Express on port 3001 serves **both** the API and the production frontend build:
- API routes: `/api/*` — handled by Express route handlers
- Frontend: everything else — served as static files from `frontend/build/`
There is no separate frontend server in production. The React dev server (`npm start` on port 3000) is only for local development with hot-reload. In production and on the dev server, you must run `npm run build` in `frontend/` after any frontend code change, then restart the backend.
**After editing frontend source files:**
```bash
cd frontend && npm run build # Compile new bundle into frontend/build/
# Then restart backend (or it will serve the new static files on next request)
```
The CI/CD pipeline handles this automatically — `build-frontend` stage runs before deploy.
## Common Commands
### Backend
```bash
cd backend
node setup.js # Initialize DB, tables, indexes, default admin user
node server.js # Start backend on port 3001 (serves API + frontend build)
```
### Frontend
```bash
cd frontend
npm install # Install dependencies
npm run build # Production build → frontend/build/ (REQUIRED after code changes)
npm start # Dev server on port 3000 (local dev only, NOT used in production)
npm test # Run tests (react-scripts test)
```
### Both servers (from project root)
```bash
./start-servers.sh # Start backend + frontend in background
./stop-servers.sh # Stop all servers
```
### Database Migrations (run from `backend/`)
```bash
node migrations/run-all.js # Runs all migrations in order (idempotent)
```
### Python Scripts (from `backend/scripts/`)
```bash
# Compliance xlsx parsing (called automatically by upload flow)
The frontend ESLint config enforces `no-unused-vars` as a warning. The CI pipeline fails if warnings exceed 25. To avoid lint failures:
- **Prefix intentionally-unused variables with `_`** — this suppresses the warning. The `varsIgnorePattern: "^_"` and `argsIgnorePattern: "^_"` rules are configured in `frontend/package.json`.
- Common patterns:
-`const [_unused, setFoo] = useState(...)` — destructured value you don't need
-`const _legacyRef = useRef(...)` — kept for future use
- **Do not leave variables unprefixed if unused.** Either use them, remove them, or prefix with `_`.
- This applies to all frontend code written by the agent.
### Backend
No ESLint is configured for backend — the pipeline uses `node -c` syntax checking only. Keep code clean but there is no automated unused-var enforcement on the backend side.
