translita

Transee

An offline-first mobile translation app built with Expo, React Native and TypeScript.

Status: Day 1 of 20. The foundation, design system and navigation are in place. Translation, OCR, voice and offline models are intentionally not implemented yet – see docs/ROADMAP.md.

Getting started

npm install
npm start          # then press "a" for Android

Or launch Android directly:

npm run android

Connecting real translation

Translation runs through a small backend in server/, which holds the provider credential. The app only ever knows the backend URL.

With no backend configured the app uses its built-in sample engine, so it runs out of the box. To use real translation:

cd server && npm install
cp .env.example .env      # add your Azure Translator key
npm run build && npm start

Then point the app at it and restart the dev server:

EXPO_PUBLIC_TRANSEE_API_URL=http://<your-host>:8787 npx expo start

No Azure account? Run the backend’s deterministic stand-in instead:

cd server && TRANSLATION_PROVIDER=fake npm start

EXPO_PUBLIC_* values are inlined into the app bundle and are public. Only the backend URL belongs there — never a provider key. See server/README.md.

Backend URL for EAS builds

EAS builds run on EAS’s machines and never see a local .env. Each build profile in eas.json names the EAS environment it takes variables from — preview and production, so the two are configured independently and a staging backend can never be baked into a store build.

The URL itself is not in this repository. Set it once per environment after the backend is deployed:

eas env:create --scope project --name EXPO_PUBLIC_TRANSEE_API_URL \
  --value "https://<your-backend-host>" --environment preview --visibility plaintext

Repeat with --environment production. Check what a profile will build with using eas env:list --environment preview.

Plaintext, not secret. EAS withholds secret-typed variables from the bundler, so marking this one secret would silently produce a build with no backend — and it is public by design anyway. Nothing secret may ever be an EXPO_PUBLIC_* variable.

The value is inlined at build time, so changing the backend URL needs a new build. Prefer a domain you control over a hosting provider’s default hostname; moving hosts later then costs a DNS change rather than shipping a new binary to every user.

With no variable set the build is simply unconfigured: the online engine reports itself unavailable and no request is attempted.

Scripts

Command	Purpose
npm start	Expo dev server
npm run android	Build and run on Android
npm run ios	Build and run on iOS (macOS)
npm run web	Run in the browser
npm run typecheck	tsc --noEmit
npm run lint	ESLint
npm run format	Prettier write
npm test	unit tests
npm run check	typecheck + lint + format check + test

Structure

app/                Expo Router routes (one-line re-exports)
  (tabs)/           Translate, Camera, History, Settings
  translate/        Language picker
  camera/           Scan result
  history/          History detail
  settings/         Offline language packs
src/
  components/       Design system (ui/ + layout/)
  features/         translation, offline, camera, voice, history, settings
  services/         Service interfaces and placeholders
  store/            Preferences and language-pair providers
  database/         Schema, migrations, Database/Repository seams
  hooks/            useTheme, useDebouncedValue
  utils/            Result, formatting, ids, logging
  constants/        Design tokens, config, language reference data
  types/            Shared domain types
assets/
docs/

Docs

• Architecture
• Design system
• Conventions
• Roadmap

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