Add path-specific GitHub Copilot instructions for .NET MAUI Templates

.github/copilot-instructions/templates.yml

@@ -0,0 +1,94 @@
+# Copilot instructions for working with .NET MAUI Templates
+# This file provides specific guidance when modifying template files in src/Templates/
+
+# Apply these instructions only to files in the Templates directory
+applicability:
+  paths:
+    - 'src/Templates/**'
+
+instructions: |
+  # Working with .NET MAUI Templates
+
+  When modifying files in the `src/Templates/` directory, you must follow special template semantics and conventions to ensure the templates work correctly when users create new projects.
+
+  ## Template Conditional Compilation Directives
+
+  Templates use special comment markers to control how preprocessor directives are processed during template instantiation:
+
+  ### Platform-Specific Directives (Build-Time)
+
+  Platform-specific `#if` directives (like `#if WINDOWS`, `#if ANDROID`, `#if IOS`, `#if MACCATALYST`) must be wrapped with `//-:cnd:noEmit` and `//+:cnd:noEmit` markers:
+
+  ```csharp
+  //-:cnd:noEmit
+  #if WINDOWS
+      // Windows-specific code
+  #endif
+  //+:cnd:noEmit
+  ```
+
+  **Why?** These markers tell the template engine to preserve these directives in the generated code exactly as-is, so they will be evaluated at compile-time when the user builds their project.
+
+  **Examples:**
+  ```csharp
+  //-:cnd:noEmit
+  #if DEBUG
+      builder.Logging.AddDebug();
+  #endif
+  //+:cnd:noEmit
+
+  //-:cnd:noEmit
+  #if IOS || MACCATALYST
+      handlers.AddHandler<CollectionView, CollectionViewHandler2>();
+  #endif
+  //+:cnd:noEmit
+
+  //-:cnd:noEmit
+  #if WINDOWS
+      Microsoft.Maui.Controls.Handlers.Items.CollectionViewHandler.Mapper.AppendToMapping(
+          "KeyboardAccessibleCollectionView", 
+          (handler, view) => { /* ... */ });
+  #endif
+  //+:cnd:noEmit
+  ```
+
+  ### Template Parameter Directives (Template-Time)
+
+  Template parameter directives (like `#if (IncludeSampleContent)`) do NOT use the `//-:cnd:noEmit` markers:
+
+  ```csharp
+  #if (IncludeSampleContent)
+  using CommunityToolkit.Maui;
+  #endif
+  ```
+
+  **Why?** These directives are evaluated when the template is instantiated (when user runs `dotnet new maui`), not when the code is compiled.
+
+  ## Template Naming Conventions
+
+  - Template project names use placeholders like `MauiApp._1` which get replaced with the user's actual project name
+  - Namespaces follow the same pattern: `namespace MauiApp._1;`
+  - These will be transformed to the user's chosen project name during template instantiation
+
+  ## Files to Exclude from Template Changes
+
+  Never modify auto-generated files in templates:
+  - `cgmanifest.json` - Auto-generated component governance manifest
+  - `templatestrings.json` - Auto-generated localization file
+
+  These files are regenerated during the build process and should not be manually edited.
+
+  ## Template Testing
+
+  When making changes to templates:
+  1. Build the template project: `dotnet build src/Templates/src/Microsoft.Maui.Templates.csproj`
+  2. For comprehensive testing, use the `build.ps1` script in the Templates directory to pack, install, and test the template
+  3. Verify the generated project compiles for all target platforms
+
+  ## Quick Reference
+
+  | Directive Type | Wrapper Needed | Example |
+  |---|---|---|
+  | Platform-specific (`#if WINDOWS`, `#if ANDROID`, etc.) | ✅ Yes - use `//-:cnd:noEmit` | Build-time platform detection |
+  | Debug mode (`#if DEBUG`) | ✅ Yes - use `//-:cnd:noEmit` | Build configuration |
+  | Template parameters (`#if (IncludeSampleContent)`) | ❌ No | Template instantiation options |

src/Templates/src/templates/maui-mobile/AppShell.xaml

@@ -47,8 +47,8 @@
                 SegmentWidth="40" SegmentHeight="40">
                 <sf:SfSegmentedControl.ItemsSource>
                     <x:Array Type="{x:Type sf:SfSegmentItem}">
-                        <sf:SfSegmentItem ImageSource="{StaticResource IconLight}"/>
-                        <sf:SfSegmentItem ImageSource="{StaticResource IconDark}"/>
+                        <sf:SfSegmentItem ImageSource="{StaticResource IconLight}" SemanticProperties.Description="Light mode"/>
+                        <sf:SfSegmentItem ImageSource="{StaticResource IconDark}" SemanticProperties.Description="Dark mode"/>
                     </x:Array>
                 </sf:SfSegmentedControl.ItemsSource>
             </sf:SfSegmentedControl>

