winui-design
Scope: WinUI 3 apps only. The Windows App SDK is not WinUI. A WPF, WinForms, Electron, or other app that references the Windows App SDK (for notifications, packaging, or other APIs) is not a WinUI app; keep its framework and don't apply this skill unless the task is to port it to WinUI 3. A WinUI 3 project has <UseWinUI>true</UseWinUI> or uses Microsoft.UI.Xaml.
Search samples before writing XAML
This workflow requires WinApp CLI 0.7+. Use winapp find-ui for grounded control and sample discovery. Front-load lookups, then code:
winapp find-ui "<focused feature>" # compact matches + scenario IDs
winapp find-ui --id <scenario-id> # full XAML/C# + prerequisite notes
winapp find-ui --id <id-1> --id <id-2> --json # batch, structured output
winapp find-ui --list # browse all default-source scenarios
winapp find-ui "<feature>" --refresh # force a corpus refresh
Default search covers the WinUI Gallery, Windows Community Toolkit, and curated core patterns. Reactor's C#-only/MVU samples are opt-in with --source reactor; use them only for Reactor projects. The Gallery/Toolkit/Reactor corpus is fetched and cached by WinApp CLI, while core patterns work offline.