WinUI 3 MSIX Packaging with the winui-packaging Skill

Where this fits

You've just finished the last feature of your WinUI 3 app. Now you need a signed MSIX installer, a trusted certificate for local testing, and a pipeline that can build the release artifact without you babysitting it. winui-packaging turns those manual Windows packaging chores into commands your agent can run, verify, and repeat.

Why agents benefit

• Generate a dev certificate and trust it in one sequence (winapp cert generate + winapp cert install), so the agent can bootstrap local signing environments.
• Build release binaries and package them into an MSIX without needing a human to click through Visual Studio's Publish wizard.
• Sign existing MSIX files or packages using a provided .pfx, enabling post-build signing in CI.
• Create self-contained deployments that bundle the .NET runtime, which simplifies target-machine prerequisites.
• Drive the full release flow in scripts — build, generate/trust certs, package, sign, and upload artifacts to GitHub Actions or prepare for Store submission.

Practical scenarios

Local release build with a signed installer

A developer hands the agent a repo and asks for a release MSIX. The agent runs BuildAndRun.ps1 -c Release --arch x64 --no-launch, generates a dev certificate with winapp cert generate, then packages and signs with winapp package <dir> --generate-cert --install-cert. Result: a ready-to-install MSIX without opening a single dialog.

CI/CD packaging in GitHub Actions

Your team wants every tagged commit to produce a signed, self-contained installer. The agent can add the skill commands to a workflow: build for release, winapp package <dir> --cert devcert.pfx --self-contained, then upload the MSIX as an artifact. This gives consistent artifacts without maintaining separate packaging scripts.

Preparing for Microsoft Store submission

Before uploading, you need to verify that app identity, capabilities, and signing align with Store requirements. The agent uses the same packaging workflow to generate the Store-ready MSIX, checks that the certificate matches the Publisher entry, and leaves you with an .appxupload candidate for Partner Center.

Add it to your agent workflow

Install the skill with:

npx skills add microsoft/win-dev-skills --skill winui-packaging

Then, for example, ask your agent: "Package the app in Release for x64 and sign it." The agent will execute the equivalent of:

.\BuildAndRun.ps1 . -c Release --arch x64 --no-launch
winapp package . --cert devcert.pfx

For a first-time local setup, the agent can generate and trust a certificate automatically with winapp package <dir> --generate-cert --install-cert.

Compare before adopting

Evaluate winui-packaging against manually invoking MakeAppx.exe, SignTool, and New-SelfSignedCertificate, or against other Windows packaging skills. Look at repo freshness (the Microsoft dev skills repo is actively maintained), the clarity of the quick-reference commands, and whether the skill fits your existing CI and Store pipeline. If you only need one-off MSIX creation, a simpler script may be enough; if you want an agent that can reason about the whole release process, this skill is worth the dependency.

Why it is worth tracking

Microsoft is the author, and the repo has 407 stars, which is a solid signal for a specialized helper skill. More importantly, this skill represents a shift toward letting agents handle release engineering for Windows apps. If your team ships WinUI 3 apps, evaluate it as soon as you feel the pain of manual signing and packaging. For more context, see the skill detail page at https://www.openagentskill.com/skills/microsoft-winui-packaging.