Expo Development

Master skill for building, styling, deploying, and upgrading Expo / React Native applications with EAS (Expo Application Services).

When to Use This Skill vs. Alternatives

Expo (this skill) -- Default choice for mobile apps. Use when: targeting iOS + Android (+ web), want managed native builds, prefer file-based routing, need OTA updates.
React Native CLI -- Only when: brownfield integration into existing native app, need full Xcode/Gradle control, corporate policy forbids third-party build services.
Flutter / other -- Out of scope. If user asks, note Expo covers the React Native ecosystem.

Decision Tree -- Pick the Right Reference

Read the user's task, then follow this tree:

Styling with Tailwind / NativeWind / CSS? --> ./references/tailwind-setup.md (Tailwind v4 + NativeWind v5 + react-native-css wrappers)
Creating server endpoints or backend logic? --> ./references/api-routes.md (+api.ts files, EAS Hosting on Cloudflare Workers)
CI/CD, build automation, workflow YAML? --> ./references/cicd.md (EAS Workflows syntax, pre-packaged jobs, validation scripts)
Custom dev client / native module testing? --> ./references/dev-client.md (when Expo Go is insufficient -- native modules, widgets, extensions)
Deploying or publishing to stores / web? --> ./references/deployment.md (orchestrates the sub-references below)
- TestFlight beta testing --> ./references/testflight.md
- iOS App Store submission --> ./references/ios-app-store.md
- Google Play Store --> ./references/play-store.md
- App Store metadata & ASO --> ./references/app-store-metadata.md
- Workflow-based deploys --> ./references/workflows.md
Upgrading Expo SDK or fixing breaking changes? --> ./references/upgrading.md (orchestrates the sub-references below)
- New Architecture migration --> ./references/new-architecture.md
- React 19 changes --> ./references/react-19.md
- React Compiler setup --> ./references/react-compiler.md
- Native Tabs (SDK 55) --> ./references/native-tabs.md
- expo-av to expo-audio --> ./references/expo-av-to-audio.md
- expo-av to expo-video --> ./references/expo-av-to-video.md
Performance, profiling, Hermes, New Architecture perf, 60 FPS, Reanimated? --> ./references/performance-profiling.md (JSI, TurboModules, Fabric, React Compiler, FlatList, memory)
App version management, buildNumber, versionCode, autoIncrement, appVersionSource? --> ./references/eas-version-management.md (remote vs local source, CI/CD versioning, semantic versioning)
OTA updates, EAS Update, update channels, rollback, staged rollout, canary? --> ./references/eas-update-strategy.md (channels, branches, monitoring, critical updates, workflows)
Streaming responses, expo/fetch, SSE, AI chat streaming, WinterCG? --> ./references/expo-fetch-streaming.md (ReadableStream, Claude/OpenAI streaming, SSE parsing, abort)
Multiple domains? Load all relevant references. They are designed to be composed.

CI/CD Scripts

The CI/CD skill includes helper scripts for fetching EAS workflow schemas and validating workflow YAML files:

# Fetch EAS workflow reference docs (caches with ETags)
node {baseDir}/scripts/fetch.js <url>

# Validate workflow YAML against schema
[ -d "{baseDir}/scripts/node_modules" ] || npm install --prefix {baseDir}/scripts
node {baseDir}/scripts/validate.js <workflow.yml>

Key URLs for CI/CD reference:

Schema: https://api.expo.dev/v2/workflows/schema
Syntax docs: https://raw.githubusercontent.com/expo/expo/refs/heads/main/docs/pages/eas/workflows/syntax.mdx
Pre-packaged jobs: https://raw.githubusercontent.com/expo/expo/refs/heads/main/docs/pages/eas/workflows/pre-packaged-jobs.mdx

Quick Commands

# Start development
npx expo start                    # Expo Go
npx expo start --dev-client       # Custom dev client

# Build
npx eas-cli@latest build -p ios --profile production
npx eas-cli@latest build -p android --profile production

# OTA Update
npx eas-cli@latest update --channel production --message "Fix"

# Version management
npx eas-cli@latest build:version:get
npx eas-cli@latest build:version:set --platform ios

# Deploy
npx testflight                    # Quick TestFlight submission
npx eas-cli@latest deploy --prod  # Web / API route deployment

# Upgrade SDK
npx expo install expo@latest && npx expo install --fix
npx expo-doctor                   # Diagnostics

# API routes
npx expo serve                    # Local server with API routes
eas deploy                        # Deploy to EAS Hosting

Rules

ALWAYS use npx eas-cli@latest (not bare eas) to avoid stale CLI versions.
ALWAYS run npx expo-doctor after SDK upgrades or dependency changes.
Prefer Expo Go for development. Only build dev clients when native modules require it.
Use appVersionSource: "remote" in eas.json so EAS manages version numbers.
For Tailwind in React Native, wrap components with useCssElement -- direct className on RN primitives does not work.
When unsure about an Expo API, use Context7 (resolve-library-id -> query-docs) rather than guessing.
Use expo/fetch (not global fetch) for any streaming response or AI API integration in React Native.
OTA updates only work for JS/asset changes -- any native code change requires a new store build.

Cross-References

UI components for Expo: See building-native-ui skill for native UI patterns
DOM components in Expo: See use-dom skill for web-view based components in React Native
Tailwind styling details: See ./references/tailwind-setup.md for CSS wrappers and platform colors