDescription = L("settings.dev.plugin_path_description", "Load a local plugin output directory without packaging.");
         PluginPathPlaceholder = L("settings.dev.plugin_path_placeholder", "e.g. C:\\path\\to\\plugin\\bin\\Debug\\net10.0");
@@ -2527,6 +2558,12 @@ public sealed partial class DevSettingsPageViewModel : ViewModelBase
         SaveField(nameof(AppSettingsSnapshot.EnableFusedDesktop), value);
     }
 
+    partial void OnEnableMainWindowDesktopLayerChanged(bool value)
+    {
+        if (_isInitializing) return;
+        SaveField(nameof(AppSettingsSnapshot.EnableMainWindowDesktopLayer), value);
+    }
+
     private void LoadSettings()
     {
         var snapshot = _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App);
@@ -2534,6 +2571,7 @@ public sealed partial class DevSettingsPageViewModel : ViewModelBase
         DevPluginPath = snapshot.DevPluginPath ?? string.Empty;
         EnableThreeFingerSwipe = snapshot.EnableThreeFingerSwipe;
         EnableFusedDesktop = snapshot.EnableFusedDesktop;
+        EnableMainWindowDesktopLayer = snapshot.EnableMainWindowDesktopLayer;
     }
 
     private void OnSettingsChanged(object? sender, SettingsChangedEvent e)
@@ -2555,6 +2593,7 @@ public sealed partial class DevSettingsPageViewModel : ViewModelBase
             var snapshot = _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App);
             EnableThreeFingerSwipe = snapshot.EnableThreeFingerSwipe;
             EnableFusedDesktop = snapshot.EnableFusedDesktop;
+            EnableMainWindowDesktopLayer = snapshot.EnableMainWindowDesktopLayer;
         }
         finally
         {
@@ -2573,4 +2612,51 @@ public sealed partial class DevSettingsPageViewModel : ViewModelBase
 
         _settingsFacade.Settings.SaveSnapshot(SettingsScope.App, snapshot, changedKeys: [key]);
     }
+
+    public void ApplyFusedDesktopPreference(bool enabled, bool disableMainWindowDesktopLayer)
+    {
+        var snapshot = _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App);
+        snapshot.EnableFusedDesktop = enabled;
+        if (enabled && disableMainWindowDesktopLayer)
+        {
+            snapshot.EnableMainWindowDesktopLayer = false;
+        }
+
+        SaveDesktopLayerPreferences(snapshot);
+    }
+
+    public void ApplyMainWindowDesktopLayerPreference(bool enabled, bool disableFusedDesktop)
+    {
+        var snapshot = _settingsFacade.Settings.LoadSnapshot<AppSettingsSnapshot>(SettingsScope.App);
+        snapshot.EnableMainWindowDesktopLayer = enabled;
+        if (enabled && disableFusedDesktop)
+        {
+            snapshot.EnableFusedDesktop = false;
+        }
+
+        SaveDesktopLayerPreferences(snapshot);
+    }
+
+    private void SaveDesktopLayerPreferences(AppSettingsSnapshot snapshot)
+    {
+        _settingsFacade.Settings.SaveSnapshot(
+            SettingsScope.App,
+            snapshot,
+            changedKeys:
+            [
+                nameof(AppSettingsSnapshot.EnableFusedDesktop),
+                nameof(AppSettingsSnapshot.EnableMainWindowDesktopLayer)
+            ]);
+
+        _isInitializing = true;
+        try
+        {
+            EnableFusedDesktop = snapshot.EnableFusedDesktop;
+            EnableMainWindowDesktopLayer = snapshot.EnableMainWindowDesktopLayer;
+        }
+        finally
+        {
+            _isInitializing = false;
+        }
+    }
 }

LanMountainDesktop/ViewModels/UpdateSettingsViewModel.cs

@@ -63,9 +63,19 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
     [ObservableProperty] private string _lastCheckedLabel = string.Empty;
     [ObservableProperty] private string _updateTypeLabel = string.Empty;
     [ObservableProperty] private string _channelLabel = string.Empty;
+    [ObservableProperty] private string _channelDescription = string.Empty;
     [ObservableProperty] private string _sourceLabel = string.Empty;
+    [ObservableProperty] private string _sourceDescription = string.Empty;
     [ObservableProperty] private string _modeLabel = string.Empty;
+    [ObservableProperty] private string _modeDescription = string.Empty;
     [ObservableProperty] private string _downloadThreadsLabel = string.Empty;
+    [ObservableProperty] private string _downloadThreadsDescription = string.Empty;
+    [ObservableProperty] private string _forceReinstallLabel = string.Empty;
+    [ObservableProperty] private string _forceReinstallDescription = string.Empty;
+    [ObservableProperty] private string _resumeSupportLabel = string.Empty;
+    [ObservableProperty] private string _resumeSupportDescription = string.Empty;
+    [ObservableProperty] private string _transferControlsTitle = string.Empty;
+    [ObservableProperty] private string _transferControlsDescription = string.Empty;
 
     [ObservableProperty] private string _updateAvailableBadgeText = string.Empty;
     [ObservableProperty] private string _pausedBadgeText = string.Empty;
@@ -86,10 +96,11 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
     [ObservableProperty] private string _updateTypeText = string.Empty;
     [ObservableProperty] private bool _isUpdateAvailable;
     [ObservableProperty] private bool _isDeltaUpdate;
+    [ObservableProperty] private bool _forceReinstall;
 
