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Expo Brownfield

ExpoOfficialPublished by Expo

  • Skill
  • Tool integration
  • Software development
  • MIT
  • Low risk
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From the author

Integrate Expo and React Native into an existing native iOS or Android app. Use for brownfield, embedding a React Native screen in SwiftUI/UIKit or Kotlin, or AAR/XCFramework packaging. Covers isolated and integrated approaches. For building or distributing a purely native app with EAS, use eas-app-stores.
— the description by Expo

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

The expo-brownfield skill provides a structured methodology for adopting React Native incrementally within established native mobile applications. It outlines two primary integration strategies: the isolated approach, which packages React Native code as a prebuilt library (AAR or XCFramework) for teams that want to avoid Node.js dependencies in the host app, and the integrated approach, which incorporates React Native directly into the native build system (Gradle or CocoaPods) for unified development. The skill emphasizes careful host inspection, version compatibility, and feature validation to ensure seamless interoperability between native and React Native components.

What it does

  • Guides the integration of React Native features into existing native iOS and Android codebases.
  • Defines the isolated approach for consuming React Native as a prebuilt library dependency.
  • Defines the integrated approach for embedding React Native directly into native build pipelines.
  • Provides criteria for selecting the appropriate integration strategy based on team structure and build requirements.
  • Outlines prerequisites for environment setup, including Node.js and native build toolchains.
  • Details verification steps to ensure feature functionality and lifecycle management within the host app.

When to use it

  • When adding new features to an existing native app using React Native.
  • When native and React Native teams operate on different release cadences.
  • When you need to minimize the footprint of React Native on the native build pipeline.
  • When a single team owns both native and React Native code and prefers a unified build.

Advantages

  • Supports incremental adoption of React Native in legacy native applications.
  • Offers flexibility to choose between isolated and integrated build workflows.
  • Enables native teams to consume React Native features without requiring Node.js tooling.
  • Maintains compatibility with existing native navigation and UI patterns.
  • Supports standard development workflows like Metro and Fast Refresh.

Usage examples

“How do I add a React Native screen to an existing native Android app without requiring the Android team to install Node.js?”
The agent will guide you through the isolated approach, creating an Expo project and building it as an AAR artifact that the native Android team can consume as a standard dependency.
“We want to integrate Expo into our iOS app and manage everything in one repository. Which approach should I use?”
The agent will recommend the integrated approach, providing steps to add React Native and Expo directly to your CocoaPods setup while preserving your existing native project structure.

Install

  1. Download the skill as a ZIP:

    https://autogineer.com/agent-skills/expo/expo-brownfield/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip expo-brownfield.zip -d .agents/skills

Documentation by Expo

Expo Brownfield

A brownfield app is an existing native iOS or Android app that adopts React Native incrementally, as opposed to a greenfield app that is React Native from day one.

Inspect the host first

Identify the existing app entry point, navigation owner, native build system, deployment targets, and any React Native runtime already linked. Record the installed Expo, React Native, and brownfield package versions from the lockfile. Adding EAS Build or Submit to a Swift app alone does not require React Native; route that task to eas-app-stores.

Preserve the host's SwiftUI App / UIKit window and native screens when embedding a feature. Do not run prebuild in a manually maintained native host, including during troubleshooting. An isolated Expo producer may use CNG; keep its generated ios/ and android/ separate from the consuming app.

Expo supports two distinct ways to add React Native to a brownfield project:

ApproachWhat ships to the native appWhen to choose
IsolatedPrebuilt AAR / XCFrameworkNative team doesn't need Node or RN tooling; RN code can live in a separate repo
IntegratedReact Native sources added to the existing Gradle / CocoaPods buildOne team owns everything; comfortable with RN tooling; wants a single build

For the full decision matrix, see ./references/comparison.md.

Pick an approach

Use these quick rules — fall through to comparison.md for anything ambiguous.

  • Choose isolated if the iOS/Android team must consume RN as a regular library dependency (AAR or XCFramework), without installing Node, Yarn, or the React Native build toolchain.

  • Choose isolated if RN code and native code live in separate repositories or release on independent cadences.

  • Choose integrated if a single team owns both the native and RN code and is willing to add React Native + Expo to the native project's Gradle and CocoaPods setup.

  • Both approaches support Metro and Fast Refresh in Debug. Choose integrated for shared build ownership, not because isolated lacks live JS iteration.

References

  • ./references/brownfield-isolated.md -- Build RN as AAR/XCFramework and consume from the native app (BrownfieldActivity, ReactNativeViewController, ReactNativeView)

  • ./references/brownfield-integrated.md -- Add RN and Expo directly to existing Gradle and CocoaPods builds, preserving the native app shell

  • ./references/feature-integration.md -- Pass input, return results, dismiss, clean up listeners, and forward lifecycle events; includes a SwiftUI host example

  • ./references/comparison.md -- Decision criteria, trade-offs, and scenario mapping for choosing an approach

  • ./references/troubleshooting.md -- Metro connection, build, signing, and module-resolution issues common to both approaches

More information available at https://docs.expo.dev/brownfield/overview/

Shared prerequisites

Both approaches require, in the environment that builds the React Native side:

  • Node.js (LTS) — runs the Expo CLI and JavaScript code.

