Mobile Development

The mobile cookbook holds five recipes for building iOS and Android apps with Claude Code, Codex, or Cursor: Expo, React Native, Flutter, native Swift and Kotlin, and cross-platform UI patterns. Each recipe pins the framework version, installs the vendor’s skills, and proves every change with type checks, tests, and simulator evidence instead of a diff read line by line.

This hub is for developers and tech leads who ship a mobile app with an agent. The agent reports “done”, the code compiles, and the screen still breaks on the Android emulator nobody opened. Pick a recipe and require the same evidence from every change.

Before you start, give the repository an agent instructions file; the prompts below write into it, and AGENTS.md and CLAUDE.md: concise repository context keeps it short. For recipes outside mobile, see the cookbook overview.

Which mobile recipe fits your stack?

Your app	Start with	What the recipe adds
New cross-platform app, or a team on Expo’s build and update services	Expo	Expo skills and MCP, Expo Router auth gates, a fingerprint-gated EAS pipeline, safe over-the-air (OTA) updates
React Native app that has outgrown the demo stage	React Native	Offline-first state, a janky list rebuilt on FlashList, biometric auth, CI to TestFlight and Play, failures the simulator never shows
Dart codebase, or a team that wants one rendering engine on both platforms	Flutter	Riverpod, go_router, Dio, clean architecture, widget tests
Swift/SwiftUI or Kotlin/Compose	Native iOS and Android	One build-and-test script per platform, simulator and emulator loops, UI-test evidence
Any of the above, and you need a screen built	React Native and Flutter UI recipes	12 prompts: adaptive navigation, feed lists, offline-first data, animations, push notifications, store submission

The Expo and React Native recipes are complementary: the Expo recipe covers the platform (routing, EAS builds, OTA updates), and the React Native recipe covers the app code that runs on it. On a new app, read the Expo recipe first.

Give the agent your stack’s official skills first

Install only your stack’s set, because skill descriptions compete for the agent’s attention. The claude, codex mcp and skills commands were checked on 2026-09-26 against claude 2.1.283, codex 0.157.1, and the skills CLI 1.7.0; the Codex Expo commands were rerun on 2026-10-02 with the same versions. Codex’s openai-curated marketplace also lists an Expo plugin, but on 2026-10-02 it shipped 13 skills under older names and no MCP server, so the Codex tab installs Expo’s current set and server directly. With --agent codex or --agent cursor, the skills CLI writes to .agents/skills/ in the project.

Claude Code

# Expo: 24 skills plus Expo's remote MCP server
# If the marketplace is missing: claude plugin marketplace add anthropics/claude-plugins-official
claude plugin install expo@claude-plugins-official

# Flutter and Dart: skills plus the Dart MCP server
claude plugin marketplace add flutter/agent-plugins
claude plugin install dart-flutter@dart-flutter

# React Native (Callstack, community) through the skills CLI
npx skills@latest add callstackincubator/agent-skills --skill '*' --agent claude-code -y

# iOS builds: MobileBuildMCP (needs macOS 14.5+ and Xcode 16+)
claude mcp add mobilebuild -- npx -y mobilebuildmcp@latest mcp

Codex

# Expo: the current skill set from expo/skills plus Expo's remote MCP server
npx skills@latest add expo/skills --skill '*' --agent codex -y
codex mcp add expo --url https://mcp.expo.dev/mcp
# If the server asks you to sign in: codex mcp login expo

# Flutter and React Native skills through the cross-agent skills CLI
npx skills@latest add flutter/agent-plugins --skill '*' --agent codex -y
npx skills@latest add callstackincubator/agent-skills --skill '*' --agent codex -y

# iOS builds: MobileBuildMCP (needs macOS 14.5+ and Xcode 16+)
codex mcp add mobilebuild -- npx -y mobilebuildmcp@latest mcp

Cursor

# Cursor installs skills through the cross-agent skills CLI
npx skills@latest add expo/skills --skill '*' --agent cursor -y
npx skills@latest add flutter/agent-plugins --skill '*' --agent cursor -y
npx skills@latest add callstackincubator/agent-skills --skill '*' --agent cursor -y

MCP servers, including MobileBuildMCP, go in .cursor/mcp.json; each recipe shows its entry.

