reactreact/react-native/AGENTS.md

react-native

AGENTS.md127k starsChanged 5 months agoMITView on GitHub

A framework for building native applications using React. React Native is a monorepo: the react-native package, the packages published alongside it, and the apps and tooling used to develop them. Architecture notes live in docs directories beside the code they describe, indexed by docs/README.md. Treat them as reference for the subsystem you are working in, not as required reading. JavaScript CI is the lint, testjs, and buildjs_types jobs in .github/workflows/test-all.yml; Fantom and the native platforms have their own jobs. The…

We split this AGENTS.md into the rules it gives an agent

2 rules. About 0 are common, 2 are distinctive, and 0 are very specific to this project.

≈0
Common · estimate
Many files like this have a rule of this kind.
≈2
Distinctive · estimate
This author's own choices. Worth a look.
0
Very specific
Tied to their project's names, files or tools. Probably skip.

Common
Distinctive
Very specific
could be automatic: a setting could enforce it

Distinctive:
Never hand-edit generated output — change the source and regenerate.
line 59
Distinctive:
Keep each change focused — no unrelated refactors, formatting, or dependency updates.
line 69

≈ “Common” is an estimate: at least 1 in 5 of the 36,368 AGENTS.md files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.

Files

AGENTS.md

React Native

A framework for building native applications using React.

Repo structure

React Native is a monorepo: the react-native package, the packages published alongside it, and the apps and tooling used to develop them.

Path	Contents
`packages/react-native/Libraries`	JavaScript source (Flow) — the legacy location, with code gradually moving to `src/private`
`packages/react-native/src/private`	JavaScript source (Flow)
`packages/react-native/ReactCommon`	Shared C++ — Fabric renderer, TurboModules, JSI, Yoga, `jsinspector-modern`
`packages/react-native/ReactAndroid`	Android runtime (Kotlin, Java, JNI)
`packages/react-native/{React,ReactApple}`	Apple runtime (Objective-C++, Swift)
`packages/rn-tester`	RNTester — test app showcasing each core component and API, plus a `Playground` scratch surface
`packages/*`	Other published packages — Metro config, Codegen, ESLint config, dev-middleware, React Native DevTools frontend
`private/*`	Unpublished — the `helloworld` sample app, the `react-native-fantom` test runner
`scripts/*`	Repository tooling — build, test, release, and CI scripts

Architecture notes live in __docs__ directories beside the code they describe, indexed by __docs__/README.md. Treat them as reference for the subsystem you are working in, not as required reading.

Environment

Yarn v1, pinned via packageManager. Run commands from the repository root.
JavaScript work — lint, type checks, Jest, Metro — needs only Node and Yarn, on any platform.
Native builds need a platform toolchain: Xcode with CocoaPods or Swift Package Manager for iOS (macOS only), and the Android SDK and NDK with Gradle for Android. See Building from source.

Common commands

Command	Purpose
`yarn test <path>`	Jest unit tests, found in `__tests__` directories
`yarn fantom <path>`	Fantom integration tests, named `*-itest.js` — builds a native tester on first run
`yarn lint`	ESLint (`--max-warnings 0`)
`yarn flow-check`	Flow
`yarn format`	Format JavaScript/TypeScript, C/C++/Objective-C/protobuf, Kotlin, Java, Python, and Swift sources
`yarn format-check`	Check all repository formatting without changing files
`yarn format-<language>`	Format one language: `javascript`, `cpp`, `kotlin`, `java`, `python`, or `swift`
`yarn format-check-<language>`	Check one language without changing files

JavaScript CI is the lint, test_js, and build_js_types jobs in .github/workflows/test-all.yml; Fantom and the native platforms have their own jobs.

The formatting command uses pinned npm packages for Kotlin and Java and installs pinned Ruff through Python. To format every language, install a JDK with Java 17 or newer, Python 3 with pip, and a Swift 6.3 or newer toolchain in addition to Node and Yarn. Each language wrapper checks its own requirements and prints installation guidance when something is missing; yarn format then skips that language and continues formatting the others. Swift formatting accepts either swift-format or swift format from the installed toolchain.

