F1 Predictor

Prediction league for Formula 1 fans. Friends predict race weekend results before qualifying starts, and the app scores them automatically once results are in.

Work in progress.

Running locally

Requires Node.js 24 (see .nvmrc and engines in package.json, which Vercel reads).

npm install
npm run db:migrate # apply migrations to the database in DATABASE_URL
npm run dev        # http://localhost:3000

Environment variables

The app reads its secrets from environment variables. Locally, put them in .env.local (ignored by git). On Vercel, set them in the project settings.

Variable	What it is
DATABASE_URL	Postgres connection string from Neon. The Neon integration on Vercel sets it.
BETTER_AUTH_SECRET	Random secret that signs session cookies, at least 32 characters: openssl rand -base64 32.
BETTER_AUTH_URL	The app's own URL: http://localhost:3000 locally, the production URL on Vercel.
GOOGLE_CLIENT_ID	OAuth client ID from Google Cloud Console (APIs & Services → Credentials).
GOOGLE_CLIENT_SECRET	Secret of the same OAuth client.
APP_ADMIN_EMAILS	Comma-separated emails of the App Admins, who create the League and refresh the calendar at /admin.

The Google OAuth client needs <BETTER_AUTH_URL>/api/auth/callback/google as an authorized redirect URI, for every URL the app signs in from. Preview deploys have changing URLs, so sign-in works on production and locally.

Database

Postgres on Neon, accessed with Drizzle (ADR-0004). The schema is in src/db/schema.ts and the SQL migrations generated from it are in drizzle/.

npm run db:generate # after changing the schema: write a new migration to drizzle/
npm run db:migrate  # apply pending migrations to DATABASE_URL

Tests run against PGlite, an in-memory Postgres, with the same migrations (src/db/test-database.ts), so they need no database server.

Checks

These are the same checks CI runs on every push and pull request:

npm run typecheck  # TypeScript, after generating Next.js route types
npm run lint       # ESLint
npm test           # Vitest, single run

npm run test:watch reruns tests on file changes.

Deployment

The app is deployed to Vercel at https://f1-predictor-omega.vercel.app/: main goes to production, and every pull request gets a preview deploy.

Production deploys apply pending migrations to Neon before building (buildCommand in vercel.json); a failed migration fails the deploy. Preview deploys skip migrations, so a pull request never changes the production database.