winapp-maui

A packaging guide for .NET MAUI Windows apps, which are cross-platform .NET apps that can run on Windows. It explains how to create and sign MSIX packages or unpackaged builds with winapp.

In plain words
What is it for?
Use it when packaging or signing a MAUI Windows app, setting up CI builds, or fixing unresolved placeholder errors from winapp.
Why use it?
It helps avoid packaging failures caused by using the source manifest before MAUI has replaced its placeholder values with generated ones.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/microsoft/winappcli/winapp-maui
Any agent
npx skills add microsoft/winappCli --skill winapp-maui
Clone the repo
git clone --depth 1 https://github.com/microsoft/winappCli

Made for: Claude Code, Codex.

Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,117 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00071 $0.03117
Opus 5 $0.00036 $0.01558
Sonnet 5 $0.00014 $0.00623
Haiku 4.5 $0.00007 $0.00312

Measured 3d ago against content hash bc73941539cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

winapp-maui scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/winapp/skills/winapp-maui/SKILL.md · 213 lines

How it starts

The opening of the file, as written. The whole thing — 213 lines — stays where its author put it; the contents beside it link to each section on GitHub.

When to use

Use this skill when:

  • Packaging or signing a .NET MAUI Windows app with winapp (winapp package / winapp sign)
  • winapp package fails with an error like "manifest contains unresolved placeholders: $placeholder$"
  • Deciding which manifest to hand to winapp for a MAUI Windows head project
  • Setting up CI/CD (GitHub Actions) that builds a MAUI app and produces a signed MSIX and/or signed unpackaged build

MAUI is not a "run winapp init" framework — the Windows head already has a manifest and a build system that generates the real one for you. The only trick is pointing winapp at the generated manifest, never the source one.

The resizetizer dependency (root cause)

A .NET MAUI project has a source manifest at Platforms/Windows/Package.appxmanifest with placeholder tokens that the MAUI build pipeline resolves:

<Identity Name="maui-package-name-placeholder" Publisher="CN=User Name" Version="0.0.0.0" />
<Properties>
  <DisplayName>$placeholder$</DisplayName>
  <PublisherDisplayName>User Name</PublisherDisplayName>
  <Logo>$placeholder$.png</Logo>
</Properties>
...
<uap:VisualElements DisplayName="$placeholder$" ... Square150x150Logo="$placeholder$.png" Square44x44Logo="$placeholder$.png">

These are resolved at build/publish time by Microsoft.Maui.Resizetizer (bundled with the MAUI workload), which reads MSBuild properties (ApplicationTitle, ApplicationId, ApplicationDisplayVersion, the MauiIcon/MauiSplashScreen items, etc.), generates the app icon/tile/splash assets, and writes a resolved manifest into the intermediate output.

Why winapp trips on this: winapp package only auto-resolves its own entry-point tokens — $targetnametoken$ and $targetentrypoint$ (via --executable). It does not understand MAUI's $placeholder$ tokens. If you point winapp at the raw Platforms/Windows/Package.appxmanifest, packaging fails because those placeholders are still literal $placeholder$ strings.

Read the full file on GitHub · 213 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 213 lines · 71 tokens per session scan A bc73941539cd

Subscribe to this mod's changes

winapp-maui is a skill published in the GitHub repository microsoft/winappCli (1,205 stars, last pushed 4d ago), licensed MIT. It adds 71 tokens to every session and 3,117 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.