Fix: Faster startup, bounded D-Bus waits

docs/linux-port/investigations/startup-time.md

@@ -0,0 +1,130 @@
+# Startup time investigation
+
+Reported baseline: host start to first window about 1.0 s warm; fresh Debian 13
+container about 3.5 s warm and 6.8 s first run. These are inputs, not measurements
+made in this sandbox. A mapped window, first backdrop render and usable folder
+listing are different endpoints; record all three when comparing changes.
+
+## Phases and tracing
+
+Set `FILES_TRACE=1` for opt-in, bounded asynchronous stderr records. Existing
+`PerformanceTrace` scopes report duration, parent id and thread, without paths.
+New scopes cover:
+
+| Phase | Trace operation | Work and ordering |
+| --- | --- | --- |
+| Root environment | startup.root-environment | Security checks before any host setup; must stay synchronous. |
+| Instance ownership | startup.single-instance | D-Bus ownership/forwarding, socket fallback; must precede window creation. Existing 3 s connect and 5 s forwarding budgets retained to avoid duplicate windows. |
+| Cursor | startup.cursor | X resources, then up to two read-only gsettings processes before host creation. |
+| App resources | startup.app-resources | App XAML and exception hook setup; stale archive cleanup already runs on a worker. |
+| Activation | startup.activation | DI, eager managers, placement, backdrop, navigation and component scheduling. |
+| DI registration | startup.configure-services | File logger, registrations, provider build. Most singleton registrations are lazy. |
+| User settings | startup.user-settings | Synchronous JSON settings initialization when first resolved; theme, placement and restored tabs depend on settings. |
+| Window resources | startup.window-resources | MainWindow constructor/XAML/title setup (base constructor outside scope). |
+| Theme discovery | startup.theme-detection | Portal read followed by GTK environment, KDE file and gsettings fallback. |
+| First backdrop | startup.first-backdrop | Frame/theme/backdrop preparation, compositor commit, activation and first Rendered event with loaded root. |
+| Navigation/components | startup.navigation-and-components | Command-line/session navigation and background component scheduling after backdrop render. |
+
+Scopes overlap: do not sum nested durations. Program/native runtime loading before
+App construction is not included in activation. Existing `dbus-connect`,
+`dbus.theme`, `process-start` and file-operation traces provide further detail.
+First-backdrop is a framework render acknowledgement, not proof that the display
+server presented pixels. External window timestamps are still needed.
+
+## Changes and expected savings
+
+Desktop startup previously called Activate directly and immediately constructed
+main content. It now uses the existing ActivateWithBackdropAsync helper, which
+awaits a lightweight backdrop render before navigation. Terminal discovery and
+Sentry configuration follow that render. Main content, drives and startup tasks
+therefore cannot monopolize the UI thread before the backdrop acknowledgement.
+Settings, placement, eager manager resolution and initial theme stay before it;
+moving those blindly could break dependencies or flash the wrong theme.
+
+Theme portal discovery now has a 250 ms synchronous wait, bounded connect and
+read waits, and returns each read's result directly instead of shared `_lastRead`.
+Late worker failures are caught. Theme gsettings waits shrink from 1500 to 250 ms;
+cursor fallback waits shrink from 1500 to 250 ms per missing setting. Slow portal
+sessions can initially use the local fallback; the existing portal watcher still
+updates theme on change. User-action portal and mount timeouts remain unchanged.
+The theme watcher may finish after the foreground wait; this is not cancellation
+of a remote D-Bus method. Existing shared connection lifecycle is retained.
+
+Expected savings, **unmeasured**:
+
+- Unresponsive theme portal: up to 1.75 s less foreground waiting per detection.
+- Slow theme gsettings fallback: up to 1.25 s less waiting per detection.
+- Two slow cursor fallback processes: up to 2.5 s less waiting total.
+- Deferring navigation, terminal discovery and Sentry: moves their pre-yield CPU
+  and I/O cost after backdrop render; amount depends on session and first-run data.
+- Healthy services: timeout reductions alone save approximately zero; process
