CmdPal: Implement GoToPage command result for an in-extension navigation

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandProviderContext.cs

@@ -2,6 +2,8 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using Microsoft.CommandPalette.Extensions;
+
 namespace Microsoft.CmdPal.UI.ViewModels;
 
 public static class CommandProviderContext
@@ -13,6 +15,8 @@ private sealed class EmptyCommandProviderContext : ICommandProviderContext
         public string ProviderId => "<EMPTY>";
 
         public bool SupportsPinning => false;
+
+        public ICommandItem? GetCommandItem(string id) => null;
     }
 }
 
@@ -21,4 +25,6 @@ public interface ICommandProviderContext
     string ProviderId { get; }
 
     bool SupportsPinning { get; }
+
+    ICommandItem? GetCommandItem(string id);
 }

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandProviderWrapper.cs

@@ -22,6 +22,8 @@ public sealed class CommandProviderWrapper : ICommandProviderContext
 
     private readonly ExtensionObject<ICommandProvider> _commandProvider;
 
+    private readonly ICommandProvider4? _commandProvider4;
+
     private readonly TaskScheduler _taskScheduler;
 
     private readonly ICommandProviderCache? _commandProviderCache;
@@ -59,6 +61,7 @@ public CommandProviderWrapper(ICommandProvider provider, TaskScheduler mainThrea
         // This ctor is only used for in-proc builtin commands. So the Unsafe!
         // calls are pretty dang safe actually.
         _commandProvider = new(provider);
+        _commandProvider4 = provider as ICommandProvider4;
         _taskScheduler = mainThread;
         TopLevelPageContext = new(this, _taskScheduler);
 
@@ -69,6 +72,7 @@ public CommandProviderWrapper(ICommandProvider provider, TaskScheduler mainThrea
         _commandProvider.Unsafe!.ItemsChanged += CommandProvider_ItemsChanged;
 
         isValid = true;
+        SupportsPinning = _commandProvider4 is not null;
         Id = provider.Id;
         DisplayName = provider.DisplayName;
         Icon = new(provider.Icon);
@@ -102,6 +106,7 @@ public CommandProviderWrapper(IExtensionWrapper extension, TaskScheduler mainThr
         }
 
         _commandProvider = new(provider);
+        _commandProvider4 = provider as ICommandProvider4;
 
         try
         {
@@ -123,6 +128,7 @@ public CommandProviderWrapper(IExtensionWrapper extension, TaskScheduler mainThr
         }
 
         isValid = true;
+        SupportsPinning = _commandProvider4 is not null;
     }
 
     private ProviderSettings GetProviderSettings(SettingsModel settings)
@@ -182,12 +188,9 @@ public async Task LoadTopLevelCommands(IServiceProvider serviceProvider)
             }
 
             ICommandItem[] pinnedCommands = [];
-            ICommandProvider4? four = null;
-            if (model is ICommandProvider4 definitelyFour)
+            var four = _commandProvider4;
+            if (four is not null)
             {
-                four = definitelyFour; // stash this away so we don't need to QI again
-                SupportsPinning = true;
-
                 // Load pinned commands from saved settings
                 pinnedCommands = LoadPinnedCommands(four, providerSettings);
             }
@@ -483,6 +486,25 @@ public void UnpinDockBand(string commandId, IServiceProvider serviceProvider)
 
     public ICommandProviderContext GetProviderContext() => this;
 
+    public ICommandItem? GetCommandItem(string id)
+    {
+        if (string.IsNullOrWhiteSpace(id))
+        {
+            return null;
+        }
+
+        try
+        {
+            return _commandProvider4?.GetCommandItem(id);
+        }
+        catch (Exception e)
+        {
+            Logger.LogError($"Failed to load command item {id} from provider {ProviderId}: {e.Message}");
+        }
+
+        return null;
+    }
+
     public override bool Equals(object? obj) => obj is CommandProviderWrapper wrapper && isValid == wrapper.isValid;
 
     public override int GetHashCode() => _commandProvider.GetHashCode();

