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Agent skill

Mobile App Developer

by happycapy-ai in happycapy-ai/Happycapy-skills

End-to-end mobile app development and publishing using Expo + EAS.

MITAuto-check passedMobile

Install Mobile App Developer

skills CLI
$ npx skills add happycapy-ai/Happycapy-skills --skill mobile-app-developer -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install happycapy-ai/Happycapy-skills mobile-app-developer --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/happycapy-ai/Happycapy-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/mobile-app-developer .claude/skills/mobile-app-developer && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
mobile-app-developer
GitHub stars
137
Token cost
~1.3k tokens
SKILL.md length
530 words
Files
4
Skills in repo
28
Repo updated
First seen
Licence
MIT

At a glance

End-to-end mobile app development and publishing using Expo + EAS.

  • The user wants to build
  • SKILL.md covers When to Trigger, Skill Layout, Default Tech Stack and Hard Preconditions, plus 4 more sections
  • Calls node, npm and curl; reaches expo.dev and docs.expo.dev; needs EXPO_TOKEN
  • Automate the release pipeline of a React Native / Expo iOS

What it does

Mobile App Developer is an agent skill from happycapy-ai/Happycapy-skills. End-to-end mobile app development and publishing using Expo + EAS. Covers project scaffolding, asset preparation, peer-dep / lock-file troubleshooting (development.md), web preview with phone frame and Expo Go QR code (preview.md), AND automated build + submit to TestFlight / App Store (publishing.md), with full automation via Apple ASC API Key (no Mac, no Xcode, no 2FA required). Use when the user wants to build, test, preview, publish, or automate the release pipeline of a React Native / Expo iOS or Android app.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. The skill folder holds 3 other files (for example `development.md`, `preview.md` and `publishing.md`).

It sits in Mobile, covering Cross-platform mobile apps, App store release and Project scaffolding. It works with Expo, App Store Connect, React Native and iOS. The repository describes itself as: A curated collection of high-quality Claude Code skills to enhance your development workflow. The licence is MIT.

When your agent uses it

  • The user wants to build
  • Automate the release pipeline of a React Native / Expo iOS

Example prompts

  • “/mobile-app-developer”

Requirements

  • A credential in EXPO_TOKEN

What it can do on your machine

Read from SKILL.md and the folder at commit 9ff72fe. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • node
    • npm
    • curl
    • apt-get
    • expo

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • expo.dev
    • docs.expo.dev

    Also links to:

    • appstoreconnect.apple.com
    • play.google.com

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names these keys or tokens, usually read from environment variables:

    • EXPO_TOKEN

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Mobile App Developer loads about 1.3k tokens when it runs. Until then it costs about 135 tokens; SKILL.md has 530 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~135
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from happycapy-ai/Happycapy-skills at commit 9ff72fe, republished under its MIT licence (© happycapy-ai). 530 words, ~1,285 tokens.

Download SKILL.mdSave it as .claude/skills/mobile-app-developer/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.
name
mobile-app-developer
description
End-to-end mobile app development and publishing using Expo + EAS. Covers project scaffolding, asset preparation, peer-dep / lock-file troubleshooting (development.md), web preview with phone frame and Expo Go QR code (preview.md), AND automated build + submit to TestFlight / App Store (publishing.md), with full automation via Apple ASC API Key (no Mac, no Xcode, no 2FA required). Use when the user wants to build, test, preview, publish, or automate the release pipeline of a React Native / Expo iOS or Android app.

mobile-app-developer

End-to-end playbook for shipping an Expo / React Native app — from scaffolding to TestFlight / Play Store — fully automated from a Linux sandbox.

When to Trigger

Trigger this skill when the user wants to:

  • Scaffold or modify a React Native / Expo project
  • Run / test / debug the app locally (Expo Go, dev client, simulator)
  • Generate a web preview page with phone frame + Expo Go QR code
  • Configure EAS Build (cloud build) for iOS or Android
  • Publish to TestFlight (iOS internal testing) or Google Play Internal Testing
  • Submit to App Store / Play Store public release
  • Set up ASC API Key auth (bypass Apple 2FA)
  • Replace icons / splash screens for store compliance
  • Diagnose EAS build failures (peer deps, lock files, credentials, fingerprint, etc.)

Do NOT trigger for: pure native iOS/Android (no Expo), Flutter, Cordova/Capacitor, KMP/Compose Multiplatform.

Skill Layout

This skill is split into focused documents. Read the relevant one(s) on demand — do NOT preload all.

FileRead when…
development.mdSetting up project, installing deps, configuring app.json, preparing icons/splash, running on simulator/device, fixing peer-dep / lock-file errors, managing env vars / secrets
publishing.mdConfiguring eas.json submit profile, ASC API Key / Play Service Account, running build + submit, diagnosing submit failures, App Store / Play Store metadata checklists
preview.mdGenerating a web preview page with phone frame + Expo Go QR code. Uses Expo Web (react-native-web) static export for browser preview and Expo dev server for real-device QR scanning

If the user's task spans multiple (e.g. "build a new Expo app and ship it to TestFlight"), read development.md first, then publishing.md.

