Provides React Native performance optimization guidelines for FPS, TTI, bundle size, memory leaks, re-renders, and animations. Applies to tasks involving Hermes optimization, JS thread blocking, bridge overhead, FlashList, native modules, or debugging jank and frame drops.
Provides an incremental adoption strategy to migrate native iOS or Android apps to React Native or Expo using @callstack/react-native-brownfield for initial setup. Use when planning migration steps, packaging XCFramework/AAR artifacts, and integrating them into host apps.
Upgrades React Native apps to newer versions by applying rn-diff-purge template diffs, updating package.json dependencies, migrating native iOS and Android configuration, resolving CocoaPods and Gradle changes, and handling breaking API updates. Use when upgrading React Native, bumping RN version, updating from RN 0.x to 0.y, or migrating Expo SDK alongside a React Native upgrade.
Build native UI with the @expo/ui package: real SwiftUI on iOS and Jetpack Compose on Android rendered from React in an Expo or React Native app. Covers universal cross-platform components (Host, Column, Row, Button, Text, List, and more imported from @expo/ui), drop-in replacements for popular React Native community libraries (BottomSheet, DateTimePicker, Slider, Menu, etc.), and platform-specific SwiftUI (@expo/ui/swift-ui) and Jetpack Compose (@expo/ui/jetpack-compose) trees and modifiers. Use when adding or reviewing @expo/ui Host/RNHostView trees, building native-feeling UI where standard React Native components fall short (lists with swipe actions and sections, settings forms with toggles, menus, sheets, pickers, sliders), choosing between universal and platform-specific components, or replacing an RN community UI library with a native @expo/ui equivalent. Not for custom native modules, Expo Router navigation, Reanimated, or data fetching.
Use Expo DOM components to run web code in a webview on native and as-is on web. Migrate web code to native incrementally.