mobile-developer

The saved excerpt is a snapshot from review. The external source remains the complete and most current version.

---
name: mobile-developer
description: Expert mobile developer for React Native, native Swift/SwiftUI, Kotlin/Compose, and mobile CI/CD (Fastlane, Codemagic, Bitrise, EAS). Use for everything mobile that flutter-mobile does NOT cover. For Flutter 3.41.x work, use flutter-mobile skill instead.
allowed-tools: Bash, Read, Write, Edit, Glob, Grep
metadata:
  triggers: React Native, React Native New Architecture, Hermes, TurboModules, SwiftUI, Kotlin Compose, Fastlane, Codemagic, Bitrise, EAS Update, CodePush, Detox, native module, brownfield, Expo, MAUI
  related-skills: flutter-mobile, mobile-design
  domain: frontend
  role: specialist
  scope: implementation
  output-format: code
last-reviewed: "2026-03-15"
---

## Iron Law

**FOR FLUTTER WORK — USE `flutter-mobile` SKILL INSTEAD. This skill is for React Native, native Swift/Kotlin, and mobile CI/CD only.**

# Mobile Developer Skill

## Disambiguation — Which Skill to Use

| Task | Use This Skill | Use flutter-mobile Instead |
|------|---------------|---------------------------|
| React Native app | YES | No |
| Flutter screen/provider/widget | No | YES |
| Native Swift/SwiftUI module | YES | No |
| Native Kotlin/Compose module | YES | No |
| Fastlane lanes / Codemagic pipeline | YES | No |
| EAS Update / CodePush OTA | YES | No |
| Flutter CI/CD (GitHub Actions, build) | No — use deployment-engineer agent | No |
| Detox E2E (React Native) | YES | No |
| Maestro E2E (Flutter) | No | YES (via flutter-mobile) |
| App Store signing (any) | No | No — use asc-signing-setup skill |

## Capabilities

### 1. React Native (RN 0.74+, New Architecture)
New Architecture (Fabric renderer, TurboModules, JSI), Hermes engine, Metro bundler configuration, Flipper debugging, Codegen for typed native modules, and the bridge-free JSI layer for synchronous native calls.

### 2. Expo (SDK 50+)
EAS Build for managed and bare workflows, EAS Update for over-the-air JS bundle delivery, development builds with custom native code, config plugins for extending native projects without ejecting.

### 3. Native Integration
Swift/SwiftUI platform channel implementations (method channels, event channels), Kotlin/Compose native module authoring, brownfield integration (embedding RN screens in an existing native app or vice versa).

### 4. Architecture
Clean Architecture for React Native (data/domain/presentation layers), MVVM with React Query or Zustand, MVI with Redux Toolkit, BLoC pattern adapted for RN, feature-first folder structure mirroring the flutter-mobile convention.

### 5. Performance
App startup time reduction (Hermes bytecode, lazy loading), memory leak detection (Flipper Memory Monitor, Instruments, Android Profiler), battery impact analysis, FlatList/FlashList virtualization, Reanimated 3 for 60fps UI-thread animations, InteractionManager for deferred heavy work.

### 6. Data Management
Realm for complex relational offline data, WatermelonDB for high-performance sync, MMKV for fast key-value storage, offline-first sync patterns with conflict resolution (last-write-wins, CRDT), background sync with WorkManager (Android) and BGTaskScheduler (iOS).

### 7. Mobile CI/CD
Fastlane lanes (match for code signing, gym for builds, pilot/deliver for distribution), Codemagic YAML workflows, Bitrise pipelines, GitHub Actions with mobile-specific caching (CocoaPods, Gradle), CodePush for hotfix OTA, EAS Update for Expo-managed OTA.

### 8. Testing
Jest unit tests with `@testing-library/react-native`, Detox for black-box E2E on device/emulator, Maestro for declarative E2E (RN and native), XCTest for Swift unit tests, Firebase Test Lab and Bitrise device farm for multi-device coverage.

### 9. Security
OWASP MASVS compliance (MASVS-STORAGE, MASVS-CRYPTO, MASVS-NETWORK, MASVS-AUTH), `react-native-keychain` / `expo-secure-store` for credential storage, certificate pinning via `react-native-ssl-pinning` or TrustKit (iOS), RASP (Runtime Application Self-Protection), jailbreak/root detection.

## Quick Reference — R