About

App&Flow is a Montreal-based React Native engineering and consulting studio. We partner with the world’s top companies and are recommended by Expo. Need a hand? Let’s build together. team@appandflow.com

Stim

Fast, isolated local React Native environments for coding agents.

Stim gives each project or git worktree its own Metro port and owned simulator or emulator. It shares native artifacts, Xcode compilation data, Gradle output, and Metro transforms across worktrees. Agents can work in parallel without sharing live resources, then clean up every resource Stim created.

Stim supports React Native Community CLI and Expo projects. Builds run locally. Apps can launch on owned simulators and emulators, connected physical devices, or configured remote devices.

Install

The stim npm package installs the stim command. If you previously installed stim-cli globally, run npm uninstall --global stim-cli first.

npm install --global stim
npx skills add appandflow/stim

Run without a global install when needed:

npx stim <command>

Then ask your coding agent to build and run the app. The normal loop is:

stim doctor
stim start
stim ios                  # or: stim android
stim logs --errors
stim stop

stim reload [ios|android] is a recovery or explicit restart command. Use it after a failed first bundle load or when an error screen remains after a fix, not after every JavaScript edit.

Stim needs no project initialization. Runtime state stays under ~/.stim by default.

For an isolated branch, create the worktree with Git, then warm it:

git worktree add -b feature/settings ../feature-settings HEAD
cd ../feature-settings
stim worktree warm

If a harness already created the linked worktree, run only stim worktree warm there. Warm copies missing ignored state from main, including eligible .env and local configuration files. Existing entries are preserved; existing ignored directories such as node_modules are skipped whole.

After the work is preserved, stim worktree remove removes any linked worktree, warmed or not. Git-created branches stay. See the worktree guide for exclusions and cleanup rules.

Documentation

Read the Stim documentation for the motivation, setup, concepts, command reference, and settings reference.

The installed version also includes its own reference:

stim guide agent
stim guide
stim guide lifecycle
stim guide settings

Packages

• stim provides the stim command.
• @stim-cli/metro shares Metro transforms and records logs.
• @stim-cli/expo-build-cache lets direct Expo builds share native artifacts with Stim.
• @stim-cli/cache holds the cache provider contract and the local-first tier coordination behind both caches.
• @stim-cli/core contains shared internal cache contracts.

Development

pnpm install
pnpm build
pnpm test
pnpm typecheck
pnpm lint

Stim is licensed under the MIT License.