cmdpal: Support Enter key to submit FormContent (Adaptive Card) inputs

src/modules/cmdpal/Microsoft.CmdPal.UI/Controls/ContentFormControl.xaml.cs

@@ -8,7 +8,9 @@
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Automation;
 using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Input;
 using Microsoft.UI.Xaml.Media;
+using Windows.System;
 
 namespace Microsoft.CmdPal.UI.Controls;
 
@@ -22,6 +24,7 @@ public sealed partial class ContentFormControl : UserControl
     // tree. If this gets GC'ed, then it'll revoke our Action handler, and the
     // form will do seemingly nothing.
     private RenderedAdaptiveCard? _renderedCard;
+    private AdaptiveCard? _adaptiveCard;
 
     public ContentFormViewModel? ViewModel { get => _viewModel; set => AttachViewModel(value); }
 
@@ -95,9 +98,11 @@ private void ViewModel_PropertyChanged(object? sender, System.ComponentModel.Pro
     private void DisplayCard(AdaptiveCardParseResult result)
     {
         _renderedCard = _renderer.RenderAdaptiveCard(result.AdaptiveCard);
+        _adaptiveCard = result.AdaptiveCard;
         ContentGrid.Children.Clear();
         if (_renderedCard.FrameworkElement is not null)
         {
+            _renderedCard.FrameworkElement.KeyDown += OnFormKeyDown;
             ContentGrid.Children.Add(_renderedCard.FrameworkElement);
 
             // Use the Loaded event to ensure we focus after the card is in the visual tree
@@ -276,6 +281,35 @@ private static void FixToggleAccessibilityNames(DependencyObject root)
         return null;
     }
 
+    private void OnFormKeyDown(object sender, KeyRoutedEventArgs e)
+    {
+        if (e.Key != VirtualKey.Enter || _renderedCard == null || _adaptiveCard == null)
+        {
+            return;
+        }
+
+        // Only submit when Enter is pressed inside a single-line TextBox
+        if (e.OriginalSource is TextBox textBox && !textBox.AcceptsReturn)
+        {
+            // Find the first Submit or Execute action on the card
+            IAdaptiveActionElement? submitAction = null;
+            foreach (var action in _adaptiveCard.Actions)
+            {
+                if (action is AdaptiveSubmitAction or AdaptiveExecuteAction)
+                {
+                    submitAction = action;
+                    break;
+                }
+            }
+
+            if (submitAction != null)
+            {
+                e.Handled = true;
+                ViewModel?.HandleSubmit(submitAction, _renderedCard.UserInputs.AsJson());
+            }
+        }
+    }
+
     private void Rendered_Action(RenderedAdaptiveCard sender, AdaptiveActionEventArgs args) =>
         ViewModel?.HandleSubmit(args.Action, args.Inputs.AsJson());
 }