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Messages/GoToPageMessage.cs

@@ -0,0 +1,9 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Microsoft.CommandPalette.Extensions;
+
+namespace Microsoft.CmdPal.UI.ViewModels.Messages;
+
+public record GoToPageMessage(PerformCommandMessage CommandMessage, NavigationMode NavigationMode);

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Messages/PerformCommandMessage.cs

@@ -20,6 +20,10 @@ public record PerformCommandMessage
 
     public bool TransientPage { get; set; }
 
+    public AppExtensionHost? HostOverride { get; set; }
+
+    public ICommandProviderContext? ProviderContextOverride { get; set; }
+
     public PerformCommandMessage(ExtensionObject<ICommand> command)
     {
         Command = command;

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/ShellViewModel.cs

@@ -271,10 +271,10 @@ private void PerformCommand(PerformCommandMessage message)
         // the providerContext that is passed to the new page view-model.
         var isMainPage = command == _rootPage;
 
-        var host = _appHostService.GetHostForCommand(message.Context, CurrentPage.ExtensionHost);
+        var host = message.HostOverride ?? _appHostService.GetHostForCommand(message.Context, CurrentPage.ExtensionHost);
         var providerContext = isMainPage
             ? CommandProviderContext.Empty
-            : _appHostService.GetProviderContextForCommand(message.Context, CurrentPage.ProviderContext);
+            : message.ProviderContextOverride ?? _appHostService.GetProviderContextForCommand(message.Context, CurrentPage.ProviderContext);
 
         _rootPageService.OnPerformCommand(message.Context, CurrentPage.IsRootPage, host);
 
@@ -338,7 +338,7 @@ private void PerformCommand(PerformCommandMessage message)
                 CoreLogger.LogDebug($"Invoking command");
 
                 WeakReferenceMessenger.Default.Send<TelemetryBeginInvokeMessage>();
-                StartInvoke(message, invokable, host);
+                StartInvoke(message, invokable, host, providerContext);
             }
         }
         catch (Exception ex)
@@ -349,7 +349,7 @@ private void PerformCommand(PerformCommandMessage message)
         }
     }
 
-    private void StartInvoke(PerformCommandMessage message, IInvokableCommand invokable, AppExtensionHost? host)
+    private void StartInvoke(PerformCommandMessage message, IInvokableCommand invokable, AppExtensionHost? host, ICommandProviderContext providerContext)
     {
         // TODO GH #525 This needs more better locking.
         lock (_invokeLock)
@@ -362,13 +362,13 @@ private void StartInvoke(PerformCommandMessage message, IInvokableCommand invoka
             {
                 _handleInvokeTask = Task.Run(() =>
                 {
-                    SafeHandleInvokeCommandSynchronous(message, invokable, host);
+                    SafeHandleInvokeCommandSynchronous(message, invokable, host, providerContext);
                 });
             }
         }
     }
 
-    private void SafeHandleInvokeCommandSynchronous(PerformCommandMessage message, IInvokableCommand invokable, AppExtensionHost? host)
+    private void SafeHandleInvokeCommandSynchronous(PerformCommandMessage message, IInvokableCommand invokable, AppExtensionHost? host, ICommandProviderContext providerContext)
     {
         // Telemetry: Track command execution time and success
         var stopwatch = System.Diagnostics.Stopwatch.StartNew();
@@ -386,7 +386,7 @@ private void SafeHandleInvokeCommandSynchronous(PerformCommandMessage message, I
             var result = invokable.Invoke(message.Context);
 
             // But if it did succeed, we need to handle the result.
-            UnsafeHandleCommandResult(result);
+            UnsafeHandleCommandResult(result, host, providerContext, message.TransientPage);
 
             success = true;
             _handleInvokeTask = null;
@@ -412,7 +412,7 @@ private void SafeHandleInvokeCommandSynchronous(PerformCommandMessage message, I
         }
     }
 