     [ObservableProperty] private string _selectedUpdateChannelValue = UpdateSettingsValues.ChannelStable;
     [ObservableProperty] private string _selectedUpdateSourceValue = UpdateSettingsValues.DownloadSourcePdc;
-    [ObservableProperty] private string _selectedUpdateModeValue = UpdateSettingsValues.ModeDownloadThenConfirm;
+    [ObservableProperty] private string _selectedUpdateModeValue = UpdateSettingsValues.ModeSilentDownload;
     [ObservableProperty] private double _downloadThreadsSliderValue = UpdateSettingsValues.DefaultDownloadThreads;
 
     [ObservableProperty] private SelectionOption? _selectedChannel;
@@ -183,6 +194,16 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
         SavePreferenceState();
     }
 
+    partial void OnForceReinstallChanged(bool value)
+    {
+        SavePreferenceState();
+        UpdateTypeText = value
+            ? L("settings.update.type_reinstall", "Reinstall")
+            : (IsDeltaUpdate
+                ? L("settings.update.type_delta", "Incremental Update")
+                : UpdateTypeText);
+    }
+
     [RelayCommand(CanExecute = nameof(CanCheck))]
     private async Task CheckAsync()
     {
@@ -332,6 +353,7 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
         SelectedUpdateSourceValue = state.UpdateDownloadSource;
         SelectedUpdateModeValue = state.UpdateMode;
         DownloadThreadsSliderValue = UpdateSettingsValues.NormalizeDownloadThreads(state.UpdateDownloadThreads);
+        ForceReinstall = state.ForceUpdateReinstall;
 
         SyncComboBoxSelections();
     }
@@ -369,9 +391,19 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
         LastCheckedLabel = L("settings.update.last_checked_label", "Last Checked");
         UpdateTypeLabel = L("settings.update.update_type_label", "Update Type");
         ChannelLabel = L("settings.update.channel_label", "Update Channel");
+        ChannelDescription = L("settings.update.channel_description", "Choose Stable for regular releases or Preview for earlier builds.");
         SourceLabel = L("settings.update.source_label", "Download Source");
+        SourceDescription = L("settings.update.source_description", "Select the manifest and installer source used by the update workflow.");
         ModeLabel = L("settings.update.mode_label", "Update Mode");
+        ModeDescription = L("settings.update.mode_description", "Manual never downloads or installs automatically. Silent Download downloads in the background. Silent Install downloads in the background and applies on exit.");
         DownloadThreadsLabel = L("settings.update.download_threads_label", "Download Threads");
+        DownloadThreadsDescription = L("settings.update.download_threads_description", "Select how many parallel threads are used for update downloads. Paused downloads can be resumed later.");
+        ForceReinstallLabel = L("settings.update.force_reinstall_label", "Force Reinstall");
+        ForceReinstallDescription = L("settings.update.force_reinstall_description", "Download the full payload for the selected version and mark this run as a reinstall instead of an incremental update.");
+        ResumeSupportLabel = L("settings.update.resume_support_label", "Resume Support");
+        ResumeSupportDescription = L("settings.update.resume_support_description", "Downloads keep partial files and package metadata, so Pause and Resume continue from the previous state when the server supports it.");
+        TransferControlsTitle = L("settings.update.transfer_controls_title", "Transfer Controls");
+        TransferControlsDescription = L("settings.update.transfer_controls_description", "Pause a running download, resume it from the saved state, or cancel and clear pending update artifacts.");
 
         UpdateAvailableBadgeText = L("settings.update.badge_available", "Update available");
         PausedBadgeText = L("settings.update.badge_paused", "Paused");
@@ -423,9 +455,9 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
     {
         return
         [
-            new(UpdateSettingsValues.ModeManual, L("settings.update.mode_manual", "Manual")),
-            new(UpdateSettingsValues.ModeDownloadThenConfirm, L("settings.update.mode_confirm", "Download then Confirm")),
-            new(UpdateSettingsValues.ModeSilentOnExit, L("settings.update.mode_silent", "Silent on Exit"))
+            new(UpdateSettingsValues.ModeManual, L("settings.update.mode_manual", "Manual: no automatic download or install")),
+            new(UpdateSettingsValues.ModeSilentDownload, L("settings.update.mode_silent_download", "Silent Download")),
+            new(UpdateSettingsValues.ModeSilentInstall, L("settings.update.mode_silent_install", "Silent Install"))
         ];
     }
 
@@ -437,7 +469,8 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
             UpdateChannel = SelectedUpdateChannelValue,
             UpdateDownloadSource = SelectedUpdateSourceValue,
             UpdateMode = SelectedUpdateModeValue,
-            UpdateDownloadThreads = UpdateSettingsValues.NormalizeDownloadThreads((int)Math.Round(DownloadThreadsSliderValue))
+            UpdateDownloadThreads = UpdateSettingsValues.NormalizeDownloadThreads((int)Math.Round(DownloadThreadsSliderValue)),
+            ForceUpdateReinstall = ForceReinstall
         });
     }
 
@@ -541,12 +574,19 @@ public sealed partial class UpdateSettingsViewModel : ViewModelBase, IDisposable
         => L("settings.update.status_canceled", "Update canceled.");
 
     private string GetUpdateTypeText(UpdatePayloadKind? payloadKind)
-        => payloadKind switch
+    {
+        if (ForceReinstall)
+        {
+            return L("settings.update.type_reinstall", "Reinstall");
+        }
+
+        return payloadKind switch
         {
             UpdatePayloadKind.DeltaPlonds or UpdatePayloadKind.DeltaLegacy => L("settings.update.type_delta", "Incremental Update"),
-            UpdatePayloadKind.FullInstaller => L("settings.update.type_full", "Full Installer"),
+            UpdatePayloadKind.FullInstaller => L("settings.update.type_reinstall", "Reinstall"),
             _ => string.Empty
         };
+    }
 
     private string L(string key, string fallback)
         => _localizationService.GetString(_languageCode, key, fallback);

