Fix CmdPal application activation (#40162)

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fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request

This PR:
- Fixes the passing of activation arguments between instances.
- Adds defensive handling of exceptions if the activation argument is
corrupted.
- Ensures that the activation method is consistently handled on the main
thread.
- Updates the condition under which the main window is displayed after
startup or activation.

The main window will now be automatically shown when the app is started
or activated, except in the following cases:
- when started as a startup task,
- when started using x-cmdpal://background,
- when started using x-cmdpal://settings.

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## PR Checklist

- [x] **Closes:** #39681
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

---------

Co-authored-by: Mike Griese <migrie@microsoft.com>

.github/actions/spell-check/expect.txt

@@ -287,6 +287,7 @@ CVal
 cvd
 CVirtual
 CVS
+CWMO
 CXSCREEN
 CXSMICON
 CXVIRTUALSCREEN

src/modules/cmdpal/Microsoft.CmdPal.UI/MainWindow.xaml.cs

@@ -6,6 +6,7 @@ using System.Diagnostics;
 using System.Runtime.InteropServices;
 using CmdPalKeyboardService;
 using CommunityToolkit.Mvvm.Messaging;
+using ManagedCommon;
 using Microsoft.CmdPal.Common.Helpers;
 using Microsoft.CmdPal.Common.Messages;
 using Microsoft.CmdPal.Common.Services;
@@ -450,30 +451,42 @@ public sealed partial class MainWindow : WindowEx,
             return;
         }
 
-        if (activatedEventArgs.Kind == Microsoft.Windows.AppLifecycle.ExtendedActivationKind.Protocol)
+        try
         {
-            if (activatedEventArgs.Data is IProtocolActivatedEventArgs protocolArgs)
+            if (activatedEventArgs.Kind == ExtendedActivationKind.StartupTask)
             {
-                if (protocolArgs.Uri.ToString() is string uri)
-                {
-                    // was the URI "x-cmdpal://background" ?
-                    if (uri.StartsWith("x-cmdpal://background", StringComparison.OrdinalIgnoreCase))
-                    {
-                        // we're running, we don't want to activate our window. bail
-                        return;
-                    }
-                    else if (uri.StartsWith("x-cmdpal://settings", StringComparison.OrdinalIgnoreCase))
-                    {
-                        WeakReferenceMessenger.Default.Send<OpenSettingsMessage>(new());
-                        return;
-                    }
-                }
-
                 return;
             }
+
+            if (activatedEventArgs.Kind == ExtendedActivationKind.Protocol)
+            {
+                if (activatedEventArgs.Data is IProtocolActivatedEventArgs protocolArgs)
+                {
+                    if (protocolArgs.Uri.ToString() is string uri)
+                    {
+                        // was the URI "x-cmdpal://background" ?
+                        if (uri.StartsWith("x-cmdpal://background", StringComparison.OrdinalIgnoreCase))
+                        {
+                            // we're running, we don't want to activate our window. bail
+                            return;
+                        }
+                        else if (uri.StartsWith("x-cmdpal://settings", StringComparison.OrdinalIgnoreCase))
+                        {
+                            WeakReferenceMessenger.Default.Send<OpenSettingsMessage>(new());
+                            return;
+                        }
+                    }
+                }
+            }
+        }
+        catch (COMException ex)
+        {
+            // Accessing properties activatedEventArgs.Kind and activatedEventArgs.Data might cause COMException
+            // if the args are not valid or not passed correctly.
+            Logger.LogError("COM exception when activating the application", ex);
         }
 
-        Activate();
+        Summon(string.Empty);
     }
 
     public void Summon(string commandId) =>

src/modules/cmdpal/Microsoft.CmdPal.UI/NativeMethods.txt

@@ -43,3 +43,7 @@ MessageBox
 DwmGetWindowAttribute
 DwmSetWindowAttribute
 DWM_CLOAKED_APP
+
+CoWaitForMultipleObjects
+INFINITE
+CWMO_FLAGS 

src/modules/cmdpal/Microsoft.CmdPal.UI/Program.cs

@@ -6,9 +6,11 @@ using System.Runtime.InteropServices;
 using ManagedCommon;
 using Microsoft.CmdPal.UI.Events;
 using Microsoft.PowerToys.Telemetry;
+using Microsoft.UI.Dispatching;
 using Microsoft.Windows.AppLifecycle;
 using Windows.Win32;
 using Windows.Win32.Foundation;
+using Windows.Win32.System.Com;
 using Windows.Win32.UI.WindowsAndMessaging;
 
 namespace Microsoft.CmdPal.UI;
@@ -18,6 +20,7 @@ namespace Microsoft.CmdPal.UI;
 // https://github.com/microsoft/WindowsAppSDK-Samples/tree/main/Samples/AppLifecycle/Instancing/cs2/cs-winui-packaged/CsWinUiDesktopInstancing
 internal sealed class Program
 {
+    private static DispatcherQueueSynchronizationContext? uiContext;
     private static App? app;
 
     // LOAD BEARING
@@ -70,8 +73,8 @@ internal sealed class Program
         {
             Microsoft.UI.Xaml.Application.Start((p) =>
             {
-                Microsoft.UI.Dispatching.DispatcherQueueSynchronizationContext context = new(Microsoft.UI.Dispatching.DispatcherQueue.GetForCurrentThread());
-                SynchronizationContext.SetSynchronizationContext(context);
+                uiContext = new DispatcherQueueSynchronizationContext(DispatcherQueue.GetForCurrentThread());
+                SynchronizationContext.SetSynchronizationContext(uiContext);
                 app = new App();
             });
         }
@@ -94,12 +97,29 @@ internal sealed class Program
         {
             isRedirect = true;
             PowerToysTelemetry.Log.WriteEvent(new ReactivateInstance());
-            keyInstance.RedirectActivationToAsync(args).AsTask().ConfigureAwait(false);
+            RedirectActivationTo(args, keyInstance);
         }
 
         return isRedirect;
     }
 
+    private static void RedirectActivationTo(AppActivationArguments args, AppInstance keyInstance)
+    {
+        // Do the redirection on another thread, and use a non-blocking
+        // wait method to wait for the redirection to complete.
+        var redirectSemaphore = new Semaphore(0, 1);
+        Task.Run(() =>
+        {
+            keyInstance.RedirectActivationToAsync(args).AsTask().Wait();
+            redirectSemaphore.Release();
+        });
+        _ = PInvoke.CoWaitForMultipleObjects(
+            (uint)CWMO_FLAGS.CWMO_DEFAULT,
+            PInvoke.INFINITE,
+            [new HANDLE(redirectSemaphore.SafeWaitHandle.DangerousGetHandle())],
+            out _);
+    }
+
     private static void OnActivated(object? sender, AppActivationArguments args)
     {
         // If we already have a form, display the message now.
@@ -109,9 +129,7 @@ internal sealed class Program
             if (thisApp.AppWindow is not null and
                 MainWindow mainWindow)
             {
-                mainWindow.HandleLaunch(args);
-
-                // mainWindow.Summon(string.Empty);
+                uiContext?.Post(_ => mainWindow.HandleLaunch(args), null);
             }
         }
     }