-    private void UnsafeHandleCommandResult(ICommandResult? result)
+    private void UnsafeHandleCommandResult(ICommandResult? result, AppExtensionHost? host = null, ICommandProviderContext? providerContext = null, bool transientPage = false)
     {
         if (result is null)
         {
@@ -447,6 +447,20 @@ private void UnsafeHandleCommandResult(ICommandResult? result)
                     break;
                 }
 
+            case CommandResultKind.GoToPage:
+                {
+                    if (result.Args is IGoToPageArgs a)
+                    {
+                        HandleGoToPage(a, host, providerContext, transientPage);
+                    }
+                    else
+                    {
+                        CoreLogger.LogError("Invalid arguments for CommandResultKind.GoToPage");
+                    }
+
+                    break;
+                }
+
             case CommandResultKind.Hide:
                 {
                     // Keep this page open, but hide the palette.
@@ -475,14 +489,67 @@ private void UnsafeHandleCommandResult(ICommandResult? result)
                     if (result.Args is IToastArgs a)
                     {
                         WeakReferenceMessenger.Default.Send<ShowToastMessage>(new(a.Message));
-                        UnsafeHandleCommandResult(a.Result);
+                        UnsafeHandleCommandResult(a.Result, host, providerContext, transientPage);
                     }
 
                     break;
                 }
         }
     }
 
+    private void HandleGoToPage(IGoToPageArgs args, AppExtensionHost? host, ICommandProviderContext? providerContext, bool transientPage)
+    {
+        if (providerContext is null)
+        {
+            CoreLogger.LogWarning($"Unable to navigate to page '{args.PageId}' because no command provider context was available.");
+            host?.Log($"Unable to navigate to page '{args.PageId}' because no command provider context was available.");
+            return;
+        }
+
+        if (string.IsNullOrWhiteSpace(args.PageId))
+        {
+            CoreLogger.LogWarning("Unable to navigate to a page because the requested page id was empty.");
+            host?.Log("Unable to navigate to a page because the requested page id was empty.");
+            return;
+        }
+
+        ICommandItem? targetItem;
+        try
+        {
+            // Resolve the target command item before we hop onto the UI thread.
+            // ICommandProvider4.GetCommandItem may need to materialize a dynamic
+            // command by id, and we do not want that provider work to block frame
+            // navigation or input processing.
+            targetItem = providerContext.GetCommandItem(args.PageId);
+        }
+        catch (Exception ex)
+        {
+            CoreLogger.LogError($"Failed to retrieve page '{args.PageId}' from provider '{providerContext.ProviderId}'.", ex);
+            host?.Log($"Failed to retrieve page '{args.PageId}' from provider '{providerContext.ProviderId}': {ex.Message}");
+            return;
+        }
+
+        if (targetItem?.Command is not { } targetCommand)
+        {
+            CoreLogger.LogWarning($"Provider '{providerContext.ProviderId}' could not supply a command for page '{args.PageId}'.");
+            host?.Log($"Provider '{providerContext.ProviderId}' could not supply a command for page '{args.PageId}'.");
+            return;
+        }
+
+        var performMessage = new PerformCommandMessage(new ExtensionObject<ICommand>(targetCommand), new ExtensionObject<ICommandItem>(targetItem))
+        {
+            // Preserve the original extension identity across the deferred
+            // GoBack/GoHome + follow-up command sequence. By the time the
+            // follow-up PerformCommandMessage runs, CurrentPage may already be
+            // pointing at the page we navigated back to.
+            HostOverride = host,
+            ProviderContextOverride = providerContext,
+            TransientPage = transientPage,
+        };
+
+        WeakReferenceMessenger.Default.Send(new GoToPageMessage(performMessage, args.NavigationMode));
+    }
+
     public void GoHome(bool withAnimation = true, bool focusSearch = true)
     {
         _rootPageService.GoHome();
@@ -496,7 +563,7 @@ public void GoBack(bool withAnimation = true, bool focusSearch = true)
 
     public void Receive(HandleCommandResultMessage message)
     {
-        UnsafeHandleCommandResult(message.Result.Unsafe);
+        UnsafeHandleCommandResult(message.Result.Unsafe, CurrentPage.ExtensionHost, CurrentPage.ProviderContext, _currentlyTransient);
     }
 
