Production Mobile Android Setup (Expo + React Native)

MultiModel Dev OS v1.2.0 adds a dedicated production-ready template for mobile Android clients under [examples/expo-react-native-android/](file:///F:/multimodel-dev-os/examples/expo-react-native-android/).

This guide describes how to customize and deploy this template using Expo EAS Build pipelines.

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1. Directory Structure

The expo-react-native-android template structures standard mobile files:

• app.json: Global metadata mapping package namespaces (com.multimodel.devos), app icons, orientation constraints, and runtime permissions.
• eas.json: Configuration profile mapping for Expo EAS Build pipelines.
• app.config.ts: TypeScript config dynamically mapping environment profiles.
• src/services/api-client.ts: Standardized fetch client with connection timeout limits.
• src/lib/secure-storage.ts: Storage wrapper interface utilizing expo-secure-store.
• src/app/_layout.tsx: Expo Router root Layout component displaying loading/offline network states.
• jest.config.js: Jest configuration setting up native Expo mocks and test suites.

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2. Environment Configurations

EAS Build uses the APP_ENV environment variable to direct endpoint paths:

Profile / APP_ENV	Target API BaseUrl	Distribution Method
development	http://10.0.2.2:3000/api	Expo Go Dev Client
staging	https://staging-api.multimodel.dev	Internal testing APK
production	https://api.multimodel.dev	Play Store AAB Bundle

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3. Build & Submission Command Lines

To trigger builds on EAS servers:

# Build development client APK
eas build --profile development --platform android

# Build staging preview APK
eas build --profile preview --platform android

# Build production bundle AAB
eas build --profile production --platform android

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4. Mobile Quality Assurance (QA) Checklist

To verify app compliance before distribution:

1. No committed secrets: Do not write keys inside app.config.ts or app.json. Use EAS secrets vault.
2. Offline Handlers: Verify layout redirects properly to connection failure views when network states drop.
3. Session Encryptions: Confirm tokens are stored exclusively inside secure-storage.ts (expo-secure-store), not AsyncStorage.

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5. Android & Expo Template FAQ

Q: Why does the API call fail in the Android Emulator when using localhost?

In Android emulators, localhost or 127.0.0.1 refers to the emulator's loopback interface itself, not your host computer. The host computer's loopback interface is mapped to the special IP address 10.0.2.2. The api-client automatically resolves this default when APP_ENV is set to development.

Q: How do I handle EAS credentials errors during eas build?

EAS credentials errors usually occur when the projectId or owner in app.config.ts does not match your Expo Developer account. To resolve this:

1. Log in to your Expo account via command line: npx eas login.
2. Configure your own Expo username in app.config.ts under owner.
3. Generate a project ID on your Expo dashboard and update the projectId placeholder in app.config.ts.

Q: How do I test the API client's retry mechanism locally?

You can toggle offline mock responses by setting useMockData: true inside [api-client.ts](file:///f:/multimodel-dev-os/examples/expo-react-native-android/src/services/api-client.ts) constructor, or you can temporarily disconnect your development server to watch the console log warning attempts: [ApiClient] Attempt 1 failed: fetch failed. Retrying... The client will automatically retry up to 3 times before returning a Max retries exceeded error.