Add --isolated for per-launch process isolation

README.md

@@ -88,6 +88,14 @@ settings file. On Windows, `WT_PARENT_WINDOW_HANDLE` embeds the window as a
 child of that HWND. `alwaysShowTabs: false` hides the tab row when only one
 tab is open.
 
+`dt --isolated` (or `Devolutions.Terminal.exe --isolated`) runs the launch in
+its own process: it neither forwards to a running instance nor becomes the
+broker for later launches, so every window keeps its own environment,
+`WT_PARENT_WINDOW_HANDLE`, and settings directory. `-w` targeting of other
+windows is unavailable, and persisted layouts are neither restored nor saved.
+It is the per-launch equivalent of Windows Terminal's
+`compatibility.isolatedMode` setting, which Windows Terminal 1.23 removed.
+
 Set `"experimental.terminalEngine": "ghostty"` to use the pinned
 `libghostty-vt` engine globally. A profile can override it with `"builtin"` or
 `"ghostty"`. ConPTY remains the Windows process transport for both engines.

src/Devolutions.Terminal.App/Models/TerminalLayoutStateStore.cs

@@ -10,6 +10,10 @@ preference is not null &&
          preference.Equals("persistedWindowLayout", StringComparison.OrdinalIgnoreCase) ||
          preference.Equals("persistedLayoutAndContent", StringComparison.OrdinalIgnoreCase));
 
+    // Matches Windows Terminal: an isolated process never restores or saves the shared window layouts.
+    public static bool ShouldUsePersistedLayout(string? firstWindowPreference, bool isolated) =>
+        !isolated && IsPersistedLayoutPreference(firstWindowPreference);
+
     public static WindowLayoutState? ReadWindowState(ApplicationStateStore store, int windowId)
     {
         ArgumentNullException.ThrowIfNull(store);

src/Devolutions.Terminal.App/Views/MainWindow.axaml.cs

@@ -77,6 +77,7 @@ public partial class MainWindow :
     private readonly Func<GlobalSummonArgs, ValueTask<WindowActionResult>>? _summonRequested;
     private readonly Action<AppSettings>? _settingsChanged;
     private readonly ISystemMenuService _systemMenuService;
+    private readonly bool _isolated;
     private readonly TaskCompletionSource<TerminalWindowActivationResult> _initialActivationCompletion =
         new(TaskCreationOptions.RunContinuationsAsynchronously);
     private readonly DispatcherTimer _notificationTimer;
@@ -102,10 +103,12 @@ public MainWindow(
         Action<string>? workspaceRequested = null,
         Func<GlobalSummonArgs, ValueTask<WindowActionResult>>? summonRequested = null,
         Action<AppSettings>? settingsChanged = null,
-        ISystemMenuService? systemMenuService = null)
+        ISystemMenuService? systemMenuService = null,
+        bool isolated = false)
     {
         WindowId = windowId;
         WindowName = windowName;
+        _isolated = isolated;
         _initialActivation = initialActivation;
         _newWindowRequested = newWindowRequested;
         _tabTearOffRequested = tabTearOffRequested;
@@ -3647,8 +3650,7 @@ private void PersistWorkspace(TerminalWindowLayoutDescriptor layout)
     };
 
     private bool UsesPersistedLayout =>
-        TerminalLayoutStateStore.IsPersistedLayoutPreference(
-            _settings.FirstWindowPreference);
+        TerminalLayoutStateStore.ShouldUsePersistedLayout(_settings.FirstWindowPreference, _isolated);
 
     private void TryPersistCurrentLayout(TerminalWindowLayoutDescriptor layout)
     {

src/Devolutions.Terminal.Cli/CliContracts.cs

@@ -24,7 +24,8 @@ public sealed record CliInvocation(
     CliLaunchMode LaunchMode,
     int? SavedLayout,
     IReadOnlyList<ActionAndArgs> Actions,
-    CliSaveRequest? SaveRequest = null);
+    CliSaveRequest? SaveRequest = null,
+    bool Isolated = false);
 
 public sealed record CliParseResult(
     int ExitCode,

src/Devolutions.Terminal.Cli/CliParser.cs

@@ -118,6 +118,7 @@ private static CliParseResult ParseCore(
         int? rows = null;
         int? savedLayout = null;
         var launchMode = CliLaunchMode.Default;
+        var isolated = false;
         CliSaveRequest? save = null;
 
         for (var segmentIndex = 0; segmentIndex < segments.Count; segmentIndex++)
@@ -135,7 +136,8 @@ private static CliParseResult ParseCore(
                     ref columns,
                     ref rows,
                     ref savedLayout,
-                    ref launchMode);
+                    ref launchMode,
+                    ref isolated);
             }
 
             var command = index < segment.Count && Commands.Contains(segment[index])
@@ -215,7 +217,8 @@ save is null &&
             launchMode,
             savedLayout,
             actions,
-            save);
+            save,
+            isolated);
         return new(0, string.Empty, false, invocation);
     }
 
