microsoft/win-dev-skills: WinUI 3 Agent Plugin for Copilot, Claude Code, and Codex

What win-dev-skills Is and Why It Exists

Building native Windows apps with WinUI 3 and the Windows App SDK covers a wide surface: XAML and Fluent Design, MVVM patterns, MSIX packaging, code signing, Store submission, accessibility, theming, and UI automation. AI agents working from general web context tend to confuse WinUI 3 with older Windows development stacks like UWP and WPF, missing the packaged execution model and producing code that does not run correctly on current tooling.

win-dev-skills addresses this by packaging WinUI 3 knowledge as an Agent Plugins 1.0 package. It installs as a plugin into GitHub Copilot CLI, Claude Code, or OpenAI Codex and adds a set of skills that cover the end-to-end development inner loop: scaffold, design, build, run, test, package, and ship. The skills use real tools, including winapp and dotnet, to give the agent verified outcomes rather than pattern-matched guesses.

The README states the result explicitly: when you ask Copilot to create a WinUI 3 markdown editor with live preview and a custom title bar, you get working code rather than a mix of WinUI 3 and outdated API calls. The plugin is maintained by Microsoft and is listed on awesome-copilot.

The repository is at v0.x preview status. The README includes a prominent warning that skill names, on-disk layout, agent configuration, analyzer rule IDs, and CLI tool surfaces are all subject to change without notice until v1.0. There is no SemVer commitment in the preview period.

Installing the Plugin Across Five Supported Tools

The plugin supports five agent tools: GitHub Copilot CLI, Claude Code, OpenAI Codex, OpenClaw, and OpenCode. Each has its own install path documented in the README.

For GitHub Copilot CLI, the simplest path is adding the marketplace and installing the winui plugin:

copilot plugin marketplace add microsoft/win-dev-skills
copilot plugin install winui@win-dev-skills

For Claude Code:

claude plugin marketplace add microsoft/win-dev-skills
claude plugin install winui@win-dev-skills

For OpenClaw, the install command uses the explicit marketplace source:

openclaw plugins install winui --marketplace microsoft/win-dev-skills
openclaw gateway restart

The README also documents an Option A for Copilot CLI users: pasting a single prompt into a Copilot session that installs the plugin and sets up all prerequisites in one shot. That path is appropriate for users who want the agent to handle the setup itself.

Once installed, start a new session and run `winui-setup` with /winui-setup to configure the machine. The skill checks and installs prerequisites: Git at 2.54 or higher, .NET SDK at 8.0.100 or higher (with 10.0 recommended), WinApp CLI at 0.6.0 or higher, and Developer Mode enabled. The README is explicit that Visual Studio is not required: these skills build and run entirely through dotnet and winapp.

The Eight Skills and What Each One Does

The plugin exposes eight skills once installed. The README describes their purpose through the development inner loop they cover.

winui-setup configures the developer's machine and verifies prerequisites. winui-scaffold creates a new WinUI 3 project with the correct project structure and MVVM layout using `winapp new`. winui-design handles XAML and Fluent Design guidance, helping the agent produce layouts that match the current WinUI 3 design language rather than older UWP patterns.

winui-build compiles the project through dotnet. winui-run builds and launches the application. winui-test handles UI automation test authoring and execution. winui-package produces a signed MSIX package. winui-ship covers Store submission preparation.

For Codex users, the README notes that the orchestrator agent (winui-dev) is not exposed because Codex does not have an agents concept. The individual skills still function and can be invoked by name. The same applies to OpenClaw and OpenCode: those tools map skills rather than agents, so the orchestrator is not available but the individual skills work.

The README also notes the Windows App SDK XAML compiler bug that was present in older versions: a malformed .xaml file produced no useful diagnostic and the build failed with a cryptic MSB3073 error. This is fixed in Windows App SDK 2.1.3 or later on the 2.x line and 1.8 or later on the 1.x line. The skill set requires updating the Microsoft.WindowsAppSDK NuGet package to the latest version before starting.

What the Preview Status Means for Production Use

The v0.x designation in the README is not a formality. The warning covers skill names, on-disk layout, agent configuration, analyzer rule IDs, and CLI tool surfaces, all of which can change without notice before v1.0. There is no compatibility guarantee between minor versions.

For users who need a stable configuration, the README recommends installing from a release tag rather than the rolling marketplace. The RELEASING.md and CHANGELOG.md files in the repository track what changes between versions, which is useful for evaluating whether an upgrade will break an existing workflow.

The README also states directly that outputs are suggestions, not authoritative answers. This is not specific to the preview status: an agent that generates XAML and C# code for a WinUI 3 app is producing a plausible starting point, not a guaranteed-correct implementation. The skills reduce the rate of wrong-stack errors, but they do not replace testing the generated code against the Windows App SDK documentation.

This is an appropriate tool for developers who are already familiar with WinUI 3 and want agent assistance to speed up the repetitive parts of the inner loop. It is less appropriate for developers who are new to WinUI 3 and plan to ship the agent's output without reviewing it.

How win-dev-skills Compares to Using a General-Purpose AI Agent

A general-purpose AI agent or coding assistant without WinUI 3 context will mix API calls from WinUI 3, UWP, and WPF when answering Windows development questions. The three stacks share a surface-level similarity in XAML syntax but differ significantly in the runtime model, packaging requirements, and available APIs.

win-dev-skills solves this by constraining the agent to documented WinUI 3 patterns and giving it tools that verify actual build and run outcomes. The README describes the result as the agent having ground-truth answers instead of guesses when tools like winapp and dotnet are available to confirm state.

The comparison point within the WinUI 3 ecosystem itself is using Visual Studio with the Windows App SDK extension, which provides templates and IntelliSense but no AI-driven scaffolding or end-to-end packaging workflow. win-dev-skills targets the users who already prefer working from a CLI agent session rather than a GUI IDE.

Maintenance, Licensing, and Repository Status

The repository is maintained by Microsoft under an MIT license. The last push was on 2026-09-25, which is recent. There are no GitHub releases at the time of the last push, consistent with the v0.x preview status: the README directs users to release tags for stable pins.

The repository includes CODE_OF_CONDUCT.md, CONTRIBUTING.md, SECURITY.md, and SUPPORT.md, which are standard for a Microsoft open-source repository. The THIRD_PARTY_NOTICES.md covers the licenses of any dependencies bundled with the plugin.

The MIT license permits use, modification, and redistribution. The preview status is an engineering commitment about stability, not a licensing restriction.

Editorial conclusion

win-dev-skills is the correct plugin for Windows developers who use GitHub Copilot CLI, Claude Code, or OpenAI Codex and want agent assistance that stays in the WinUI 3 lane rather than drifting to UWP or WPF. The preview warning is real: v0.x carries no SemVer commitment, skill names and configuration can change without notice, and the README explicitly states that outputs are suggestions to review before committing or shipping. Verify you are on Windows App SDK 2.1.3 or later before starting: older versions had a XAML compiler bug that produced cryptic build failures. The last push was on 2026-09-25.

Frequently asked questions

Official sources

1. Issues
2. License: MIT
3. microsoft/win-dev-skills on GitHub
4. README