src/Templates/src/templates/maui-mobile/AppShell.xaml.cs

@@ -13,6 +13,9 @@ public AppShell()
 #if (IncludeSampleContent)
 		var currentTheme = Application.Current!.RequestedTheme;		
 		ThemeSegmentedControl.SelectedIndex = currentTheme == AppTheme.Light ? 0 : 1;
+#endif
+#if ANDROID || WINDOWS
+		SemanticProperties.SetDescription(ThemeSegmentedControl, "Theme selection");
 #endif
 	}
 #if (IncludeSampleContent)

src/Templates/src/templates/maui-mobile/Data/TagRepository.cs

@@ -200,6 +200,12 @@ public async Task<int> SaveItemAsync(Tag item, int projectID)
 		await Init();
 		await SaveItemAsync(item);
 
+		var isAssociated = await IsAssociated(item, projectID);
+		if (isAssociated)
+		{
+			return 0; // No need to save again if already associated
+		}
+
 		await using var connection = new SqliteConnection(Constants.DatabasePath);
 		await connection.OpenAsync();
 
@@ -212,6 +218,32 @@ public async Task<int> SaveItemAsync(Tag item, int projectID)
 		return await saveCmd.ExecuteNonQueryAsync();
 	}
 
+	/// <summary>
+	/// Checks if a tag is already associated with a specific project.
+	/// </summary>
+	/// <param name="item">The tag to save.</param>
+	/// <param name="projectID">The ID of the project.</param>
+	/// <returns>If tag is already associated with this project</returns>
+	async Task<bool> IsAssociated(Tag item, int projectID)
+	{
+		await Init();
+
+		await using var connection = new SqliteConnection(Constants.DatabasePath);
+		await connection.OpenAsync();
+
+		// First check if the association already exists
+		var checkCmd = connection.CreateCommand();
+		checkCmd.CommandText = @"
+			SELECT COUNT(*) FROM ProjectsTags 
+			WHERE ProjectID = @projectID AND TagID = @tagID";
+		checkCmd.Parameters.AddWithValue("@projectID", projectID);
+		checkCmd.Parameters.AddWithValue("@tagID", item.ID);
+
+		int existingCount = Convert.ToInt32(await checkCmd.ExecuteScalarAsync());
+
+		return existingCount != 0;
+	}
+
 	/// <summary>
 	/// Deletes a tag from the database.
 	/// </summary>

src/Templates/src/templates/maui-mobile/MauiProgram.cs

@@ -18,14 +18,25 @@ public static MauiApp CreateMauiApp()
 #if (IncludeSampleContent)
 			.UseMauiCommunityToolkit()
 			.ConfigureSyncfusionToolkit()
+//-:cnd:noEmit
 			.ConfigureMauiHandlers(handlers =>
 			{
-//-:cnd:noEmit
-#if IOS || MACCATALYST
-				handlers.AddHandler<Microsoft.Maui.Controls.CollectionView, Microsoft.Maui.Controls.Handlers.Items2.CollectionViewHandler2>();
+#if WINDOWS
+				Microsoft.Maui.Controls.Handlers.Items.CollectionViewHandler.Mapper.AppendToMapping("KeyboardAccessibleCollectionView", (handler, view) =>
+				{
+					handler.PlatformView.SingleSelectionFollowsFocus = false;
+				});
+
+            	Microsoft.Maui.Handlers.ContentViewHandler.Mapper.AppendToMapping(nameof(Pages.Controls.CategoryChart), (handler, view) =>
+            	{
+	                if (view is Pages.Controls.CategoryChart && handler.PlatformView is ContentPanel contentPanel)
+                	{
+                    	contentPanel.IsTabStop = true;
+                	}
+            	});
 #endif
+            })
 //+:cnd:noEmit
-			})
 #endif
 			.ConfigureFonts(fonts =>
 			{

src/Templates/src/templates/maui-mobile/PageModels/MainPageModel.cs

@@ -35,6 +35,9 @@ public partial class MainPageModel : ObservableObject, IProjectTaskPageModel
 	[ObservableProperty]
 	private string _today = DateTime.Now.ToString("dddd, MMM d");
 
+	[ObservableProperty]
+	private Project? selectedProject;
+
 	public bool HasCompletedTasks
 		=> Tasks?.Any(t => t.IsCompleted) ?? false;
 

src/Templates/src/templates/maui-mobile/PageModels/ProjectDetailPageModel.cs

@@ -1,6 +1,8 @@
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using MauiApp._1.Models;
+using System.Collections.ObjectModel;
+using System.Windows.Input;
 
 namespace MauiApp._1.PageModels;
 