Verification: Running RNTester

Needed only for changes that have to be seen running, such as user interface behavior.

yarn start serves RNTester over Metro at http://localhost:8081; yarn android builds and installs it on Android. Check the bundler with curl "http://localhost:8081/js/RNTesterApp.bundle?platform=ios&dev=true".

Gotchas

yarn install dirties the working tree: a preinstall hook (scripts/try-set-hermes-compiler-prebuilt.js) resolves the hermes-compiler placeholder in packages/react-native/package.json (0.0.0 → a real version) and touches yarn.lock. Expected — do not commit it.
Metro cannot bundle until codegen is built once — yarn --cwd packages/react-native-codegen build. Without it, bundling fails with Cannot find module '@react-native/codegen/lib/parsers/flow/parser'. Every other package runs from source — yarn build is not needed for development (see scripts/build/README.md).

Generated code

Never hand-edit generated output — change the source and regenerate. CI validates the committed snapshots.

Native modules and components are declared by JavaScript specs (Native*.js, *NativeComponent.js); their native counterparts are generated at build time.
Feature flags are declared in packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js; yarn featureflags regenerates the JavaScript, Java, and C++ accessors.
JavaScript sources are typed with Flow, and the public API is exported from packages/react-native/index.js. TypeScript types are generated from those sources, and packages/react-native/ReactNativeApi.d.ts is a committed snapshot of that API — run yarn build-types to regenerate both whenever the public API changes, then yarn test-generated-typescript to type-check the result.
The public native API is snapshotted as well: C++ under scripts/cxx-api (yarn cxx-api-build), and Android in packages/react-native/ReactAndroid/api/ReactAndroid.api.
CHANGELOG.md is compiled at release time from pull request descriptions.

Contributing guidelines

Keep each change focused — no unrelated refactors, formatting, or dependency updates.
Complete the pull request template — the motivation and the user-visible effect, and a changelog entry with its category and type tags.
In the test plan, give the exact commands you ran and their results, plus screenshots or a video for user-interface changes. Say which checks you could not run.

The full process is on reactnative.dev.

Download now (ZIP)

Oct 13, 2026React Native — en.wikipedia.org
Oct 8, 2026What is React Native — Articles — expo.dev
Mar 20, 2026How to Boost Your App Ratings with React Native In- ... — medium.com
Oct 20, 2024React Native vs Dual Native: I Learned Both So You Don't ... — medium.com
May 15, 2022Review of React Native Expo – Welcome to my Tech Talk — blogs.oregonstate.edu

2 more on the web

Dec 31, 2019A Year of React - 2019 in Review — dev.to
Sep 9, 20184 reasons why you should use React Native for your next MVP — madhavanmalolan.medium.com

On YouTube · 1

Sep 17, 2026접히는 아이폰이 왔는데 앱은 그대로 둬도 될까? — 크로스플랫폼 코리아474 views

On Bluesky · 1

Sep 11, 2026Here is the fucking source code, read it: github.com/react/react-... — @rwruedii.bsky.social0 likes and reposts · 2 replies

Other versions1 project uses a version of this.
Word for word · 1
react-native-tvos/react-native-tvos★ 1.4k100% same
Edited · 0
None found.
Wrote their own version · 0
None found.
How matches are found. Word for word: the exact same text. Edited: shares passages with this file (“99% same” means 99% of its five-word phrases also appear here; 10% or more counts). Their own version: similar meaning, or, weakest, the same name. We can’t tell which project had it first. Projects are counted among the 200 most-starred candidates, and mentions are links to the repository we found, up to 50 per site, so both counts are a floor.
Where files are headingNew AGENTS.md files have more rules about keeping secrets out of the code, and fewer about code style.
Of the AGENTS.md files we read, the 28,693 first seen in the last six months, against the older ones: the kind of rule that gained most share, and the kind that lost most. About files like this in general, not this one, and an estimate, since a kind is a pattern in the words.

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