Add Microsoft-maintained winui plugin (external reference) (#1686)

* Add winui plugin from microsoft/win-dev-skills

Adds the Microsoft-maintained WinUI 3 development plugin as an external
plugin reference. This is a Microsoft-managed repository so it qualifies
for the external-plugin policy exception in CONTRIBUTING.md.

The plugin provides agents and skills for WinUI 3 app development:
new app scaffolding, framework migration (WPF, WinForms, Electron,
Tauri, Flutter to WinUI 3), MSIX packaging, code signing, UI
automation testing, and Windows App SDK guidance.

Source: https://github.com/microsoft/win-dev-skills

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Remove winui3-development plugin (replaced by external winui plugin)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Nikola Metulev <nmetulev@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/plugin/marketplace.json

@@ -708,10 +708,33 @@
       }
     },
     {
-      "name": "winui3-development",
+      "name": "winui",
-      "source": "winui3-development",
+      "description": "Agents and skills for WinUI 3 app development. Create new WinUI 3 desktop apps, convert from other frameworks (WPF, WinForms, Electron, Tauri, Flutter) to WinUI 3, or add features to existing WinUI 3 applications. Includes MSIX packaging, code signing, UI automation testing, and Windows App SDK guidance.",
-      "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": "0.3.0",
-      "version": "1.2.0"
+      "author": {
+        "name": "Microsoft",
+        "url": "https://www.microsoft.com"
+      },
+      "homepage": "https://github.com/microsoft/win-dev-skills",
+      "keywords": [
+        "windows",
+        "winui",
+        "winui3",
+        "xaml",
+        "windows-app-sdk",
+        "msix",
+        "packaging",
+        "desktop",
+        "wpf-migration",
+        "electron-migration"
+      ],
+      "license": "MIT",
+      "repository": "https://github.com/microsoft/win-dev-skills",
+      "source": {
+        "source": "github",
+        "repo": "microsoft/win-dev-skills",
+        "path": "plugins/winui"
+      }
     }
   ]
 }

plugins/external.json

@@ -305,5 +305,34 @@
       "source": "github",
       "repo": "microsoft/Build-CLI"
     }
+  },
+  {
+    "name": "winui",
+    "description": "Agents and skills for WinUI 3 app development. Create new WinUI 3 desktop apps, convert from other frameworks (WPF, WinForms, Electron, Tauri, Flutter) to WinUI 3, or add features to existing WinUI 3 applications. Includes MSIX packaging, code signing, UI automation testing, and Windows App SDK guidance.",
+    "version": "0.3.0",
+    "author": {
+      "name": "Microsoft",
+      "url": "https://www.microsoft.com"
+    },
+    "homepage": "https://github.com/microsoft/win-dev-skills",
+    "keywords": [
+      "windows",
+      "winui",
+      "winui3",
+      "xaml",
+      "windows-app-sdk",
+      "msix",
+      "packaging",
+      "desktop",
+      "wpf-migration",
+      "electron-migration"
+    ],
+    "license": "MIT",
+    "repository": "https://github.com/microsoft/win-dev-skills",
+    "source": {
+      "source": "github",
+      "repo": "microsoft/win-dev-skills",
+      "path": "plugins/winui"
+    }
   }
 ]

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

@@ -1,32 +0,0 @@
-{
-  "name": "winui3-development",
-  "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"
-  },
-  "repository": "https://github.com/github/awesome-copilot",
-  "license": "MIT",
-  "keywords": [
-    "winui",
-    "winui3",
-    "windows-app-sdk",
-    "xaml",
-    "desktop",
-    "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

@@ -1,48 +0,0 @@
-# WinUI 3 Development Plugin
-
-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
-
-```bash
-# Using Copilot CLI
-copilot plugin install winui3-development@awesome-copilot
-```
-
-## What's Included
-
-### Commands (Slash Commands)
-
-| 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
-
-| Agent | Description |
-|-------|-------------|
-| `winui3-expert` | Expert agent for WinUI 3 and Windows App SDK development. Prevents common UWP-to-WinUI 3 API mistakes, guides XAML controls, MVVM patterns, windowing, threading, app lifecycle, dialogs, and deployment. |
-
-## Key Features
-
-- **UWP→WinUI 3 API migration rules** — prevents the most common code generation mistakes
-- **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 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
-
-This plugin is part of [Awesome Copilot](https://github.com/github/awesome-copilot), a community-driven collection of GitHub Copilot extensions.
-
-## License
-
-MIT