Stack	Skill or server	Publisher	GitHub stars, 2026-09-26
Expo	expo/skills	Expo (official)	2,612
Flutter and Dart	flutter/agent-plugins (renamed from flutter/skills)	Flutter team (official)	2,996
React Native	callstackincubator/agent-skills	Callstack (community, not Meta)	1,656
iOS builds	MobileBuildMCP (npm mobilebuildmcp 2.7.1, formerly XcodeBuildMCP)	Sentry	about 6,400

Skill or MCP server? See the frontend skills roundup and the dev-server MCP servers.

How do you verify a mobile change without reading every line?

Make the agent produce evidence, and review the evidence. Every recipe uses the same four gates, in order:

1. Static gates. Run npx tsc --noEmit and your linter for React Native, or flutter analyze for Flutter. For Expo, add npx expo install --check to catch dependency versions the agent wrote by hand.
2. Unit and widget tests. Run flutter test, or your JavaScript test runner with React Native Testing Library. Write the acceptance criteria as tests before the agent writes the feature.
3. Both platforms, on a simulator or emulator. The agent launches the app on iOS and Android and attaches a screenshot of each changed screen (Maestro in the Expo recipe, XCUITest and Compose UI tests in the native one).
4. Release safety. A staged rollout in the store, and for Expo a fingerprint check so an OTA update never targets a build that lacks its native code.

The developer who opened the task signs off on the evidence; a tech lead owns the release gate. The evidence bundle carries it into a pull request, and mobile app testing patterns cover device matrices and flaky tests.

Copy-paste prompt: write the mobile verification contract

Inspect this repository and identify the mobile stack (Expo, bare React Native,
Flutter, or native), the framework version pinned in the lockfile, and the test
tools already installed. Then add a "Verify before done" section to AGENTS.md
(and CLAUDE.md if it exists) listing the exact commands for: type check, lint,
unit tests, and launching the app on one iOS simulator and one Android emulator.
Run every command once and report which pass, which fail, and which tools are
missing. Do not install anything or change app code.

Copy-paste prompt: ship one screen with evidence

Implement the change described in TASK.md. Before you write code, turn its
acceptance criteria into failing tests. When the tests pass, run the full
"Verify before done" list from AGENTS.md, then launch the app on the iOS
simulator and the Android emulator and save a screenshot of every changed
screen to evidence/. Finish with a summary: commands run with their results,
screenshot paths, and anything that differs between iOS and Android.
Do not run any EAS build, store submission, or OTA publish.

What breaks when agents build mobile apps?

• The agent pins versions from memory, writing APIs and config keys from an older SDK. Put the pinned version in AGENTS.md, and let npx expo install or flutter pub add choose package versions.
• “Done” without a device run. Reject any summary without a screenshot from each platform, and rerun the second prompt.
• One platform only. The agent tested whichever simulator was running; layout, permissions, and keyboard behaviour differ on the other. Name both targets in the prompt.
• Paid cloud builds run unattended. The eas-* skills drive paid Expo Application Services builds. Keep builds, submissions, and OTA publishes behind your approval.
• Too many tools in context. Each MCP server adds its tool list to every turn. Enable only what the task needs; the native recipe shows how to narrow MobileBuildMCP’s workflows.

Where to go next with mobile development

Expo Expo SDK 57: skills, MCP, Expo Router, EAS, and OTA updates

React Native Offline-first state, FlashList, biometrics, and store CI

Flutter Riverpod, go_router, Dio, and widget tests

Native iOS and Android SwiftUI and Compose with simulator loops and UI tests

React Native and Flutter UI recipes 12 copy-paste prompts for cross-platform mobile UI

Mobile app testing patterns Device matrices, platform-specific tests, and offline scenarios

Cursor users: see the Cursor mobile development guide. To supervise a long agent run from your phone, see driving agents from your phone.