LanMountainDesktop/Views/MainWindow.SettingsHardCut.Stubs.cs

@@ -96,6 +96,7 @@ public partial class MainWindow : Window
                 string.Equals(key, nameof(AppSettingsSnapshot.UpdateDownloadSource), StringComparison.OrdinalIgnoreCase) ||
                 string.Equals(key, nameof(AppSettingsSnapshot.UseGhProxyMirror), StringComparison.OrdinalIgnoreCase) ||
                 string.Equals(key, nameof(AppSettingsSnapshot.UpdateDownloadThreads), StringComparison.OrdinalIgnoreCase) ||
+                string.Equals(key, nameof(AppSettingsSnapshot.ForceUpdateReinstall), StringComparison.OrdinalIgnoreCase) ||
                 string.Equals(key, nameof(AppSettingsSnapshot.EnableThreeFingerSwipe), StringComparison.OrdinalIgnoreCase) ||
                 string.Equals(key, nameof(AppSettingsSnapshot.EnableFadeTransition), StringComparison.OrdinalIgnoreCase) ||
                 string.Equals(key, nameof(AppSettingsSnapshot.ShowInTaskbar), StringComparison.OrdinalIgnoreCase) ||
@@ -681,6 +682,7 @@ public partial class MainWindow : Window
             UpdateMode = latestUpdateState.UpdateMode,
             UpdateDownloadSource = latestUpdateState.UpdateDownloadSource,
             UpdateDownloadThreads = latestUpdateState.UpdateDownloadThreads,
+            ForceUpdateReinstall = latestUpdateState.ForceUpdateReinstall,
             UseGhProxyMirror = latestUpdateState.UseGhProxyMirror,
             PendingUpdateInstallerPath = latestUpdateState.PendingUpdateInstallerPath,
             PendingUpdateVersion = latestUpdateState.PendingUpdateVersion,

LanMountainDesktop/Views/SettingsPages/DevSettingsPage.axaml

@@ -44,7 +44,21 @@
                     <ui:FAFontIconSource Glyph="&#xF01A8;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
                 </ui:FASettingsExpander.IconSource>
                 <ui:FASettingsExpander.Footer>
-                    <ToggleSwitch IsChecked="{Binding EnableFusedDesktop}" />
+                    <ToggleSwitch x:Name="FusedDesktopToggle"
+                                  IsChecked="{Binding EnableFusedDesktop, Mode=OneWay}"
+                                  IsCheckedChanged="OnFusedDesktopToggleChanged" />
+                </ui:FASettingsExpander.Footer>
+            </ui:FASettingsExpander>
+
+            <ui:FASettingsExpander Header="{Binding MainWindowDesktopLayerHeader}"
+                                 Description="{Binding MainWindowDesktopLayerDescription}">
+                <ui:FASettingsExpander.IconSource>
+                    <ui:FAFontIconSource Glyph="&#xF1BE0;" FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
+                </ui:FASettingsExpander.IconSource>
+                <ui:FASettingsExpander.Footer>
+                    <ToggleSwitch x:Name="MainWindowDesktopLayerToggle"
+                                  IsChecked="{Binding EnableMainWindowDesktopLayer, Mode=OneWay}"
+                                  IsCheckedChanged="OnMainWindowDesktopLayerToggleChanged" />
                 </ui:FASettingsExpander.Footer>
             </ui:FASettingsExpander>
 

LanMountainDesktop/Views/SettingsPages/DevSettingsPage.axaml.cs

@@ -1,3 +1,7 @@
+using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.VisualTree;
+using FluentAvalonia.UI.Controls;
 using LanMountainDesktop.PluginSdk;
 using LanMountainDesktop.Services.Settings;
 using LanMountainDesktop.ViewModels;
@@ -14,6 +18,9 @@ namespace LanMountainDesktop.Views.SettingsPages;
     DescriptionLocalizationKey = "settings.dev.description")]
 public partial class DevSettingsPage : SettingsPageBase
 {
+    private bool _isReady;
+    private bool _syncingToggles;
+
     public DevSettingsPage()
         : this(new DevSettingsPageViewModel(HostSettingsFacadeProvider.GetOrCreate()))
     {
@@ -24,7 +31,92 @@ public partial class DevSettingsPage : SettingsPageBase
         ViewModel = viewModel;
         DataContext = ViewModel;
         InitializeComponent();
+        _isReady = true;
     }
 
