Phase 5: tray icon with minimize-to-tray and context menu

GUI csproj enables UseWindowsForms (NotifyIcon lives in WinForms even
in .NET 8). New Services/TrayIcon.cs wraps NotifyIcon with a context
menu (Open / Restart service / Exit) and the embedded webhook-server
icon. MainWindow creates the TrayIcon, hides itself on minimize and
restores on tray double-click.

Adds GlobalUsings.cs to alias the WPF defaults for types that exist
in both WPF and WinForms (Application, MessageBox, TextBox, Binding,
etc.) so existing code keeps compiling without per-file changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/WebhookServer.Gui/App.xaml.cs

@@ -1,13 +1,5 @@
-using System.Configuration;
-using System.Data;
-using System.Windows;
-
 namespace WebhookServer.Gui;
 
-/// <summary>
-/// Interaction logic for App.xaml
-/// </summary>
 public partial class App : Application
 {
 }
-

src/WebhookServer.Gui/Converters/Converters.cs

@@ -1,6 +1,7 @@
 using System.Globalization;
 using System.Windows.Data;
-using System.Windows.Media;
+using Brush = System.Windows.Media.Brush;
+using Brushes = System.Windows.Media.Brushes;
 
 namespace WebhookServer.Gui.Converters;
 

src/WebhookServer.Gui/GlobalUsings.cs

@@ -0,0 +1,15 @@
+// Enabling UseWindowsForms (for the system tray NotifyIcon) brings the WinForms
+// namespace into scope, which conflicts with WPF for several common type names.
+// Alias the most-used types to their WPF variants project-wide so existing code
+// keeps compiling. Files that genuinely need a WinForms type import it explicitly
+// (System.Windows.Forms.NotifyIcon etc. in Services/TrayIcon.cs).
+
+global using Application = System.Windows.Application;
+global using MessageBox = System.Windows.MessageBox;
+global using Clipboard = System.Windows.Clipboard;
+global using TextBox = System.Windows.Controls.TextBox;
+global using RadioButton = System.Windows.Controls.RadioButton;
+global using MessageBoxButton = System.Windows.MessageBoxButton;
+global using MessageBoxImage = System.Windows.MessageBoxImage;
+global using MessageBoxResult = System.Windows.MessageBoxResult;
+global using Binding = System.Windows.Data.Binding;

src/WebhookServer.Gui/MainWindow.xaml.cs

@@ -8,12 +8,37 @@ namespace WebhookServer.Gui;
 
 public partial class MainWindow : Window
 {
+    private readonly TrayIcon _tray;
+    private readonly MainViewModel _vm;
+
     public MainWindow()
     {
         InitializeComponent();
-        var vm = new MainViewModel(new AdminPipeClient());
-        DataContext = vm;
-        Loaded += async (_, _) => await vm.RefreshCommand.ExecuteAsync(null);
+        _vm = new MainViewModel(new AdminPipeClient());
+        DataContext = _vm;
+
+        _tray = new TrayIcon(
+            resolveMainWindow: () => Application.Current.MainWindow,
+            restartServiceAsync: async () => await new AdminPipeClient().RestartListenerAsync());
+
+        Loaded += async (_, _) => await _vm.RefreshCommand.ExecuteAsync(null);
+        StateChanged += OnStateChanged;
+        Closed += (_, _) => _tray.Dispose();
+    }
+
+    private void OnStateChanged(object? sender, EventArgs e)
+    {
+        // Minimize-to-tray: hide the window when the user minimizes; restoring is
+        // via the tray icon's double-click or context menu.
+        if (WindowState == WindowState.Minimized)
+        {
+            Hide();
+            ShowInTaskbar = false;
+        }
+        else
+        {
+            ShowInTaskbar = true;
+        }
     }
 
     private void OnLogTailChanged(object sender, TextChangedEventArgs e)

src/WebhookServer.Gui/Services/TrayIcon.cs

@@ -0,0 +1,86 @@
+using System.Drawing;
+using System.Runtime.Versioning;
+using System.Windows;
+using System.Windows.Forms;
+
+namespace WebhookServer.Gui.Services;
+
+/// <summary>
+/// Minimal system tray icon using Windows Forms NotifyIcon. Owns a context menu
+/// (Open / Restart service / Exit) and toggles the main window visibility on
+/// double-click. Hide-to-tray on minimize is wired in MainWindow.xaml.cs.
+/// </summary>
+[SupportedOSPlatform("windows")]
+public sealed class TrayIcon : IDisposable
+{
+    private readonly NotifyIcon _icon;
+    private readonly Func<Window?> _resolveMainWindow;
+    private readonly Func<Task> _restartServiceAsync;
+
+    public TrayIcon(Func<Window?> resolveMainWindow, Func<Task> restartServiceAsync)
+    {
+        _resolveMainWindow = resolveMainWindow;
+        _restartServiceAsync = restartServiceAsync;
+
+        _icon = new NotifyIcon
+        {
+            Icon = LoadEmbeddedIcon(),
+            Text = "Webhook Server",
+            Visible = true,
+        };
+        _icon.DoubleClick += (_, _) => ShowMainWindow();
+        _icon.ContextMenuStrip = BuildMenu();
+    }
+
+    private ContextMenuStrip BuildMenu()
+    {
+        var menu = new ContextMenuStrip();
+        menu.Items.Add("&Open Webhook Server", null, (_, _) => ShowMainWindow());
+        menu.Items.Add(new ToolStripSeparator());
+        menu.Items.Add("&Restart service", null, async (_, _) => await _restartServiceAsync().ConfigureAwait(false));
+        menu.Items.Add(new ToolStripSeparator());
+        menu.Items.Add("E&xit", null, (_, _) => Application.Current.Shutdown());
+        return menu;
+    }
+
+    private void ShowMainWindow()
+    {
+        var w = _resolveMainWindow();
+        if (w is null) return;
+        if (w.WindowState == WindowState.Minimized) w.WindowState = WindowState.Normal;
+        w.Show();
+        w.Activate();
+        w.Topmost = true;
+        w.Topmost = false;
+    }
+
+    private static Icon LoadEmbeddedIcon()
+    {
+        // Pulled from the WPF Resource items in the csproj via the application
+        // pack URI. Falling back to SystemIcons keeps the tray usable if the
+        // resource is somehow missing.
+        try
+        {
+            var uri = new Uri("pack://application:,,,/webhook-server.ico", UriKind.Absolute);
+            using var stream = Application.GetResourceStream(uri).Stream;
+            return new Icon(stream);
+        }
+        catch
+        {
+            return SystemIcons.Application;
+        }
+    }
+
+    public void ShowBalloon(string title, string message)
+    {
+        _icon.BalloonTipTitle = title;
+        _icon.BalloonTipText = message;
+        _icon.ShowBalloonTip(3000);
+    }
+
+    public void Dispose()
+    {
+        _icon.Visible = false;
+        _icon.Dispose();
+    }
+}

src/WebhookServer.Gui/WebhookServer.Gui.csproj

@@ -14,6 +14,7 @@
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <UseWPF>true</UseWPF>
+    <UseWindowsForms>true</UseWindowsForms>
     <ApplicationIcon>..\..\resources\webhook-server.ico</ApplicationIcon>
     <AssemblyTitle>Webhook Server</AssemblyTitle>
   </PropertyGroup>