Getting AI agents to write WinUI apps has been hit-or-miss. Generic agents pull from too much context — mixing WinUI 3 with older UWP patterns, getting MSIX packaging wrong, or generating apps that don’t actually run. The new WinUI agent plugin takes a different approach.
What It Is
A set of open-source agent skills designed specifically for WinUI and Windows App SDK development, compatible with both GitHub Copilot CLI and Claude Code.
Install and run:
# Add the WinUI plugin to GitHub Copilot CLI
/plugin install winui@awesome-copilot
# Run the setup skill to install prerequisites
/winui:winui-setup
Then describe the app you want. The agent handles the rest.
The End-to-End Loop
The skills are built around a complete development loop: scaffold → build → run → test → iterate. What makes this different from just asking a generic agent:
Scaffold correctly — the agent picks the right dotnet new WinUI template, not an older UWP pattern.
Build through the right pipeline — WinUI apps need packaged execution. Generic agents often don’t know this and generate apps that compile but don’t run. The skills handle the packaged execution model correctly.
Interact and validate — if you ask, the agent can interact with the running app to validate functionality, not just check that the build succeeded.
Fix compilation errors automatically — rather than stopping at the first error, the agent recognizes common WinUI failure modes and steers toward working solutions.
Beyond the basics, the skills also handle higher-level polish: accessibility audits, code reviews, MSIX packaging.
The Token Efficiency Design
Building in rich WinUI context up front would make every turn expensive. Instead, the skills are paired with purpose-built tools that give the agent ground-truth answers on demand — only pulling in specific reference data when the agent needs it, not loading entire documentation pages preemptively.
The result: agents that know WinUI deeply without the token overhead of loading everything every turn.
Supported Features
The skills handle: XAML and Fluent Design, MVVM, MSIX packaging, code signing, Store submission, accessibility, theming, UI automation. That covers most of the surface area where agents typically get stuck.
Original post: Introducing WinUI agent plugin for GitHub Copilot and Claude Code
