Builds, optimizes, and debugs cross-platform mobile applications with React Native and Expo. Implements navigation hierarchies (tabs, stacks, drawers), configures native modules, optimizes FlatList rendering with memo and useCallback, and handles platform-specific code for iOS and Android. Use when building a React Native or Expo mobile app, setting up navigation, integrating native modules, improving scroll performance, handling SafeArea or keyboard input, or configuring Expo SDK projects.
Builds, optimizes, and debugs cross-platform mobile applications with React Native and Expo. Implements navigation hierarchies (tabs, stacks, drawers), configures native modules, optimizes FlatList rendering with memo and useCallback, and handles platform-specific code for iOS and Android. Use when building a React Native or Expo mobile app, setting up navigation, integrating native modules, improving scroll performance, handling SafeArea or keyboard input, or configuring Expo SDK projects.
Senior mobile engineer building production-ready cross-platform applications with React Native and Expo.
Core Workflow
Setup — Expo Router or React Navigation, TypeScript config → run npx expo doctor to verify environment and SDK compatibility; fix any reported issues before proceeding
Structure — Feature-based organization
Implement — Components with platform handling → verify on iOS simulator and Android emulator; check Metro bundler output for errors before moving on
Optimize — FlatList, images, memory →
profile with Flipper or React DevTools
Test — Both platforms, real devices
Error Recovery
Metro bundler errors → clear cache with npx expo start --clear, then restart
iOS build fails → check Xcode logs → resolve native dependency or provisioning issue → rebuild with npx expo run:ios
Android build fails → check adb logcat or Gradle output → resolve SDK/NDK version mismatch → rebuild with npx expo run:android
Native module not found → run npx expo install <module> to ensure compatible version, then rebuild native layers
Reference Guide
Load detailed guidance based on context:
Topic
Reference
Load When
Navigation
references/expo-router.md
Expo Router, tabs, stacks, deep linking
Platform
references/platform-handling.md
iOS/Android code, SafeArea, keyboard
Lists
references/list-optimization.md
FlatList, performance, memo
Storage
references/storage-hooks.md
AsyncStorage, MMKV, persistence
Structure
references/project-structure.md
Project setup, architecture
Constraints
MUST DO
Use FlatList/SectionList for lists (not ScrollView)
Implement memo + useCallback for list items
Handle SafeAreaView for notches
Test on both iOS and Android real devices
Use KeyboardAvoidingView for forms
Handle Android back button in navigation
MUST NOT DO
Use ScrollView for large lists
Use inline styles extensively (creates new objects)
Hardcode dimensions (use Dimensions API or flex)
Ignore memory leaks from subscriptions
Skip platform-specific testing
Use waitFor/setTimeout for animations (use Reanimated)