@@ -228,7 +231,8 @@ private static void ParseRootOptions(
         ref int? columns,
         ref int? rows,
         ref int? savedLayout,
-        ref CliLaunchMode launchMode)
+        ref CliLaunchMode launchMode,
+        ref bool isolated)
     {
         while (index < args.Count)
         {
@@ -269,6 +273,10 @@ private static void ParseRootOptions(
                     launchMode |= CliLaunchMode.Focus;
                     index++;
                     break;
+                case "--isolated":
+                    isolated = true;
+                    index++;
+                    break;
                 default:
                     if (option.StartsWith('-') &&
                         option.Length > 2 &&
@@ -696,6 +704,7 @@ internal static class CommandLineSchema
           -M, --maximized        Launch maximized
           -F, --fullscreen       Launch fullscreen
           -f, --focus            Hide the title bar
+          --isolated             Own process: never join or serve other launches
 
         Commands:
           new-tab, nt   split-pane, sp   focus-tab, ft   move-focus, mf
@@ -708,6 +717,7 @@ public static RootCommand Create()
         root.Options.Add(new Option<string>("--window") { Description = "Target window." });
         root.Options.Add(new Option<string>("--pos") { Description = "Window position." });
         root.Options.Add(new Option<string>("--size") { Description = "Terminal size." });
+        root.Options.Add(new Option<bool>("--isolated") { Description = "Run in its own process." });
         foreach (var (name, alias) in new[]
                  {
                      ("new-tab", "nt"),

src/Devolutions.Terminal.Cli/Program.cs

@@ -17,9 +17,11 @@ public static async Task<int> Main(string[] args)
         }
 
         var invocation = parsed.Invocation!;
-        var response = await new BrokerClient().SendAsync(
-            invocation.TargetWindow,
-            CliInvocationSerializer.Serialize(invocation)).ConfigureAwait(false);
+        var response = invocation.Isolated
+            ? BrokerResponse.Unavailable("Isolated launches do not use the broker.")
+            : await new BrokerClient().SendAsync(
+                invocation.TargetWindow,
+                CliInvocationSerializer.Serialize(invocation)).ConfigureAwait(false);
         if (response.Status == BrokerStatus.Unavailable)
         {
             if (RequiresExistingWindow(invocation.TargetWindow))

src/Devolutions.Terminal/App.axaml.cs

@@ -30,7 +30,10 @@ public override void OnFrameworkInitializationCompleted()
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
             _desktop = desktop;
-            _router = new TerminalWindowRouter(desktop, ConfigureWindow);
+            _router = new TerminalWindowRouter(
+                desktop,
+                ConfigureWindow,
+                isolated: InitialInvocation?.Isolated ?? false);
             BrokerHandler?.SetHandler(_router);
             if (OperatingSystem.IsMacOS())
             {

src/Devolutions.Terminal/Program.cs

@@ -67,30 +67,34 @@ public static int Main(string[] args)
 
         var invocation = parsed.Invocation!;
         var deferredHandler = new DeferredBrokerHandler();
-        var broker = BrokerHost.TryCreate(deferredHandler);
-        if (broker is null)
+        BrokerHost? broker = null;
+        if (!invocation.Isolated)
         {
-            var response = ForwardToPrimaryAsync(invocation).AsTask().GetAwaiter().GetResult();
-            if (!response.IsSuccess)
+            broker = BrokerHost.TryCreate(deferredHandler);
+            if (broker is null)
             {
-                Console.Error.WriteLine($"dt: {response.Message}");
-                return response.Status == BrokerStatus.WindowNotFound ? 3 : 1;
-            }
+                var response = ForwardToPrimaryAsync(invocation).AsTask().GetAwaiter().GetResult();
+                if (!response.IsSuccess)
+                {
+                    Console.Error.WriteLine($"dt: {response.Message}");
+                    return response.Status == BrokerStatus.WindowNotFound ? 3 : 1;
+                }
 
-            return 0;
+                return 0;
+            }
         }
 
         if (invocation.TargetWindow.Equals("use-existing", StringComparison.OrdinalIgnoreCase) ||
             (int.TryParse(invocation.TargetWindow, out var requestedWindowId) && requestedWindowId > 0))
         {
-            broker.DisposeAsync().AsTask().GetAwaiter().GetResult();
+            broker?.DisposeAsync().AsTask().GetAwaiter().GetResult();
             Console.Error.WriteLine($"dt: terminal window '{invocation.TargetWindow}' was not found.");
             return 3;
         }
 
         if (invocation.SaveRequest is { Commandline.Length: > 0 } saveRequest)
         {
-            broker.DisposeAsync().AsTask().GetAwaiter().GetResult();
+            broker?.DisposeAsync().AsTask().GetAwaiter().GetResult();
             try
             {
                 var settings = Devolutions.Terminal.Settings.SettingsService.Load();
@@ -135,7 +139,7 @@ IOException or
         }
         finally
         {
-            broker.DisposeAsync().AsTask().GetAwaiter().GetResult();
+            broker?.DisposeAsync().AsTask().GetAwaiter().GetResult();
         }
     }
 