+  startup, XAML parsing, fontconfig and renderer initialization remain.
+
+These are wait-budget differences, not additive predictions for the supplied
+3.5/6.8 s timings. Process creation and termination, local file reads and native
+calls are not hard-bounded by these waits. Container renderer choice, font caches,
+filesystem caches and portal availability can explain substantial differences.
+
+## Services, storage and icons
+
+App.xaml.cs initializes XAML/handlers, not the entire service graph. App.Desktop.cs
+registers services then eagerly resolves QuickAccessManager, StorageHistoryWrapper,
+FileTagsManager, LibraryManager, logger and AppModel. AppModel is constructed on
+the UI thread for Clipboard.ContentChanged. Preserve that affinity.
+
+UserSettingsService/BaseJsonSettings and serializers use JSON files. The desktop
+FileTagsDatabase.Linux implementation lazily loads JSON; StorageHistoryWrapper is
+in memory. A SQLite package reference does not establish a startup DB open.
+InitializeAppComponentsAsync already schedules pinned items, libraries, cloud
+sections and tag updates on workers after navigation. DrivesViewModel constructs
+a watcher and enumerates via GetDrivesAsync when updated; this work is downstream
+of navigation. Keep mount/polkit operation budgets unchanged.
+
+LinuxIconThemeProvider discovers theme via environment and GTK/KDE configuration
+and indexes icon files; it does not spawn a portal/gsettings process for theme
+selection. MainWindow already schedules its window icon after the next render.
+PortalWallpaperService is invoked for wallpaper actions, not eager startup
+wallpaper discovery; DesktopWallpaperService is a stub. Its 5 s call/10 minute
+confirmation budgets should not be shortened for startup.
+
+## Publishing, JIT and globalization
+
+Files.App.csproj already sets PublishReadyToRun=true for non-Debug builds with a
+RID, with composite R2R disabled. scripts/linux/publish.sh supplies Release and a
+Linux RID, so its tarball publish already requests R2R. The script now explicitly
+passes PublishReadyToRun=true so this packaging intent is visible. The analysis
+publish profile also enables it. No published tarball was available for binary
+verification here. The previous project comment's 25–30% claim is not a measured
+result for the supplied Debian environment.
+
+R2R does not eliminate assembly loading, XAML initialization, native library
+loading or all JIT compilation. No explicit tiered compilation/TieredPGO or
+runtime ReadyToRun overrides were found in the app/publishing paths examined;
+retain runtime defaults rather than trading later responsiveness for speculative
+startup gains. Benchmark the same Release RID publication with R2R on/off, and
+inspect Files.runtimeconfig.json plus DOTNET_/COMPlus_ overrides. Compare file
+size and page faults as well as latency; a larger R2R payload can cost cold I/O.
+
+Do not enable InvariantGlobalization for Files.App. AppLanguageHelper constructs
+named cultures and the date formatter uses the selected language's CultureInfo;
+localized formatting and sorting need real globalization. Only the isolated
+ElevationHelper explicitly uses invariant mode. Preserve app ICU availability;
+measure its loading cost rather than disabling culture support.
+
+## Validation and next measurements
+
+The sandbox cannot build/run the Uno desktop app. Platform tests validate the
+Linux changes, but do not compile App.Desktop/MainWindow. Review the app changes
+by reference searches and run desktop build and UI checks on a supported host.
+Use scripts/linux/headless-run.sh with its private display/throwaway home; never
+use the user's display or real settings. Capture FILES_TRACE stderr for repeated
+warm runs and fresh-home first runs of the same published artifact. Record runtime
+version, RID, renderer, portal availability and cache state. Compare backdrop and
+listing readiness separately, including closing the window during startup.
+
+Validation in this sandbox: single-node platform build passed with
+`-p:NuGetAudit=false` (network auditing failed on the initial attempt); direct
+runner: 1208 passed, 41 skipped, 13 failed (X11 display setup and native-directory
+fixtures). Focused CursorSettingsResolverTests: 9 passed. `git diff --check` and
+`bash -n scripts/linux/publish.sh` passed. Desktop build/run and published binary
+verification were not performed; no measured latency improvement is claimed.

