> ## Documentation Index
> Fetch the complete documentation index at: https://supastack.dev/llms.txt
> Use this file to discover all available pages before exploring further.
> For the full documentation corpus in one file, fetch: https://supastack.dev/llms-full.txt

# Configure the mobile app

Set the backend address and deep-link scheme the native build uses, and keep both sides of the handoff in sync.

## Setup and configuration

Put device-facing values in `apps/mobile/.env.local`; Expo reads that file, not the repository-root `.env`. `EXPO_PUBLIC_API_URL` is the Web backend origin the phone can reach — the same value you tested in the phone browser. `EXPO_PUBLIC_APP_SCHEME` is the app's native URI scheme; use a reverse-DNS value such as `com.example.app`.

`app.json` owns the product name, slug, version, bundle identifier, and plugins. `app.config.ts` derives the deep-link scheme and production origins from `EXPO_PUBLIC_APP_SCHEME`, so a scheme change needs a native rebuild, not only a Metro restart. On the server, add every origin the app will use to `MOBILE_ALLOWED_ORIGINS`; the handoff fails closed when the two sides disagree.

Every `EXPO_PUBLIC_*` value is bundled into the app. Keep provider keys on the server and use public values only for addresses and schemes.

```
EXPO_PUBLIC_API_URL=http://192.168.1.25:3000
EXPO_PUBLIC_APP_SCHEME=com.example.app
```


## Implementation workflow

Restart Expo after changing `.env.local`. Run the package tests and typecheck, then confirm the resolved scheme with a development build: open an auth callback link and check that it returns to the app instead of the browser. Expo Go cannot validate custom schemes belonging to your native build.


## Verification and troubleshooting

Restart Expo after changing `.env.local` and open the preview on the target device. Change the theme, restart the app, and confirm the choice persists; then trigger a deep link and check that the app routes it instead of the browser.


If you want to continue setup, read [Test the mobile app](https://supastack.dev/docs/mobile/testing.md).


## Next

[Test the mobile app](https://supastack.dev/docs/mobile/testing.md)