src/Devolutions.Terminal/TerminalWindowRouter.cs

@@ -17,16 +17,19 @@ internal sealed class TerminalWindowRouter : IBrokerRequestHandler, IDisposable
     private readonly ApplicationStateStore _stateStore;
     private readonly GlobalWindowActionRouter _windowActions;
     private readonly GlobalHotkeyManager _globalHotkeys;
+    private readonly bool _isolated;
     private int _nextWindowId = 1;
 
     public TerminalWindowRouter(
         IClassicDesktopStyleApplicationLifetime desktop,
         Action<MainWindow>? windowCreated = null,
         ApplicationStateStore? stateStore = null,
-        IGlobalHotkeyBackend? globalHotkeyBackend = null)
+        IGlobalHotkeyBackend? globalHotkeyBackend = null,
+        bool isolated = false)
     {
         _desktop = desktop;
         _windowCreated = windowCreated;
+        _isolated = isolated;
         _stateStore = stateStore ?? SettingsService.LoadApplicationState();
         _windowActions = new GlobalWindowActionRouter(CreateSummonWindow);
         _globalHotkeys = new GlobalHotkeyManager(
@@ -146,7 +149,8 @@ private MainWindow CreateWindow(TerminalWindowActivation activation, string name
                         : $"{window.WindowName} ({window.WindowId})")
                 .ToArray(),
             summonRequested: args => _windowActions.SummonAsync(window, args),
-            settingsChanged: settings => TraceHotkeyResults(_globalHotkeys.Apply(settings.ActionMap)));
+            settingsChanged: settings => TraceHotkeyResults(_globalHotkeys.Apply(settings.ActionMap)),
+            isolated: _isolated);
         _windows.Add(window);
         _windowActions.Add(window);
         _windowCreated?.Invoke(window);
@@ -225,11 +229,12 @@ parsed.Invocation.PositionX is not null ||
             parsed.Invocation.PositionY is not null ||
             parsed.Invocation.Columns is not null ||
             parsed.Invocation.Rows is not null ||
-            parsed.Invocation.LaunchMode != CliLaunchMode.Default)
+            parsed.Invocation.LaunchMode != CliLaunchMode.Default ||
+            parsed.Invocation.Isolated)
         {
             return new(
                 false,
-                "Window routing, position, size, and launch-mode options are not valid inside the current window's command palette.",
+                "Window routing, position, size, launch-mode, and isolation options are not valid inside the current window's command palette.",
                 []);
         }
 

tests/Devolutions.Terminal.App.Tests/LayoutDescriptorTests.cs

@@ -28,6 +28,16 @@ public void NonPersistedFirstWindowPreferencesDoNotRestoreLayouts(string? prefer
         Assert.False(TerminalLayoutStateStore.IsPersistedLayoutPreference(preference));
     }
 
+    [Theory]
+    [InlineData("persistedWindowLayout", false, true)]
+    [InlineData("persistedWindowLayout", true, false)]
+    [InlineData("defaultProfile", false, false)]
+    [InlineData("defaultProfile", true, false)]
+    public void IsolatedModeNeverUsesPersistedLayouts(string preference, bool isolated, bool expected)
+    {
+        Assert.Equal(expected, TerminalLayoutStateStore.ShouldUsePersistedLayout(preference, isolated));
+    }
+
     [Fact]
     public void WindowTabPaneLayoutRoundTripsThroughApplicationState()
     {

tests/Devolutions.Terminal.Cli.Tests/CliParserTests.cs

@@ -122,6 +122,29 @@ public void RootLaunchOptionsArePreserved()
         Assert.Equal(40, result.Rows);
         Assert.True(result.LaunchMode.HasFlag(CliLaunchMode.Maximized));
         Assert.True(result.LaunchMode.HasFlag(CliLaunchMode.Focus));
+        Assert.False(result.Isolated);
+    }
+
+    [Fact]
+    public void IsolatedIsARootOptionThatKeepsTheCommandLine()
+    {
+        var result = Parse("--isolated", "-w", "new", "new-tab", "-p", "cmd", "cmd.exe", "/k", "--isolated");
+
+        Assert.True(result.Isolated);
+        Assert.Equal("new", result.TargetWindow);
+        var terminal = Assert.IsType<NewTerminalArgs>(
+            Assert.IsType<NewTabArgs>(Assert.Single(result.Actions).Args).ContentArgs);
+        Assert.Equal("cmd", terminal.Profile);
+        Assert.Equal("cmd.exe /k --isolated", terminal.Commandline);
+    }
+
+    [Fact]
+    public void IsolatedAfterACommandIsRejected()
+    {
+        var result = new CliParser().Parse(["new-tab", "--isolated"]);
+
+        Assert.Equal(2, result.ExitCode);
+        Assert.Equal("dt: Unknown command '--isolated'.", result.Message);
     }
 
     [Fact]