scripts/linux/publish.sh

@@ -30,7 +30,7 @@ rm -rf "$out"
 MSBUILDDISABLENODEREUSE=1 nice -n 19 dotnet publish "$root/src/Files.App/Files.App.csproj" \
   -f net10.0-desktop -c Release -r "$rid" \
   --self-contained "$self_contained" \
-  -p:PublishTrimmed=false -p:PublishAot=false \
+  -p:PublishTrimmed=false -p:PublishAot=false -p:PublishReadyToRun=true \
   -nodeReuse:false -m:2 -o "$out"
 
 # This AOT executable is installed separately, root-owned, by native packages only.

src/Files.App/App.xaml.cs

@@ -53,6 +53,7 @@ public static FlyoutBase? LastOpenedFlyout
 		/// </summary>
 		public App()
 		{
+			using var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.app-resources", true);
 			InitializeComponent();
 
 			// Configure exception handlers

src/Files.App/Files.App.csproj

@@ -30,7 +30,7 @@
         <!--  XAML cannot see generator output on Uno; ICommandManager is checked in under Platforms/Desktop/Generated  -->
         <FilesPregeneratedICommandManager Condition="'$(FilesPregeneratedICommandManager)' == ''">true</FilesPregeneratedICommandManager>
         <DefineConstants>$(DefineConstants);DESKTOP</DefineConstants>
-        <!--  Precompile (ReadyToRun) published Linux builds: roughly 25-30% faster cold start. Composite stays off (self-contained Uno assemblies)  -->
+        <!--  Precompile (ReadyToRun) published Linux builds to reduce startup JIT work. Composite stays off (self-contained Uno assemblies)  -->
         <PublishReadyToRun Condition="'$(Configuration)' != 'Debug' and '$(RuntimeIdentifier)' != ''">true</PublishReadyToRun>
         <PublishReadyToRunComposite>false</PublishReadyToRunComposite>
     </PropertyGroup>

src/Files.App/Helpers/Application/AppLifecycleHelper.cs

@@ -302,6 +302,7 @@ public static void ConfigureSentry()
 		/// <param name="appModel">Constructed on the UI thread by the caller (its ctor is UI-thread-only).</param>
 		public static IServiceProvider ConfigureHost(AppModel appModel)
 		{
+			using var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.configure-services", true);
 			var services = new ServiceCollection();
 			var fileLoggerProvider = new FileLoggerProvider(Path.Combine(ApplicationData.Current.LocalFolder.Path, "debug.log"));
 
@@ -414,6 +415,12 @@ public static IServiceProvider ConfigureHost(AppModel appModel)
 		/// </summary>
 		public static void SaveSessionTabs()
 		{
+#if DESKTOP
+			// Navigation can still be restoring tabs while the window closes.
+			if (!MainPageViewModel.StartupTabsLoadedTask.IsCompletedSuccessfully)
+				return;
+#endif
+
 			var userSettingsService = Ioc.Default.GetRequiredService<IUserSettingsService>();
 
 			userSettingsService.GeneralSettingsService.LastSessionTabList = MainPageViewModel.AppInstances.DefaultIfEmpty().Select(tab =>

src/Files.App/MainWindow.xaml.cs

@@ -31,6 +31,7 @@ public sealed partial class MainWindow : WindowEx
 
 		public MainWindow() : base(416, 316)
 		{
+			using var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.window-resources", true);
 			InitializeComponent();
 
 			ExtendsContentIntoTitleBar = UseClientSideDecorations;

src/Files.App/Platforms/Desktop/App.Desktop.cs

@@ -30,12 +30,9 @@ protected override void OnLaunched(LaunchActivatedEventArgs e)
 
 			async Task ActivateAsync()
 			{
+				using var startupTrace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.activation", true);
 				var serviceProvider = AppLifecycleHelper.ConfigureHost(AppModel);
 				Ioc.Default.ConfigureServices(serviceProvider);
-				RootActionsHelper.InitializeTerminalAvailability();
-
-				if (AppLifecycleHelper.AppEnvironment is not AppEnvironment.Dev)
-					AppLifecycleHelper.ConfigureSentry();
 
