cmux Backend

Core rules

• Default backend TypeScript to Effect under web/app/api/**, web/services/**, and backend scripts touching providers, databases, auth, rate limits, retries, timeouts, or telemetry.
• Keep Next route handlers thin: parse the request, run one Effect program at the boundary, map typed errors to HTTP responses, treat unexpected defects separately.
• Plain TypeScript is for trivial data shapes, constants, config files, frontend React, and small glue where Effect would add ceremony without improving failure handling.
• Cloud VM backend logic stays in Vercel route handlers and Effect services backed by Postgres. Do not reintroduce Rivet or a raw actor protocol unless a later architecture doc explicitly changes the control plane.
• Postgres is the source of truth for VM lifecycle, active VM limits, idempotency, and usage events.
• Production and staging Cloud VM Postgres use the Vercel Marketplace AWS Aurora PostgreSQL OIDC/RDS IAM path, with runtime env CMUX_DB_DRIVER=aws-rds-iam, AWS_ROLE_ARN, AWS_REGION, PGHOST, PGPORT, PGUSER, PGDATABASE.
• Run production/staging migrations with bun db:migrate:aws-rds-iam; never from Vercel build or route startup. Local dev keeps the CMUX_PORT-derived Docker Postgres path from bun dev.
• Cloud VM create pricing gates use Stack Auth team payment items when enabled.

Secrets

Cloud VM build, test, and local dev scripts read provider secrets from ~/.secrets/cmux.env: E2B_API_KEY, FREESTYLE_API_KEY, and the R2 upload vars web/scripts/build-cloud-vm-images.ts needs when creating Freestyle snapshots.