React Native Brownfield Migration

Migrating to React Native

Use this skill only after the decision to adopt brownfield migration has been made. When the user is still choosing between brownfield, greenfield, a checkpoint-based path, defer, or no migration, use assess-react-native-migration first.

Overview

Prescriptive workflow for incremental adoption of React Native in existing native apps using @callstack/react-native-brownfield, from initial setup through phased host integration.

• Expo track

• Bare React Native track

Use one track per task unless the user explicitly asks for migration or comparison.

Migration Strategy

Use this strategy for brownfield migration planning and execution:

1. Assess app state and select Expo or bare path.

2. Perform initial setup with @callstack/react-native-brownfield.

3. Package RN artifacts (XCFramework/AAR) from the RN source app.

4. Integrate one RN surface into the host app and validate startup/runtime.

5. Repeat integration by feature/screen for incremental rollout.

Agent Guardrails (Global)

Apply these rules across all reference files:

1. Select one path first (Expo or bare) and do not mix steps.

2. Use placeholders from the docs (<framework_target_name>, <android_module_name>, <registered_module_name>) and resolve from project files.

3. Validate each packaging command before moving to host integration.

4. Run npx brownfield <command> --help before relying on any flag table in these references; help output wins.

5. Write stable project settings once into brownfield.config.* instead of repeating flags — see cli-and-config.md.

6. Prefer official docs for long platform snippets and CLI option details.

7. Keep host apps isolated from direct React Native APIs when possible (facade approach).

8. For startup/runtime verification, use agent-device to open the host app, navigate to the RN surface, capture snapshots/screenshots, and collect device evidence. If it is missing and verification needs it, install it through the environment's approved/trusted path or ask the user to install or enable it.

Canonical Docs

• Quick Start

• Expo Integration

• iOS Integration

• Android Integration

• Brownfield CLI

• Configuration

• Guidelines

• Troubleshooting

Path Selection Gate (Must Run First)

Before selecting any reference file, classify the project:

1. If no React Native app exists yet, use Expo creation path:

   • expo-create-app.md -> expo-quick-start.md

2. If React Native app exists, inspect package.json and app.json:

   • Expo if expo is present or Expo plugin workflow is requested.

   • Bare RN if native folders and direct RN CLI workflow are used without Expo path requirements.

3. If still unclear, ask one disambiguation question.

4. Continue with exactly one path.

When to Apply

Reference this package when:

• Implementing an accepted incremental migration from native-only apps to React Native or Expo

• Creating brownfield integration flows for Expo or bare React Native projects

• Performing initial setup with @callstack/react-native-brownfield

• Generating iOS XCFramework artifacts from a React Native app

• Generating and publishing Android AAR artifacts from a React Native app

• Integrating generated artifacts into host iOS/Android apps

Quick Reference

Problem -> Skill Mapping

Related Skills

• Assess React Native migration before selecting the migration path.

• brownie (shared host <-> RN state) and brownfield-navigation (typed RN -> native navigation) ship from another repo: invoke them by name, and fall back to the canonical docs if they are not installed.