     public DevSettingsPageViewModel ViewModel { get; }
+
+    private async void OnFusedDesktopToggleChanged(object? sender, RoutedEventArgs e)
+    {
+        if (!_isReady || _syncingToggles || sender is not ToggleSwitch toggle)
+        {
+            return;
+        }
+
+        var requested = toggle.IsChecked == true;
+        if (!requested)
+        {
+            ViewModel.ApplyFusedDesktopPreference(enabled: false, disableMainWindowDesktopLayer: false);
+            SyncTogglesFromViewModel();
+            return;
+        }
+
+        if (ViewModel.EnableMainWindowDesktopLayer &&
+            !await ConfirmDesktopLayerSwitchAsync(ViewModel.DesktopLayerConflictEnableFusedMessage).ConfigureAwait(true))
+        {
+            SyncTogglesFromViewModel();
+            return;
+        }
+
+        ViewModel.ApplyFusedDesktopPreference(enabled: true, disableMainWindowDesktopLayer: true);
+        SyncTogglesFromViewModel();
+    }
+
+    private async void OnMainWindowDesktopLayerToggleChanged(object? sender, RoutedEventArgs e)
+    {
+        if (!_isReady || _syncingToggles || sender is not ToggleSwitch toggle)
+        {
+            return;
+        }
+
+        var requested = toggle.IsChecked == true;
+        if (!requested)
+        {
+            ViewModel.ApplyMainWindowDesktopLayerPreference(enabled: false, disableFusedDesktop: false);
+            SyncTogglesFromViewModel();
+            return;
+        }
+
+        if (ViewModel.EnableFusedDesktop &&
+            !await ConfirmDesktopLayerSwitchAsync(ViewModel.DesktopLayerConflictEnableMainMessage).ConfigureAwait(true))
+        {
+            SyncTogglesFromViewModel();
+            return;
+        }
+
+        ViewModel.ApplyMainWindowDesktopLayerPreference(enabled: true, disableFusedDesktop: true);
+        SyncTogglesFromViewModel();
+    }
+
+    private async Task<bool> ConfirmDesktopLayerSwitchAsync(string message)
+    {
+        var dialog = new FAContentDialog
+        {
+            Title = ViewModel.DesktopLayerConflictTitle,
+            Content = message,
+            PrimaryButtonText = ViewModel.DesktopLayerConflictConfirmText,
+            CloseButtonText = ViewModel.DesktopLayerConflictCancelText,
+            DefaultButton = FAContentDialogButton.Close
+        };
+
+        var owner = this.FindAncestorOfType<Window>();
+        var result = owner is not null
+            ? await dialog.ShowAsync(owner)
+            : await dialog.ShowAsync();
+        return result == FAContentDialogResult.Primary;
+    }
+
+    private void SyncTogglesFromViewModel()
+    {
+        _syncingToggles = true;
+        try
+        {
+            FusedDesktopToggle.IsChecked = ViewModel.EnableFusedDesktop;
+            MainWindowDesktopLayerToggle.IsChecked = ViewModel.EnableMainWindowDesktopLayer;
+        }
+        finally
+        {
+            _syncingToggles = false;
+        }
+    }
 }

LanMountainDesktop/Views/SettingsPages/UpdateSettingsPage.axaml

@@ -89,49 +89,40 @@
               </ui:FAInfoBar.IconSource>
             </ui:FAInfoBar>
 