Default Tech Stack

LayerChoice
FrameworkExpo (latest stable — check https://docs.expo.dev/versions/latest/ before scaffolding)
Build / DistributionEAS Build + EAS Submit (Expo cloud)
Auth (Apple)App Store Connect API Key (.p8) — bypasses 2FA
Auth (Google)Play Console Service Account JSON
Auth (Expo)Personal Access Token via EXPO_TOKEN
Show full SKILL.md (235 more words)Show less

Hard Preconditions

Before starting any build or publish work, confirm with the user:

  • Expo account + EXPO_TOKEN (https://expo.dev/accounts/<user>/settings/access-tokens)
  • For iOS:
    • Apple Developer account (paid, $99/year)
    • ASC API Key: .p8 file + Issuer ID + Key ID (role ≥ App Manager; ≥ Admin to create certs)
    • Apple Team ID + ASC App ID + Bundle Identifier
  • For Android:
    • Google Play Console account ($25 one-time)
    • Service Account JSON key (created in Play Console → API access)
    • Package name + Play Console app already created
    • First AAB must be uploaded manually to Play Console before automation works

If anything is missing, ask the user before proceeding. Do not guess.

Sandbox Requirements

The sandbox/CI must have:

bash
node --version       # >= 18
npm --version        # >= 9
convert -version     # ImageMagick — for icon/splash conversion
expect -v            # for first-time non-interactive credential setup
curl --version       # for fetching build logs

Quick check:

bash
for cmd in node npm convert expect curl; do
  command -v $cmd >/dev/null 2>&1 && echo "[OK] $cmd" || echo "[MISSING] $cmd"
done

If anything is missing, install before continuing (apt-get install imagemagick expect).

Architecture Recommendation

PhaseAI/API key locationWhy
Internal testing (TestFlight / Play Internal)OK to call AI Gateway directly from clientSpeed of iteration; risk is bounded by closed tester pool
Public releaseMUST proxy through your own backendEmbedded keys can be extracted from any IPA/AAB

Useful URLs

Notes

  • All commands tested on Linux. macOS users get extra options (local Xcode, simctl) which this skill avoids for portability.
  • Treat .p8 files and Service Account JSONs like passwords. Always gitignore (*.p8, *-service-account.json).
  • This skill assumes EAS cloud build. Local builds (expo prebuild + native toolchain) are out of scope.

© happycapy-ai, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files in skills/mobile-app-developer of happycapy-ai/Happycapy-skills.

  • SKILL.md
  • development.md
  • preview.md
  • publishing.md

Open the folder on GitHubat commit 9ff72fe

Compare with similar skills

Mobile App Developer next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Mobile App Developer compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Mobile App Developer this skillhappycapy-ai/Happycapy-skills137—~1.3kAutomated safety check: PassMIT
Eas App Storesexpo/skills2.7k—~1.9kAutomated safety check: PassMIT
Expo Deploymentkingstinct/react-native-healthkit7164 repos~930Automated safety check: PassMIT
Local BuildCode-with-Beto/skills141—~2kAutomated safety check: PassNone
Iapkit E2E Martiehyodotdev/openiap154—~5.4kAutomated safety check: NotesMIT
Iapkit E2E Petguhyodotdev/openiap154—~1.1kAutomated safety check: PassMIT

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Works with

Categories

Questions about Mobile App Developer

What does Mobile App Developer do?

End-to-end mobile app development and publishing using Expo + EAS. Mobile App Developer is an agent skill from happycapy-ai/Happycapy-skills. End-to-end mobile app development and publishing using Expo + EAS.

When should I use Mobile App Developer?

Mobile App Developer fits situations like: the user wants to build; automate the release pipeline of a React Native / Expo iOS.

How do I install Mobile App Developer in Claude Code?

Run `npx skills add happycapy-ai/Happycapy-skills --skill mobile-app-developer -a claude-code`. Or copy the skill folder (skills/mobile-app-developer in happycapy-ai/Happycapy-skills) into .claude/skills/mobile-app-developer in your project. Claude Code loads it when a task matches its description.

How do I install Mobile App Developer in Codex?

Run `npx skills add happycapy-ai/Happycapy-skills --skill mobile-app-developer -a codex`. Or copy the skill folder (skills/mobile-app-developer in happycapy-ai/Happycapy-skills) into .agents/skills/mobile-app-developer in your project. Codex loads it when a task matches its description.

Can I use Mobile App Developer in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add happycapy-ai/Happycapy-skills --skill mobile-app-developer -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/mobile-app-developer, .gemini/skills/mobile-app-developer, .github/skills/mobile-app-developer and .opencode/skills/mobile-app-developer in your project.

What does Mobile App Developer need to run?

Going by SKILL.md and its folder, Mobile App Developer needs the command-line tools its instructions call (node, npm, curl, apt-get and expo) and credentials named EXPO_TOKEN. Our summary lists: A credential in EXPO_TOKEN.

Does Mobile App Developer access the network?

SKILL.md names 4 domains. In commands or code: expo.dev and docs.expo.dev; the agent is likely to contact these when it follows the instructions. As links in the text: appstoreconnect.apple.com and play.google.com. This is read from the text; nothing was executed.

Is Mobile App Developer safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Mobile App Developer use?

Mobile App Developer is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Mobile App Developer use?

About 1.3k tokens (SKILL.md is roughly 5.1k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Mobile App Developer?

Skills that share tags, products or a category with Mobile App Developer: Eas App Stores (expo/skills, 2.7k stars), Expo Deployment (kingstinct/react-native-healthkit, 716 stars), Local Build (Code-with-Beto/skills, 141 stars) and Iapkit E2E Martie (hyodotdev/openiap, 154 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Mobile App Developer?

happycapy-ai (a GitHub user) maintains it in happycapy-ai/Happycapy-skills, which has 137 GitHub stars. The repository holds 28 skills in this directory. The repository was last updated on September 3, 2026.

Source: happycapy-ai/Happycapy-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.