     public void Receive(WindowHiddenMessage message)
@@ -528,6 +595,7 @@ public void CancelNavigation()
 
     public void Dispose()
     {
+        WeakReferenceMessenger.Default.UnregisterAll(this);
         _handleInvokeTask?.Dispose();
         _navigationCts?.Dispose();
 

src/modules/cmdpal/Microsoft.CmdPal.UI/Pages/ShellPage.xaml.cs

@@ -46,6 +46,7 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
     IRecipient<SettingsWindowClosedMessage>,
     IRecipient<GoHomeMessage>,
     IRecipient<GoBackMessage>,
+    IRecipient<GoToPageMessage>,
     IRecipient<ShowConfirmationMessage>,
     IRecipient<ShowToastMessage>,
     IRecipient<NavigateToPageMessage>,
@@ -98,6 +99,7 @@ public ShellPage()
 
         WeakReferenceMessenger.Default.Register<GoHomeMessage>(this);
         WeakReferenceMessenger.Default.Register<GoBackMessage>(this);
+        WeakReferenceMessenger.Default.Register<GoToPageMessage>(this);
         WeakReferenceMessenger.Default.Register<ShowConfirmationMessage>(this);
         WeakReferenceMessenger.Default.Register<ShowToastMessage>(this);
         WeakReferenceMessenger.Default.Register<NavigateToPageMessage>(this);
@@ -212,6 +214,26 @@ public void Receive(ShowToastMessage message)
         });
     }
 
+    public void Receive(GoToPageMessage message)
+    {
+        _ = DispatcherQueue.TryEnqueue(() =>
+        {
+            if (_isDisposed)
+            {
+                return;
+            }
+
+            try
+            {
+                HandleGoToPageOnUiThread(message);
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError("Failed to handle GoToPage message", ex);
+            }
+        });
+    }
+
     public void Receive(ShowPinToDockDialogMessage message)
     {
         DispatcherQueue.TryEnqueue(async () =>
@@ -472,6 +494,47 @@ private void SummonOnUiThread(HotkeySummonMessage message)
 
     public void Receive(GoBackMessage message) => _ = DispatcherQueue.TryEnqueue(() => GoBack(message.WithAnimation, message.FocusSearch));
 
+    private void HandleGoToPageOnUiThread(GoToPageMessage message)
+    {
+        switch (message.NavigationMode)
+        {
+            case NavigationMode.GoHome:
+                // GoToPage is composite: go home first, then run the target command.
+                // Queue the second step so CurrentPage can update after navigation.
+                GoHome(message.CommandMessage.WithAnimation, focusSearch: false);
+                _ = _queue.TryEnqueue(() => SafeSendGoToPageCommand(message.CommandMessage));
+                return;
+
+            case NavigationMode.GoBack:
+                // Same idea as GoHome: go back first, then run the target command;
+                // TODO: This is consistent with the other modes, but I wonder if we should instead try to be smarter
+                //   and see if the target page is already in the back stack, and if so just go back to it.
+                //   That might be a nicer experience, but it also might be more complex to implement, at least with
+                //   parameterized pages.
+                GoBack(message.CommandMessage.WithAnimation, focusSearch: false);
+                _ = _queue.TryEnqueue(() => SafeSendGoToPageCommand(message.CommandMessage));
+                return;
+
+            case NavigationMode.Push:
+            default:
+                // Push has no rewind step, so we can run the target command now.
+                SafeSendGoToPageCommand(message.CommandMessage);
+                return;
+        }
+
+        void SafeSendGoToPageCommand(PerformCommandMessage commandMessage)
+        {
+            try
+            {
+                WeakReferenceMessenger.Default.Send(commandMessage);
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError("Failed to dispatch deferred GoToPage command", ex);
+            }
+        }
+    }
+
     private void GoBack(bool withAnimation = true, bool focusSearch = true)
     {
         HideDetails();