  • The project's package manager and lockfile — npm, Yarn, pnpm, or Bun. Do not switch package managers just to follow an example.

The iOS build environment needs Xcode and CocoaPods (use the project's Gemfile/Bundler setup when present). The isolated consuming app needs Xcode but no CocoaPods or RN tooling just to consume the artifacts.

Select compatible versions

For an existing Expo/RN project, keep its selected SDK and use npx expo install to align dependencies. Do not upgrade it just to follow this skill. For a new producer, use the current stable SDK compatible with the host's OS support, dependencies, and build toolchain; confirm the release is stable before selecting it.

Before native setup, read ./references/version-compatibility.md for matching native templates, toolchain/OS requirements, and build defaults across SDK versions. A purely native consumer has no Expo SDK version to pin, but must satisfy the artifact's requirements.

Verify the feature in the host

Open the RN screen with input, return a result to native, dismiss, and reopen with fresh input. Check listener cleanup and the host's original navigation. Then build the host in Release with a Release artifact and Metro stopped. Rendering only in Expo Go or the producer's example app does not validate the integration. See ./references/feature-integration.md for the complete acceptance scenario.

Submitting Feedback

If you encounter errors, misleading or outdated information in this skill, report it so Expo can improve:

npx --yes @expo/agent-cli@latest feedback --category skills --subject "expo-brownfield" "<actionable feedback>"

Only submit when you have something specific and actionable to report. Include as much relevant context as possible. If an agent repeatedly fails at an Expo task or the user has to step in, submit a brief report of the task, expected result, and what went wrong using --category evals and the relevant Expo package or command as --subject.

Files

references/version-compatibility.md

Select versions before integrating

Keep the workflow version-aware rather than pinning every host to one SDK. Existing projects retain their SDK unless an upgrade is part of the task. New producers should use the current stable Expo release when the host and toolchain can support it.

Inspect and select

  1. Read the producer's package.json and lockfile; record resolved expo, react-native, and expo-brownfield versions. Check the host's deployment targets, Xcode/Node versions, and native dependency graph, including any existing RN runtime.

  2. For new work, check the Expo releases and SDK compatibility table. npm view expo dist-tags --json can confirm the current stable latest version. Do not infer stability from the highest SDK number or select canary/next by default.

  3. Select an SDK compatible with the host's supported OS versions, modules, and build tools. Do not silently raise the host's minimum OS or swap its toolchain to satisfy a tutorial. If a constraint conflicts, explain the concrete choices before changing that product requirement.

  4. Use that SDK's versioned Brownfield API docs and sdk-<major> native template. Install modules with npx expo install; run npx expo install --check before native builds. For an SDK upgrade, use expo-upgrade, preserve the host, and apply native diffs selectively.

  5. Inspect the installed CLI's build:ios --help / build:android --help, plugin schema, generated Swift/Kotlin wrappers, and Package.swift. Flags, prebuilt defaults, import names, and binary products can change within a major release.

To scaffold a small new feature after those checks:

npx create-expo-app@latest my-project --template blank@latest
cd my-project
npx expo install expo-brownfield typescript @types/react

This avoids adding a Router shell just to export one component. For an existing Router app, preserve it and add the root-props adapter described in feature integration. If selecting an older SDK, use a verified template tag such as blank@sdk-55; the scaffolder's own @latest version does not determine the template's SDK. Commit the producer's lockfile for repeatable builds.

SDK requirements and build defaults

SurfaceSDK 55SDK 57
React Native family0.830.86
iOS minimum in the Expo template15.116.4
Documented minimum Node / Xcode20.19.x / 26.222.13.x / 26.4
Brownfield React Native build defaultSourcePrebuilt
Precompiled Expo modulesVersion/configuration dependentEnabled by default in the native template
Swift Package products55.0.28: separate feature and Hermes products57.0.18: one aggregate product when precompiled modules are detected; otherwise separate products

React Native prebuilt binaries and precompiled Expo modules are separate settings. Set React Native source mode on expo-brownfield's ios.buildReactNativeFromSource. Expo module precompilation is controlled by expo-build-properties' ios.usePrecompiledModules. Do not disable defaults as a generic build fix; first inspect the failing dependency and toolchain requirement.

In 57.0.18, precompiled builds suffix the generated package/product with its configuration (MyAppPackage-release or MyAppPackage-debug). They do not rename the generated Swift module: continue to import the configured target, such as MyBrownfield. Inspect the emitted manifest instead of constructing an assumed package path.

SDK 56 introduced additional brownfield capabilities carried into SDK 57, including experimental multiple isolated frameworks and registering host Turbo Module classes. Load the selected SDK's API and installed interfaces only when the task needs them. Do not enable experimental multi-framework support for a single feature or assume two independently packaged RN runtimes can be linked together without collision handling.

Sources: SDK requirements, SDK 57 Brownfield API, SDK 57 native template, SDK 56 brownfield additions, published Brownfield package.

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs Node.js

Security

What our scanner noticed· Low risk

  • Instructions that use the network

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Attribution and licence

Published by
Expo
Publisher
Expo (Official)
Source
expo/skills · plugins/expo/skills/expo-brownfield · commit a9e5bd3
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from plugins/expo/LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
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Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download expo-brownfield.zip