Add dev/debug startup flow and launch profiles

Handle design-time initialization and add a developer debug startup path: App now skips normal startup when in design mode and shows a DevDebugWindow when running in debug (unless a preview or apply-update command). CommandContext.IsDebugMode is extended to include DOTNET_ENVIRONMENT=Development via a new IsDevelopmentEnvironment helper. Program.Main and BuildAvaloniaApp are made public to aid tooling. Added multiple launchSettings profiles for debug and preview commands that set DOTNET_ENVIRONMENT=Development to simplify IDE debugging and UI previewing.

LanMountainDesktop.Launcher/App.axaml.cs

@@ -18,6 +18,12 @@ public partial class App : Application
 {
     public override void Initialize()
     {
+        if (Design.IsDesignMode)
+        {
+            AvaloniaXamlLoader.Load(this);
+            return;
+        }
+
         Logger.Initialize();
         var context = LauncherRuntimeContext.Current;
         var execution = LauncherExecutionContext.Capture();
@@ -32,6 +38,12 @@ public partial class App : Application
 
     public override void OnFrameworkInitializationCompleted()
     {
+        if (Design.IsDesignMode)
+        {
+            base.OnFrameworkInitializationCompleted();
+            return;
+        }
+
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
             desktop.ShutdownMode = ShutdownMode.OnExplicitShutdown;
@@ -49,6 +61,18 @@ public partial class App : Application
                 return;
             }
 
+            // 调试模式：只显示 DevDebugWindow，不走正常启动流程
+            // 避免启动主程序后 Launcher 自动退出，导致开发者无法预览 UI
+            if (context.IsDebugMode && !context.IsPreviewCommand &&
+                !string.Equals(context.Command, "apply-update", StringComparison.OrdinalIgnoreCase))
+            {
+                Logger.Info("Debug mode active — showing DevDebugWindow instead of normal launch flow.");
+                var devDebugWindow = new DevDebugWindow();
+                devDebugWindow.Show();
+                base.OnFrameworkInitializationCompleted();
+                return;
+            }
+
             if (string.Equals(context.Command, "apply-update", StringComparison.OrdinalIgnoreCase))
             {
                 var updateWindow = new UpdateWindow();

LanMountainDesktop.Launcher/CommandContext.cs

@@ -37,11 +37,25 @@ internal sealed class CommandContext
 
     /// <summary>
     /// 是否处于调试模式（从 Rider/VS 等 IDE 启动）
-    /// 仅当明确指定 --debug 参数或调试器附加时才启用
+    /// 当满足以下任一条件时启用：
+    /// 1. 明确指定 --debug 参数
+    /// 2. 调试器附加（Debugger.IsAttached）
+    /// 3. DOTNET_ENVIRONMENT 环境变量为 Development（IDE 调试启动时自动设置）
     /// </summary>
     public bool IsDebugMode =>
         Options.ContainsKey("debug") ||
-        System.Diagnostics.Debugger.IsAttached;
+        System.Diagnostics.Debugger.IsAttached ||
+        IsDevelopmentEnvironment;
+
+    /// <summary>
+    /// 是否为 Development 环境（DOTNET_ENVIRONMENT=Development）
+    /// Rider/VS 调试启动时会自动设置此环境变量
+    /// </summary>
+    public bool IsDevelopmentEnvironment =>
+        string.Equals(
+            System.Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT"),
+            "Development",
+            StringComparison.OrdinalIgnoreCase);
 
     public bool IsPreviewCommand =>
         Command.StartsWith("preview-", StringComparison.OrdinalIgnoreCase);

LanMountainDesktop.Launcher/Program.cs

@@ -4,10 +4,10 @@ using LanMountainDesktop.Launcher.Services;
 
 namespace LanMountainDesktop.Launcher;
 
-internal static class Program
+public static class Program
 {
     [STAThread]
-    private static async Task<int> Main(string[] args)
+    public static async Task<int> Main(string[] args)
     {
         var commandContext = CommandContext.FromArgs(args);
         var execution = LauncherExecutionContext.Capture();
@@ -66,7 +66,7 @@ internal static class Program
         }
     }
 
-    private static AppBuilder BuildAvaloniaApp()
+    public static AppBuilder BuildAvaloniaApp()
     {
         return AppBuilder.Configure<App>()
             .UsePlatformDetect()

LanMountainDesktop.Launcher/Properties/launchSettings.json

@@ -1,6 +1,14 @@
 {
   "$schema": "http://json.schemastore.org/launchsettings.json",
   "profiles": {
+    "Launcher (Debug Mode)": {
+      "commandName": "Project",
+      "commandLineArgs": "launch --debug",
+      "workingDirectory": "$(SolutionDir)",
+      "environmentVariables": {
+        "DOTNET_ENVIRONMENT": "Development"
+      }
+    },
     "Launcher (Launch Mode)": {
       "commandName": "Project",
       "commandLineArgs": "launch",
@@ -9,6 +17,46 @@
         "DOTNET_ENVIRONMENT": "Development"
       }
     },
+    "Launcher (Preview Debug Window)": {
+      "commandName": "Project",
+      "commandLineArgs": "preview-debug",
+      "workingDirectory": "$(SolutionDir)",
+      "environmentVariables": {
+        "DOTNET_ENVIRONMENT": "Development"
+      }
+    },
+    "Launcher (Preview Splash)": {
+      "commandName": "Project",
+      "commandLineArgs": "preview-splash",
+      "workingDirectory": "$(SolutionDir)",
+      "environmentVariables": {
+        "DOTNET_ENVIRONMENT": "Development"
+      }
+    },
+    "Launcher (Preview Error)": {
+      "commandName": "Project",
+      "commandLineArgs": "preview-error",
+      "workingDirectory": "$(SolutionDir)",
+      "environmentVariables": {
+        "DOTNET_ENVIRONMENT": "Development"
+      }
+    },
+    "Launcher (Preview Update)": {
+      "commandName": "Project",
+      "commandLineArgs": "preview-update",
+      "workingDirectory": "$(SolutionDir)",
+      "environmentVariables": {
+        "DOTNET_ENVIRONMENT": "Development"
+      }
+    },
+    "Launcher (Preview OOBE)": {
+      "commandName": "Project",
+      "commandLineArgs": "preview-oobe",
+      "workingDirectory": "$(SolutionDir)",
+      "environmentVariables": {
+        "DOTNET_ENVIRONMENT": "Development"
+      }
+    },
     "Launcher (Update Check)": {
       "commandName": "Project",
       "commandLineArgs": "update check",