+            <ui:FAInfoBar Title="{Binding ResumeSupportLabel}"
+                          Message="{Binding ResumeSupportDescription}"
+                          IsOpen="True"
+                          IsClosable="False"
+                          Severity="Informational">
+              <ui:FAInfoBar.IconSource>
+                <ui:FAFontIconSource Glyph="&#xF0647;"
+                                     FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
+              </ui:FAInfoBar.IconSource>
+            </ui:FAInfoBar>
+
             <StackPanel Orientation="Horizontal"
-                        Spacing="8"
-                        IsVisible="{Binding CanDownload}">
+                        Spacing="8">
               <Button Classes="settings-accent-button"
                       Content="{Binding DownloadButtonText}"
-                      Command="{Binding DownloadCommand}" />
-            </StackPanel>
-
-            <StackPanel Orientation="Horizontal"
-                        Spacing="8"
-                        IsVisible="{Binding CanInstall}">
+                      Command="{Binding DownloadCommand}"
+                      IsVisible="{Binding CanDownload}" />
               <Button Classes="settings-accent-button"
                       Content="{Binding InstallButtonText}"
-                      Command="{Binding InstallCommand}" />
-            </StackPanel>
-
-            <StackPanel Orientation="Horizontal"
-                        Spacing="8"
-                        IsVisible="{Binding CanPause}">
+                      Command="{Binding InstallCommand}"
+                      IsVisible="{Binding CanInstall}" />
               <Button Content="{Binding PauseButtonText}"
-                      Command="{Binding PauseCommand}" />
-            </StackPanel>
-
-            <StackPanel Orientation="Horizontal"
-                        Spacing="8"
-                        IsVisible="{Binding CanResume}">
+                      Command="{Binding PauseCommand}"
+                      IsVisible="{Binding CanPause}" />
               <Button Classes="settings-accent-button"
                       Content="{Binding ResumeButtonText}"
-                      Command="{Binding ResumeCommand}" />
-            </StackPanel>
-
-            <StackPanel Orientation="Horizontal"
-                        Spacing="8"
-                        IsVisible="{Binding CanRollback}">
+                      Command="{Binding ResumeCommand}"
+                      IsVisible="{Binding CanResume}" />
               <Button Content="{Binding RollbackButtonText}"
-                      Command="{Binding RollbackCommand}" />
-            </StackPanel>
-
-            <StackPanel Orientation="Horizontal"
-                        Spacing="8"
-                        IsVisible="{Binding CanCancel}">
+                      Command="{Binding RollbackCommand}"
+                      IsVisible="{Binding CanRollback}" />
               <Button Content="{Binding CancelButtonText}"
-                      Command="{Binding CancelCommand}" />
+                      Command="{Binding CancelCommand}"
+                      IsVisible="{Binding CanCancel}" />
             </StackPanel>
           </StackPanel>
         </ui:FASettingsExpanderItem>
@@ -211,7 +202,8 @@
           <ui:FAFontIconSource Glyph="&#xF0504;"
                                FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
         </ui:FASettingsExpander.IconSource>
-        <ui:FASettingsExpanderItem Content="{Binding ChannelLabel}">
+        <ui:FASettingsExpanderItem Content="{Binding ChannelLabel}"
+                                   Description="{Binding ChannelDescription}">
           <ui:FASettingsExpanderItem.IconSource>
             <ui:FAFontIconSource Glyph="&#xF0908;"
                                  FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
@@ -219,11 +211,17 @@
           <ui:FASettingsExpanderItem.Footer>
             <ComboBox Width="220"
                       ItemsSource="{Binding ChannelOptions}"
-                      SelectedItem="{Binding SelectedChannel}"
-                      DisplayMemberBinding="{Binding Label}" />
+                      SelectedItem="{Binding SelectedChannel}">
+              <ComboBox.ItemTemplate>
+                <DataTemplate x:DataType="vm:SelectionOption">
+                  <TextBlock Text="{Binding Label}" />
+                </DataTemplate>
+              </ComboBox.ItemTemplate>
+            </ComboBox>
           </ui:FASettingsExpanderItem.Footer>
         </ui:FASettingsExpanderItem>
-        <ui:FASettingsExpanderItem Content="{Binding SourceLabel}">
+        <ui:FASettingsExpanderItem Content="{Binding SourceLabel}"
+                                   Description="{Binding SourceDescription}">
           <ui:FASettingsExpanderItem.IconSource>
             <ui:FAFontIconSource Glyph="&#xF0B4E;"
                                  FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
@@ -231,11 +229,17 @@
           <ui:FASettingsExpanderItem.Footer>
             <ComboBox Width="220"
                       ItemsSource="{Binding SourceOptions}"
-                      SelectedItem="{Binding SelectedSource}"
-                      DisplayMemberBinding="{Binding Label}" />
+                      SelectedItem="{Binding SelectedSource}">
+              <ComboBox.ItemTemplate>
+                <DataTemplate x:DataType="vm:SelectionOption">
+                  <TextBlock Text="{Binding Label}" />
+                </DataTemplate>
+              </ComboBox.ItemTemplate>
+            </ComboBox>
           </ui:FASettingsExpanderItem.Footer>
         </ui:FASettingsExpanderItem>
-        <ui:FASettingsExpanderItem Content="{Binding ModeLabel}">
+        <ui:FASettingsExpanderItem Content="{Binding ModeLabel}"
+                                   Description="{Binding ModeDescription}">
           <ui:FASettingsExpanderItem.IconSource>
             <ui:FAFontIconSource Glyph="&#xF08E8;"
                                  FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
@@ -243,11 +247,28 @@
           <ui:FASettingsExpanderItem.Footer>
             <ComboBox Width="220"
                       ItemsSource="{Binding ModeOptions}"
-                      SelectedItem="{Binding SelectedMode}"
-                      DisplayMemberBinding="{Binding Label}" />
+                      SelectedItem="{Binding SelectedMode}">
+              <ComboBox.ItemTemplate>
+                <DataTemplate x:DataType="vm:SelectionOption">
+                  <TextBlock Text="{Binding Label}"
+                             TextWrapping="Wrap" />
+                </DataTemplate>
+              </ComboBox.ItemTemplate>
+            </ComboBox>
           </ui:FASettingsExpanderItem.Footer>
         </ui:FASettingsExpanderItem>
-        <ui:FASettingsExpanderItem Content="{Binding DownloadThreadsLabel}">
+        <ui:FASettingsExpanderItem Content="{Binding ForceReinstallLabel}"
+                                   Description="{Binding ForceReinstallDescription}">
+          <ui:FASettingsExpanderItem.IconSource>
+            <ui:FAFontIconSource Glyph="&#xF0504;"
+                                 FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
+          </ui:FASettingsExpanderItem.IconSource>
+          <ui:FASettingsExpanderItem.Footer>
+            <ToggleSwitch IsChecked="{Binding ForceReinstall}" />
+          </ui:FASettingsExpanderItem.Footer>
+        </ui:FASettingsExpanderItem>
+        <ui:FASettingsExpanderItem Content="{Binding DownloadThreadsLabel}"
+                                   Description="{Binding DownloadThreadsDescription}">
           <ui:FASettingsExpanderItem.IconSource>
             <ui:FAFontIconSource Glyph="&#xF0168;"
                                  FontFamily="avares://fluenticons.resources.avalonia/Assets#Seagull Fluent Icons" />
@@ -258,7 +279,7 @@
                         VerticalAlignment="Center">
               <Slider Width="140"
                       Minimum="1"
-                      Maximum="16"
+                      Maximum="128"
                       Value="{Binding DownloadThreadsSliderValue}"
                       TickFrequency="1"
                       IsSnapToTickEnabled="True" />

docs/ARCHITECTURE.md

@@ -245,6 +245,15 @@ See `docs/EXTERNAL_IPC_ARCHITECTURE.md` for the detailed contract and migration
 - On Windows, desktop-surface windows may attach to the desktop icon host through `IWindowBottomMostService`, or fall back to `HWND_BOTTOM`.
 - Fused desktop windows refresh their bottom-most layer after being opened, shown, or reloaded so they do not cover ordinary apps.
 
