expo

name	expo
description	Expo framework for universal React Native apps — routing, SDK modules, EAS builds, OTA updates, and config plugins
layer	domain
category	mobile
triggers	["expo","expo router","eas build","eas update","expo config plugin","expo go","app.config.ts","expo modules"]
inputs	[{"requirements":"Target platforms (iOS, Android, Web), features, SDK modules needed"},{"workflow":"Expo Go | Development build | EAS Build"}]
outputs	[{"project_config":"app.config.ts and EAS configuration"},{"routing":"File-based navigation with Expo Router"},{"native_modules":"SDK module integration and config plugins"}]
linksTo	["react-native","react","typescript-frontend","vercel"]
linkedFrom	["react-native","cook","plan"]
riskLevel	low

Expo

Framework and platform for building universal React Native applications targeting iOS, Android, and web from a single codebase with managed native tooling.

When to Use

• Building a new mobile or universal app with React Native
• Need file-based routing (Expo Router)
• Want managed native builds without Xcode/Android Studio (EAS Build)
• Need OTA updates without app store resubmission
• Integrating native device APIs (Camera, FileSystem, Notifications, etc.)
• Creating custom native modules with the Expo Modules API

Key Patterns

• Expo Router: File-based routing in app/ directory — layouts, groups, dynamic routes, typed routes
• Expo SDK Modules: Curated native APIs — Camera, FileSystem, Notifications, SecureStore, Haptics, Location
• EAS Build: Cloud-native iOS/Android builds; eas build --platform all
• EAS Submit: Automated App Store and Google Play submission; eas submit
• Config Plugins: Modify native projects declaratively via app.config.ts plugins array
• Development Builds vs Expo Go: Dev builds include custom native code; Expo Go for SDK-only prototyping
• EAS Update: OTA JS/asset updates without store review; branch-based deployment channels
• Expo Modules API: Write custom native modules in Swift/Kotlin with typed bridge
• app.config.ts: Dynamic configuration with environment variables, build profiles, and plugin composition
• Universal Apps: Single codebase for iOS, Android, and web with platform-specific overrides via .ios.tsx/.android.tsx/.web.tsx

Anti-Patterns

Anti-Pattern	Why	Instead
Ejecting prematurely	Loses managed workflow benefits	Use config plugins or dev builds first
Using Expo Go for production testing	Missing custom native modules	Use development builds (npx expo run:ios)
Hardcoding env values in app.json	Leaks secrets, no per-environment config	Use with