winui-app

Verify the template with `dotnet new list winui`, then scaffold with `dotnet new winui -o <name>`. Supported options include framework choice, MVVM, central package management, and unpackaged mode. Build the generated project and launch it to confirm a real window appears.

You need Windows 10 build 17763 or later, Visual Studio with the Managed Desktop, Universal, and Windows App SDK C# components, Windows SDK 10.0.19041.0 or later, and a supported .NET SDK. The bundled WinGet configuration installs these prerequisites automatically.

Choose packaged for Store-like workflows, Visual Studio F5 deployment, and package-identity APIs. Choose unpackaged when you need repeatable CLI build-and-run loops or direct .exe launches. Decide before writing startup, storage, and launch code.

These opaque failures usually come from startup or shared-resource issues rather than the last edited line. Scaffold a fresh comparison app with the same packaging model, diff App.xaml and merged resource dictionaries, and revert toward the template shape incrementally.

Use CommunityToolkit only when built-in WinUI controls and system styling hooks do not cover the need cleanly, such as settings surfaces or segmented controls. Add the smallest package set that solves the problem and document why the built-in alternative was rejected.

Yes, and apps should support both by default using theme-aware resources, system brushes, and WinUI styling hooks instead of hard-coded colors. Single-theme output is treated as an exception requiring an explicit request or product constraint.