+## Main Window Desktop Layer
+
+- The main desktop host window has a separate developer option, `EnableMainWindowDesktopLayer`.
+- This mode is mutually exclusive with fused desktop because fused desktop manages component windows while main-window desktop layer manages the host window itself.
+- The main-window service is `IMainWindowDesktopLayerService`; it attaches only the main window to the desktop icon host on Windows and falls back to `HWND_BOTTOM`.
+- The main-window service does not use fused desktop click-through region logic, so the main desktop window remains interactive.
+- Main-window restore paths refresh the desktop-layer attachment instead of using temporary `Topmost` foreground promotion while this mode is enabled.
+- Air APP windows remain ordinary application windows and are not handled by either desktop-layer service.
+
 ## Air APP Window Chrome
 
 - `LanMountainDesktop.AirAppHost` owns Air APP window chrome through `AirAppWindowDescriptor`.

scripts/analyze_commits.ps1

@@ -0,0 +1,144 @@
+# Analyze Git commits from today and generate Markdown reports
+
+param(
+    [string]$RepoPath = (Split-Path -Parent $PSScriptRoot)
+)
+
+Write-Host "Analyzing repository: $RepoPath"
+
+# Create output directory
+$outputDir = Join-Path (Join-Path $RepoPath "docs") "auto_commit_md"
+if (-not (Test-Path $outputDir)) {
+    New-Item -ItemType Directory -Path $outputDir -Force | Out-Null
+    Write-Host "Created directory: $outputDir"
+} else {
+    Write-Host "Output directory: $outputDir"
+}
+
+Write-Host ""
+
+# Get today's date range
+$today = Get-Date
+$todayStart = $today.Date.ToString("yyyy-MM-ddTHH:mm:ss")
+$todayEnd = $today.Date.AddDays(1).AddSeconds(-1).ToString("yyyy-MM-ddTHH:mm:ss")
+
+# Get commits from today
+$commitsOutput = & git -C $RepoPath log --since="$todayStart" --until="$todayEnd" --pretty=format:"%H|%an|%ae|%ad|%s" --date=iso
+
+if (-not $commitsOutput) {
+    Write-Host "No new commits today."
+    exit 0
+}
+
+$commits = @()
+foreach ($line in $commitsOutput -split "`n") {
+    if (-not $line) { continue }
+    $parts = $line -split '\|', 5
+    if ($parts.Count -eq 5) {
+        $commits += @{
+            Hash = $parts[0]
+            AuthorName = $parts[1]
+            AuthorEmail = $parts[2]
+            Date = $parts[3]
+            Message = $parts[4]
+        }
+    }
+}
+
+Write-Host "Found $($commits.Count) commits today."
+Write-Host ""
+
+foreach ($commit in $commits) {
+    $shortHash = $commit.Hash.Substring(0, 7)
+    Write-Host "Processing commit: $shortHash - $($commit.Message)"
+
+    # Get commit details
+    $diffStat = & git -C $RepoPath show --stat $commit.Hash
+    $diffDetails = & git -C $RepoPath show $commit.Hash
+
+    # Parse statistics
+    $filesChanged = @()
+    $totalInsertions = 0
+    $totalDeletions = 0
+
+    foreach ($line in $diffStat -split "`n") {
+        if ($line -match '(\d+) insertion') {
+            $totalInsertions += [int]$matches[1]
+        }
+        if ($line -match '(\d+) deletion') {
+            $totalDeletions += [int]$matches[1]
+        }
+        if ($line -match '^\s*(.*?)\s*\|\s*(\d+)') {
+            $filesChanged += @{
+                File = $matches[1]
+                Lines = [int]$matches[2]
+            }
+        }
+    }
+
+    # Generate filename
+    $dateStr = $commit.Date.Split(' ')[0].Replace('-', '')
+    $filename = "$dateStr`_$shortHash.md"
+    $outputPath = Join-Path $outputDir $filename
+
+    # Generate Markdown content
+    $report = @"
+# Commit Analysis Report - $shortHash
+
+## Basic Information
+
+| Item | Content |
+|------|---------|
+| Commit Hash | `` $($commit.Hash) `` |
+| Author | $($commit.AuthorName) ($($commit.AuthorEmail)) |
+| Commit Time | $($commit.Date) |
+
+## Commit Message
+
+$($commit.Message)
+
+## Change Statistics
+
+| Metric | Value |
+|--------|-------|
+| Files Changed | $($filesChanged.Count) |
+| Lines Added | +$totalInsertions |
+| Lines Removed | -$totalDeletions |
+
+## Modified Files
+
+"@
+
+    foreach ($file in $filesChanged) {
+        $report += "- $($file.File) ($($file.Lines) lines)`n"
+    }
+
+    $report += @"
+
+## Detailed Changes
+
+```diff
+$diffDetails
+```
+
+## Code Review Checklist
+
+> This section is auto-generated, manual review recommended
+
+- [ ] Check for potential bugs
+- [ ] Verify code follows project standards
+- [ ] Test new functionality if applicable
+- [ ] Check for security issues
+
+---
+
+*Report generated: $(Get-Date -Format "yyyy-MM-dd HH:mm:ss")*
+"@
+
+    # Save file
+    [System.IO.File]::WriteAllText($outputPath, $report, [System.Text.Encoding]::UTF8)
+    Write-Host "  Report saved: $outputPath"
+}
+
+Write-Host ""
+Write-Host "Done!"

