The skill is based on Expo SDK (docs from expo/expo repo), generated at 2026-02-26.
Expo provides tooling and services for React Native: app config and Prebuild (Continuous Native Generation), Expo SDK packages, development builds, EAS Build (cloud builds and internal distribution), and EAS Update (over-the-air JS updates). Use development builds for production apps; Expo Go is a limited playground.
Core References
| Topic | Description | Reference |
|---|
| App config | app.json, app.config.js/ts, dynamic config, reading in app | core-config |
| Development workflow | Dev loop, development builds vs Expo Go, when to rebuild | core-development-workflow |
| Development and production modes | DEV, --no-dev --minify, when to use each | core-development-mode |
| Metro | metro.config.js, resolver, transformer, cache, env vars | core-metro |
| Logging | Console in terminal, native logs, log-android / log-ios | core-logging |
| CNG and Prebuild | npx expo prebuild, --clean, EAS Build and native dirs | core-continuous-native-generation |
Features
Expo SDK and native code
| Topic | Description | Reference |
|---|
| Expo SDK and third-party libs | Install with npx expo install, compatibility, config plugins | features-expo-modules |
| expo-constants | App manifest, build info, system constants, extra/env at runtime | features-sdk-constants |
| expo-image | Performant image component, caching, BlurHash/ThumbHash, contentFit | features-sdk-image |
| expo-file-system | File and directory API, Paths.cache/document, read/write, download | features-sdk-filesystem |
| expo-secure-store | Encrypted key-value store, optional biometric auth | features-sdk-secure-store |
| Config plugins | Use and write plugins to modify AndroidManifest, Info.plist during prebuild | features-config-plugins |
| Native modules | Expo Modules API, local module, config plugin for native config, lifecycle | features-native-modules |
EAS Build and Submit
| Topic | Description | Reference |
|---|
| EAS Build | Cloud builds, eas.json profiles, development/preview/production | features-eas |
| EAS Submit | Submit to Google Play and App Store (TestFlight), eas.json, CI | features-eas-submit |
Development experience
| Topic | Description | Reference |
|---|
| iOS Simulator and Android emulator | Setup, npx expo start + i/a, limitations, troubleshooting | features-simulators-emulators |
Updates and versioning
| Topic | Description | Reference |
|---|
| expo-updates and EAS Update | OTA updates, runtime version, channels | features-updates |
| Upgrading Expo SDK | Incremental upgrade, npx expo install --fix, expo-doctor | features-versioning |
Best practices