WinUI plugin enhancements and add MVVM Toolkit skill (#1643)

* WinUI plugin enhancements and mvvm toolkit skill

* Split mvvm-toolkit skill for slimming

plugins/winui3-development/.github/plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "winui3-development",
-  "description": "WinUI 3 and Windows App SDK development agent, instructions, and migration guide. Prevents common UWP API misuse and guides correct WinUI 3 patterns for desktop Windows apps.",
-  "version": "1.0.0",
+  "description": "End-to-end WinUI 3 and Windows App SDK toolkit: expert agent, coding instructions, UWP-to-WinUI 3 migration guide, MVVM Toolkit reference, plus CLIs for packaging/debugging (winapp) and Microsoft Store publishing (msstore). Covers the full write → package → publish lifecycle for desktop Windows apps and prevents common UWP API misuse.",
+  "version": "1.2.0",
   "author": {
     "name": "Awesome Copilot Community"
   },
@@ -13,12 +13,20 @@
     "windows-app-sdk",
     "xaml",
     "desktop",
-    "windows"
+    "windows",
+    "mvvm",
+    "msix",
+    "microsoft-store"
   ],
   "agents": [
     "./agents/winui3-expert.md"
   ],
   "skills": [
+    "./skills/msstore-cli/",
+    "./skills/mvvm-toolkit-di/",
+    "./skills/mvvm-toolkit-messenger/",
+    "./skills/mvvm-toolkit/",
+    "./skills/winapp-cli/",
     "./skills/winui3-migration-guide/"
   ]
 }

plugins/winui3-development/README.md

@@ -1,6 +1,6 @@
 # WinUI 3 Development Plugin
 
-WinUI 3 and Windows App SDK development agent, instructions, and migration guide. Prevents common UWP API misuse and guides correct WinUI 3 patterns for desktop Windows apps.
+End-to-end WinUI 3 and Windows App SDK toolkit: expert agent, coding instructions, UWP-to-WinUI 3 migration guide, MVVM Toolkit reference, plus CLIs for packaging/debugging (winapp) and Microsoft Store publishing (msstore). Covers the full write → package → publish lifecycle for desktop Windows apps and prevents common UWP API misuse.
 
 ## Installation
 
@@ -15,6 +15,11 @@ copilot plugin install winui3-development@awesome-copilot
 
 | Command | Description |
 |---------|-------------|
+| `/winui3-development:msstore-cli` | Microsoft Store Developer CLI for publishing Windows apps to the Microsoft Store — credentials, app/submission management, package flights, CI/CD publishing |
+| `/winui3-development:mvvm-toolkit` | CommunityToolkit.Mvvm core: source generators (`[ObservableProperty]`, `[RelayCommand]`), base classes, validation, and pitfalls |
+| `/winui3-development:mvvm-toolkit-di` | Wire MVVM Toolkit ViewModels into `Microsoft.Extensions.DependencyInjection` — Generic Host, lifetimes, constructor injection, testing |
+| `/winui3-development:mvvm-toolkit-messenger` | MVVM Toolkit Messenger pub/sub — `WeakReferenceMessenger`, `IRecipient<T>`, `RequestMessage<T>`, channels, lifecycle |
+| `/winui3-development:winapp-cli` | Windows App Development CLI for building, MSIX packaging, debugging-as-packaged, manifests, certificates, signing, and UI automation |
 | `/winui3-development:winui3-migration-guide` | UWP-to-WinUI 3 migration reference with API mappings and before/after code snippets |
 
 ### Agents
@@ -29,8 +34,10 @@ copilot plugin install winui3-development@awesome-copilot
 - **Threading guidance** — DispatcherQueue instead of CoreDispatcher
 - **Windowing patterns** — AppWindow instead of CoreWindow/ApplicationView
 - **Dialog/Picker patterns** — ContentDialog with XamlRoot, pickers with window handle interop
-- **MVVM best practices** — CommunityToolkit.Mvvm, compiled bindings, dependency injection
+- **MVVM best practices** — CommunityToolkit.Mvvm source generators, compiled bindings, dependency injection
 - **Migration checklist** — step-by-step guide for porting UWP apps
+- **MSIX packaging & debugging** — `winapp` CLI for build, run-as-packaged, manifest, cert, and sign workflows
+- **Store publishing** — `msstore` CLI for credentials, submissions, flights, and CI/CD publishing pipelines
 
 ## Source