BAND is wired for Google OAuth via Supabase, but the Supabase env vars aren't loaded yet. Two steps:

1. Enable Google in Supabase. Open Authentication → Providers on the BAND project, enable Google, paste a Google OAuth client ID + secret. Add this redirect to your Google OAuth client:https://iwvczfwgwbvaqkalmkgc.supabase.co/auth/v1/callback
2. Restart the dev server so it picks up the env vars already in .env.local:npm run dev

Need a Google OAuth client? Create one at console.cloud.google.com → Credentials → OAuth 2.0 Client ID → Web application.