scripts/analyze_commits.py

@@ -0,0 +1,206 @@
+#!/usr/bin/env python3
+"""
+分析当天 Git 提交并生成 Markdown 报告的脚本
+"""
+
+import os
+import subprocess
+import sys
+from datetime import datetime
+import re
+
+
+def run_command(cmd, cwd=None):
+    """运行命令并返回输出"""
+    try:
+        result = subprocess.run(
+            cmd,
+            shell=True,
+            capture_output=True,
+            text=True,
+            cwd=cwd,
+            encoding='utf-8',
+            errors='replace'
+        )
+        return result.stdout, result.stderr, result.returncode
+    except Exception as e:
+        return "", str(e), 1
+
+
+def get_today_commits(repo_path):
+    """获取当天的所有提交"""
+    today_start = datetime.now().strftime('%Y-%m-%dT00:00:00')
+    today_end = datetime.now().strftime('%Y-%m-%dT23:59:59')
+    
+    cmd = f'git log --since="{today_start}" --until="{today_end}" --pretty=format:"%H|%an|%ae|%ad|%s" --date=iso'
+    stdout, stderr, code = run_command(cmd, cwd=repo_path)
+    
+    if code != 0:
+        print(f"Error getting commits: {stderr}")
+        return []
+    
+    commits = []
+    for line in stdout.strip().split('\n'):
+        if not line:
+            continue
+        parts = line.split('|', 4)
+        if len(parts) == 5:
+            commits.append({
+                'hash': parts[0],
+                'author_name': parts[1],
+                'author_email': parts[2],
+                'date': parts[3],
+                'message': parts[4]
+            })
+    return commits
+
+
+def get_commit_diff(repo_path, commit_hash):
+    """获取提交的详细 diff"""
+    cmd = f'git show --stat {commit_hash}'
+    stdout, _, _ = run_command(cmd, cwd=repo_path)
+    return stdout
+
+
+def get_commit_details(repo_path, commit_hash):
+    """获取提交的详细信息"""
+    cmd = f'git show {commit_hash}'
+    stdout, _, _ = run_command(cmd, cwd=repo_path)
+    return stdout
+
+
+def parse_diff_stats(diff_stat):
+    """解析 diff --stat 的输出"""
+    files_changed = []
+    total_insertions = 0
+    total_deletions = 0
+    
+    lines = diff_stat.strip().split('\n')
+    for line in lines:
+        match = re.search(r'(\d+) insertion', line)
+        if match:
+            total_insertions += int(match.group(1))
+        match = re.search(r'(\d+) deletion', line)
+        if match:
+            total_deletions += int(match.group(1))
+        
+        file_match = re.match(r'^\s*(.*?)\s*\|\s*(\d+)', line)
+        if file_match:
+            files_changed.append({
+                'file': file_match.group(1),
+                'lines': int(file_match.group(2))
+            })
+    
+    return {
+        'files': files_changed,
+        'insertions': total_insertions,
+        'deletions': total_deletions
+    }
+
+
+def generate_markdown_report(commit, diff_stat, diff_details):
+    """生成 Markdown 报告"""
+    short_hash = commit['hash'][:7]
+    date_str = commit['date'].split(' ')[0].replace('-', '')
+    
+    report = f"""# 提交分析报告 - {short_hash}
+
+## 基本信息
+
+| 项目 | 内容 |
+|------|------|
+| 提交哈希 | `{commit['hash']}` |
+| 作者 | {commit['author_name']} ({commit['author_email']}) |
+| 提交时间 | {commit['date']} |
+
+## 提交信息
+
+{commit['message']}
+
+## 变更统计
+
+| 指标 | 数值 |
+|------|------|
+| 修改文件数 | {len(diff_stat['files'])} |
+| 新增行数 | +{diff_stat['insertions']} |
+| 删除行数 | -{diff_stat['deletions']} |
+
+## 修改文件列表
+
+"""
+    
+    for file_info in diff_stat['files']:
+        report += f"- {file_info['file']} ({file_info['lines']} 行)\n"
+    
+    report += f"""
+## 详细变更
+
+```diff
+{diff_details}
+```
+
+## 代码审查要点
+
+> 此部分为自动生成，建议人工审查确认
+
+- [ ] 检查是否有潜在的 bug
+- [ ] 确认代码符合项目规范
+- [ ] 验证是否有需要测试的新功能
+- [ ] 检查是否有安全问题
+
+---
+
+*报告生成时间: {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}*
+"""
+    
+    return report, f"{date_str}_{short_hash}.md"
+
+
+def main():
+    repo_path = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+    output_dir = os.path.join(repo_path, 'docs', 'auto_commit_md')
+    
+    # 创建输出目录
+    os.makedirs(output_dir, exist_ok=True)
+    
+    print(f"分析仓库: {repo_path}")
+    print(f"输出目录: {output_dir}")
+    print()
+    
+    # 获取当天的提交
+    commits = get_today_commits(repo_path)
+    
+    if not commits:
+        print("今天没有新提交。")
+        return 0
+    
+    print(f"找到 {len(commits)} 个今天的提交。")
+    print()
+    
+    for commit in commits:
+        print(f"处理提交: {commit['hash'][:7]} - {commit['message']}")
+        
+        # 获取提交详情
+        diff_stat = get_commit_diff(repo_path, commit['hash'])
+        diff_details = get_commit_details(repo_path, commit['hash'])
+        
+        # 解析统计信息
+        stats = parse_diff_stats(diff_stat)
+        
+        # 生成报告
+        report_content, filename = generate_markdown_report(commit, stats, diff_details)
+        
+        # 保存文件
+        output_path = os.path.join(output_dir, filename)
+        with open(output_path, 'w', encoding='utf-8') as f:
+            f.write(report_content)
+        
+        print(f"  报告已保存: {output_path}")
+    
+    print()
+    print("完成！")
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())