 				// TODO: Replace with DI
 				QuickAccessManager = Ioc.Default.GetRequiredService<QuickAccessManager>();
@@ -46,14 +43,23 @@ async Task ActivateAsync()
 				AppModel = Ioc.Default.GetRequiredService<AppModel>();
 
 				MainWindow.Instance.RestorePlacement(Ioc.Default.GetRequiredService<Files.Platform.Abstractions.ILocalSettingsStore>());
-				MainWindow.Instance.Activate();
-				UiResponsivenessProbe.Start(UiDispatcher!);
-
 				MainWindow.Instance.Closed += Window_Closed;
 				MainWindow.Instance.Activated += Window_Activated;
 
+				using (var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.first-backdrop", true))
+				{
+					if (!await MainWindow.Instance.ActivateWithBackdropAsync())
+						return;
+				}
+
+				RootActionsHelper.InitializeTerminalAvailability();
+				if (AppLifecycleHelper.AppEnvironment is not AppEnvironment.Dev)
+					AppLifecycleHelper.ConfigureSentry();
+				UiResponsivenessProbe.Start(UiDispatcher!);
+
 				Logger.LogInformation("App launched (desktop).");
 
+				using var navigationTrace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.navigation-and-components", true);
 				// Command line (paths, --select, -t, -n) of this process; later launches arrive through ISingleInstanceService
 				var launchOptions = Files.App.Utils.CommandLine.DesktopCommandLine.Parse(Program.LaunchArguments, Environment.CurrentDirectory);
 				if (launchOptions.IsEmpty)
@@ -144,7 +150,7 @@ private async void Window_Closed(object sender, WindowEventArgs args)
 
 			if (userSettingsService.GeneralSettingsService.ContinueLastSessionOnStartUp || userSettingsService.AppSettingsService.RestoreTabsOnStartup)
 				AppLifecycleHelper.SaveSessionTabs();
-			else
+			else if (MainPageViewModel.StartupTabsLoadedTask.IsCompletedSuccessfully)
 				await commandManager.CloseAllTabs.ExecuteAsync();
 
 			// TODO: "leave app running" (background parking) is not supported on desktop yet

src/Files.App/Platforms/Desktop/Program.cs

@@ -41,6 +41,7 @@ public static int Main(string[] args)
 		{
 			try
 			{
+				using var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.root-environment");
 				RootStartupEnvironment.Apply();
 			}
 			catch (System.IO.IOException)
@@ -76,6 +77,7 @@ public static int Main(string[] args)
 				bool isPrimary;
 				try
 				{
+					using var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.single-instance");
 					isPrimary = singleInstance.TryBecomePrimaryAsync(request).GetAwaiter().GetResult();
 				}
 				catch (Exception ex) when (ex is System.IO.IOException or InvalidOperationException or System.Net.Sockets.SocketException or UnauthorizedAccessException)
@@ -97,7 +99,8 @@ public static int Main(string[] args)
 			var (renderingBackend, reason) = RenderingBackendSelector.Resolve(Environment.GetEnvironmentVariable, RenderingBackendSelector.HasGpuDevice);
 			Console.Error.WriteLine($"[Files] Rendering backend: {renderingBackend} ({reason ?? "default"})");
 
-			CursorSettingsResolver.ApplyToProcess();
+			using (var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.cursor"))
+				CursorSettingsResolver.ApplyToProcess();
 
 			var host = UnoPlatformHostBuilder.Create()
 				.App(() => new App())

src/Files.App/Services/Settings/UserSettingsService.cs

@@ -91,6 +91,7 @@ public IAppSettingsService AppSettingsService
 
 		public UserSettingsService()
 		{
+			using var trace = Files.Platform.Abstractions.Diagnostics.PerformanceTrace.Begin("startup.user-settings", true);
 			var settingsSerializer = new DefaultSettingsSerializer(message => App.Logger.LogWarning(message));
 			SettingsSerializer = settingsSerializer;