/winui-setup

name: winui-setup
description: "Install and verify the prerequisites the win-dev-skills WinUI 3 toolchain depends on — .NET SDK 8.0.100+, WinApp CLI 0.6+, and Developer Mode. Use only when the user explicitly asks to set up or repair the toolchain. Do not invoke automatically when another skill reports a missing prerequisite; tell the user what is missing and ask them to invoke this skill."

Purpose

Install and verify the prerequisites every other `winui-*` skill assumes. WinApp CLI 0.6 owns WinUI template discovery and installation through `winapp new`; **do not install the template pack separately**.

> [!IMPORTANT] > Run this skill only when the user explicitly asks to set up or repair the toolchain. If it is loaded without an explicit request, do not run checks or installations; explain what the skill changes and wait for confirmation.

This skill is idempotent: detect everything first, install or upgrade only what is needed, and print one final summary.

Steps

Detect everything

Run these checks together so the user sees the full state before anything changes:

$minimumDotNet = [version]'8.0.100'
$minimumWinApp = [version]'0.6.0'

# .NET SDK — project-mode winapp run requires SDK 8.0.100+
$dotnetSdks = @(& dotnet --list-sdks 2>$null) | ForEach-Object {
    $text = ($_ -replace ' \[.*$','').Trim()
    $parsed = $null
    if ([version]::TryParse(($text -split '-')[0], [ref]$parsed)) { $parsed }
}
$dotnetVersion = $dotnetSdks |
    Where-Object { $_ -ge $minimumDotNet } |
    Sort-Object -Descending |
    Select-Object -First 1
$dotnetOk = $null -ne $dotnetVersion

# WinApp CLI — require 0.6+ for winapp new, find-ui, and project-mode run
$winappCmd = Get-Command winapp -ErrorAction SilentlyContinue
$winappVersion = $null
if ($winappCmd) {
    foreach ($line in @(& winapp --version 2>$null)) {
        $match = [regex]::Match(
            [string]$line,
            '^\s*v?(?<version>\d+\.\d+\.\d+)(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?\s*$'
        )
        if ($match.Success) {
            $parsed = $null
            if ([version]::TryParse($match.Groups['version'].Value, [ref]$parsed)) {
                $winappVersion = $parsed
            }
        }
    }
}
$winappOk = $winappVersion -ge $minimumWinApp

# Developer Mode
$devModeOk = ((Get-ItemProperty `
    -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock' `
    -Name AllowDevelopmentWithoutDevLicense -ErrorAction SilentlyContinue
).AllowDevelopmentWithoutDevLicense) -eq 1

Print a one-shot status table:

.NET SDK >= 8.0.100     [OK] found 10.0.100
WinApp CLI >= 0.6.0     [!] found 0.5.1 — will upgrade
Developer Mode          [X] disabled — needs admin to enable

Install what's missing

.NET SDK

Only when no SDK at or above `8.0.100` was found:

winget install --id Microsoft.DotNet.SDK.10 --exact --silent --accept-package-agreements --accept-source-agreements

Do not install another SDK when 8.0.100+, 9.x, or 10.x is already present.

WinApp CLI

If `winapp` is missing, install it. If it is present but below 0.6.0, try to upgrade it. Skip both commands when the installed version already meets the minimum:

# When winapp is missing
winget install --id Microsoft.WinAppCli --exact --silent --accept-package-agreements --accept-source-agreements

# When winapp is present but older than 0.6.0
winget upgrade --id Microsoft.WinAppCli --exact --silent --accept-package-agreements --accept-source-agreements

Refresh PATH after any winget install or upgrade:

$env:Path = [Environment]::GetEnvironmentVariable('Path','Machine') + ';' +
            [Environment]::GetEnvironmentVariable('Path','User')

Run the version detection again. If the result is still below `0.6.0`, report the actual version and mark setup failed; do not continue with old command fallbacks.

> `winapp new` installs the official `Microsoft.WindowsAppSDK.WinUI.CSharp.Templates` pack on demand and can update it with `--template-version latest`. Do not run `dotnet new install` during setup.

Developer Mode (ask first)

Developer Mode requires admin elevation. **Ask the user before triggering UAC.** Only if they agree, elevate this one operation:

Start-Process powershell -Verb RunAs -ArgumentList @(
    '-NoProfile','-Command',
    "New-Item -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock' -Force | Out-Null; " +
    "Set-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock' " +
    "-Name AllowDevelopmentWithoutDevLicense -Type DWord -Value 1"
) -Wait

If the user declines or dismisses UAC, continue to the summary and print the command for later use.

Final summary

Always print a single summary:

==== winui-setup summary ====
.NET SDK >= 8.0.100     [>] already present (10.0.100)
WinApp CLI >= 0.6.0     [OK] upgraded to 0.6.0
Developer Mode          [OK] enabled

You're ready. If the current harness exposes the `winui-dev` orchestrator agent, start a fresh session with that agent and ask it to build a WinUI app. Otherwise, start a fresh session in the current harness and ask it to perform the WinUI task; it will load the relevant `winui-*` skills on demand.

For GitHub Copilot CLI, for example:

copilot --agent winui:winui-dev -p "build me a WinUI 3 markdown editor"

Things to NOT do

• Do not install Visual Studio; these skills build and run with `dotnet` and `winapp`.
• Do not install or upgrade the user's AI coding harness; this skill manages Windows/WinUI development prerequisites only.
• Do not install the WinUI template pack separately; `winapp new` owns it in 0.6+.
• Do not elevate the entire session; only the Developer Mode registry write needs admin.
• Do not skip the PATH refresh after a winget install or upgrade.
• Do not trigger UAC without asking the user first.
• Do not silently retry failed installs or accept WinApp CLI