scripts/generate_commit_reports.py

@@ -0,0 +1,177 @@
+#!/usr/bin/env python3
+import subprocess
+import os
+import re
+from datetime import datetime
+from pathlib import Path
+
+
+def run_git_command(cmd, cwd=None):
+    result = subprocess.run(cmd, shell=True, capture_output=True, text=True, cwd=cwd)
+    if result.returncode != 0:
+        print(f"Git command failed: {cmd}")
+        print(f"Error: {result.stderr}")
+        return None
+    return result.stdout
+
+
+def get_commits_since(since_date, until_date, cwd=None):
+    cmd = f'git log --since="{since_date}" --until="{until_date}" --pretty=format:"%H|%an|%ae|%ad|%s" --date=iso'
+    output = run_git_command(cmd, cwd)
+    if not output:
+        return []
+    commits = []
+    for line in output.strip().split('\n'):
+        if line:
+            parts = line.split('|', 4)
+            commits.append({
+                'hash': parts[0],
+                'author': parts[1],
+                'email': parts[2],
+                'date': parts[3],
+                'message': parts[4]
+            })
+    return commits
+
+
+def get_commit_diff(commit_hash, cwd=None):
+    cmd = f'git show {commit_hash}'
+    return run_git_command(cmd, cwd)
+
+
+def get_commit_stat(commit_hash, cwd=None):
+    cmd = f'git show --stat {commit_hash}'
+    return run_git_command(cmd, cwd)
+
+
+def analyze_diff(diff_text):
+    file_changes = []
+    current_file = None
+    changes = {'insertions': 0, 'deletions': 0, 'files': 0}
+    
+    lines = diff_text.split('\n')
+    for line in lines:
+        if line.startswith('diff --git'):
+            if current_file:
+                file_changes.append(current_file)
+            filename = line.split(' ')[2][2:]
+            current_file = {'name': filename, 'insertions': 0, 'deletions': 0, 'hunks': []}
+            changes['files'] += 1
+        elif line.startswith('+') and not line.startswith('+++'):
+            if current_file:
+                current_file['insertions'] += 1
+                changes['insertions'] += 1
+        elif line.startswith('-') and not line.startswith('---'):
+            if current_file:
+                current_file['deletions'] += 1
+                changes['deletions'] += 1
+    
+    if current_file:
+        file_changes.append(current_file)
+    
+    return file_changes, changes
+
+
+def generate_markdown_report(commit, diff_text, stat_text, output_dir):
+    file_changes, summary = analyze_diff(diff_text)
+    
+    short_hash = commit['hash'][:7]
+    date_obj = datetime.fromisoformat(commit['date'].replace(' +0800', ''))
+    date_str = date_obj.strftime('%Y%m%d')
+    
+    filename = f"{date_str}_{short_hash}.md"
+    filepath = Path(output_dir) / filename
+    
+    markdown = f"""# Git 提交分析报告
+
+## 基本信息
+
+| 项目 | 内容 |
+|------|------|
+| 提交哈希 | `{commit['hash']}` |
+| 短哈希 | `{short_hash}` |
+| 作者 | {commit['author']} <{commit['email']}> |
+| 提交时间 | {commit['date']} |
+
+## 提交信息
+
+{commit['message']}
+
+## 变更统计
+
+- **变更文件数**: {summary['files']}
+- **新增行数**: +{summary['insertions']}
+- **删除行数**: -{summary['deletions']}
+
+## 详细变更
+
+"""
+
+    if file_changes:
+        for fc in sorted(file_changes, key=lambda x: x['name']):
+            markdown += f"\n### `{fc['name']}`\n"
+            markdown += f"- 新增: +{fc['insertions']} 行\n"
+            markdown += f"- 删除: -{fc['deletions']} 行\n"
+    else:
+        markdown += "\n*无文件变更统计*\n"
+
+    markdown += "\n## 完整 Diff\n\n```diff\n"
+    markdown += diff_text
+    markdown += "\n```\n"
+
+    with open(filepath, 'w', encoding='utf-8') as f:
+        f.write(markdown)
+    
+    print(f"Generated: {filepath}")
+    return filepath
+
+
+def main():
+    repo_dir = Path(__file__).parent.parent
+    output_dir = repo_dir / 'docs' / 'auto_commit_md'
+    output_dir.mkdir(parents=True, exist_ok=True)
+    
+    today = datetime.now()
+    since_date = today.strftime('%Y-%m-%d 00:00:00')
+    until_date = today.strftime('%Y-%m-%d 23:59:59')
+    
+    print(f"Fetching commits from {since_date} to {until_date}...")
+    commits = get_commits_since(since_date, until_date, str(repo_dir))
+    
+    if not commits:
+        print("No commits found for today.")
+        print("\nLet's check the latest commits instead...")
+        cmd = 'git log -3 --pretty=format:"%H|%an|%ae|%ad|%s" --date=iso'
+        output = run_git_command(cmd, str(repo_dir))
+        if output:
+            commits = []
+            for line in output.strip().split('\n'):
+                if line:
+                    parts = line.split('|', 4)
+                    commits.append({
+                        'hash': parts[0],
+                        'author': parts[1],
+                        'email': parts[2],
+                        'date': parts[3],
+                        'message': parts[4]
+                    })
+    
+    if commits:
+        print(f"\nFound {len(commits)} commit(s) to analyze:\n")
+        for commit in commits:
+            print(f"  - {commit['hash'][:7]}: {commit['message']}")
+        
+        print("\nGenerating reports...\n")
+        for commit in commits:
+            diff = get_commit_diff(commit['hash'], str(repo_dir))
+            stat = get_commit_stat(commit['hash'], str(repo_dir))
+            if diff:
+                generate_markdown_report(commit, diff, stat, str(output_dir))
+        
+        print(f"\nDone! Reports saved to {output_dir}")
+    else:
+        print("No commits found.")
+
+
+if __name__ == '__main__':
+    main()