@@ -34,6 +36,8 @@ public partial class ProjectDetailPageModel : ObservableObject, IQueryAttributab
 	[ObservableProperty]
 	private List<Tag> _allTags = [];
 
+	public IList<object> SelectedTags { get; set; } = new List<object>();
+
 	[ObservableProperty]
 	private IconData _icon;
 
@@ -135,6 +139,10 @@ private async Task LoadData(int id)
 			foreach (var tag in allTags)
 			{
 				tag.IsSelected = _project.Tags.Any(t => t.ID == tag.ID);
+				if (tag.IsSelected)
+				{
+					SelectedTags.Add(tag);
+				}
 			}
 			AllTags = new(allTags);
 		}
@@ -156,7 +164,6 @@ private async Task TaskCompleted(ProjectTask task)
 		OnPropertyChanged(nameof(HasCompletedTasks));
 	}
 
-
 	[RelayCommand]
 	private async Task Save()
 	{
@@ -174,14 +181,11 @@ private async Task Save()
 		_project.Icon = Icon.Icon ?? FluentUI.ribbon_24_regular;
 		await _projectRepository.SaveItemAsync(_project);
 
-		if (_project.IsNullOrNew())
+		foreach (var tag in AllTags)
 		{
-			foreach (var tag in AllTags)
+			if (tag.IsSelected)
 			{
-				if (tag.IsSelected)
-				{
-					await _tagRepository.SaveItemAsync(tag, _project.ID);
-				}
+				await _tagRepository.SaveItemAsync(tag, _project.ID);
 			}
 		}
 
@@ -236,7 +240,7 @@ private Task NavigateToTask(ProjectTask task) =>
 		Shell.Current.GoToAsync($"task?id={task.ID}");
 
 	[RelayCommand]
-	private async Task ToggleTag(Tag tag)
+	internal async Task ToggleTag(Tag tag)
 	{
 		tag.IsSelected = !tag.IsSelected;
 
@@ -253,6 +257,7 @@ private async Task ToggleTag(Tag tag)
 		}
 
 		AllTags = new(AllTags);
+		SemanticScreenReader.Announce($"{tag.Title} {(tag.IsSelected ? "selected" : "unselected")}");
 	}
 
 	[RelayCommand]
@@ -269,4 +274,34 @@ private async Task CleanTasks()
 		OnPropertyChanged(nameof(HasCompletedTasks));
 		await AppShell.DisplayToastAsync("All cleaned up!");
 	}
+
+	[RelayCommand]
+	private async Task SelectionChanged(object parameter)
+	{
+		if (parameter is IEnumerable<object> enumerableParameter)
+		{
+			var currentSelection = enumerableParameter.OfType<Tag>().ToList();
+			var previousSelection = AllTags.Where(t => t.IsSelected).ToList();
+
+			// Handle newly selected tags
+			foreach (var tag in currentSelection.Except(previousSelection))
+			{
+				tag.IsSelected = true;
+				if (!_project.IsNullOrNew())
+				{
+					await _tagRepository.SaveItemAsync(tag, _project.ID);
+				}
+			}
+
+			// Handle deselected tags
+			foreach (var tag in previousSelection.Except(currentSelection))
+			{
+				tag.IsSelected = false;
+				if (!_project.IsNullOrNew())
+				{
+					await _tagRepository.DeleteItemAsync(tag, _project.ID);
+				}
+			}
+		}
+	}
 }

src/Templates/src/templates/maui-mobile/PageModels/ProjectListPageModel.cs

@@ -1,4 +1,3 @@
-#nullable disable
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using MauiApp._1.Data;
@@ -14,6 +13,9 @@ public partial class ProjectListPageModel : ObservableObject
 	[ObservableProperty]
 	private List<Project> _projects = [];
 
+	[ObservableProperty]
+	private Project? selectedProject;
+
 	public ProjectListPageModel(ProjectRepository projectRepository)
 	{
 		_projectRepository = projectRepository;
@@ -26,8 +28,8 @@ private async Task Appearing()
 	}
 
 	[RelayCommand]
-	Task NavigateToProject(Project project)
-		=> Shell.Current.GoToAsync($"project?id={project.ID}");
+	Task? NavigateToProject(Project project)
+		=> project is null ? Task.CompletedTask : Shell.Current.GoToAsync($"project?id={project.ID}");
 
 	[RelayCommand]
 	async Task AddProject()