WinUI App

Use this skill for WinUI 3 and Windows App SDK work that needs grounded setup guidance, app bootstrap, modern Windows UX decisions, or concrete implementation patterns.

Required Flow

1. Classify the task as environment/setup, new-app bootstrap, design, implementation, review, or troubleshooting.
2. If the task is about preparing a machine for WinUI, auditing readiness, or creating a brand new app, start with the bundled setup-and-scaffold flow in this skill before broader design, implementation, or troubleshooting work:
   • Pick the app name when the request is for a new app.
   • Use the exact name the user gave when it is already a safe folder name.
   • If the user did not give a name, derive a short PascalCase name from the request and state what you chose.
   • Create the project in the user's current workspace unless they asked for another location.
   • Do not use --force unless the user explicitly asked to overwrite existing files.
   • Run the bundled WinGet configuration from the skill directory so the relative path stays exactly config.yaml:

winget configure -f config.yaml --accept-configuration-agreements --disable-interactivity

• Treat the configuration as intended to enable Developer Mode, install or update Visual Studio Community 2026, and install the Managed Desktop, Universal, and Windows App SDK C# components needed for WinUI development.
• Assess the configuration result before continuing. Continue on success. If it fails, inspect the output instead of guessing. If the winui template is already available and the toolchain is usable, note the partial failure and continue. If prerequisites are still missing, stop and report the blocker clearly.
• Verify the template is available before scaffolding:

dotnet new list winui

• For diagnostics-only environment requests, explain that the bundled bootstrap may change the machine and get confirmation before running it. If the user declines changes, use the manual verification guidance in references/foundation-environment-audit-and-remediation.md and summarize readiness under present, missing, uncertain, and recommended optional tools.
• For a brand new app, scaffold with dotnet new winui -o <name>. Add template options only when the user asked for them. Supported options: -f|--framework net10.0|net9.0|net8.0, -slnx|--use-slnx, -cpm|--central-pkg-mgmt, -mvvm|--use-mvvm, -imt|--include-mvvm-toolkit, -un|--unpackaged, -nsf|--no-solution-file, --force. Do not invent unsupported flags. If the user asks for packaged behavior, pass --unpackaged false. Otherwise keep the template default.
• Verify a new scaffold by confirming the expected project file exists and running dotnet build against the generated .csproj.
• Launch a newly scaffolded app through the correct path for its actual packaging model and confirm there is a real top-level window instead of relying only on the launcher process exit code.

1. Read references/_sections.md, then load only the reference files that match the task.
2. Make the packaging model explicit before creating or refactoring the app. Default to packaged for Store-like product workflows and Visual Studio deploy/F5 flows. Default to unpackaged when the user expects repeatable CLI build-and-run loops or direct .exe launches after each change.
3. When the task is an opaque XAML compiler failure such as MSB3073 or XamlCompiler.exe, read references/foundation-template-first-recovery.md and simplify back toward the current dotnet new winui scaffold for the chosen packaging model before inventing custom recovery structure.

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