cmux-backend

name: cmux-backend description: "Backend TypeScript and Cloud VM development rules for cmux. Use when editing web/app/api, web/services, backend scripts, Cloud VM lifecycle, provider integrations, Postgres, Stack Auth pricing gates, migrations, or provider image build scripts."

cmux Backend

Use this skill for backend TypeScript, Cloud VM, provider, database, auth, rate-limit, retry, timeout, or telemetry work.

Core rules

• Default backend TypeScript to Effect under web/app/api/**, web/services/**, and backend scripts that touch 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, and treat unexpected defects separately.
• Use plain TypeScript only for trivial data shapes, constants, config files, frontend React code, or small glue where Effect would add ceremony without improving failure handling.
• Cloud VM backend logic must stay in Vercel route handlers and Effect services backed by Postgres.
• Do not reintroduce Rivet or a raw actor protocol for Cloud VM unless a later architecture doc explicitly changes the control plane.
• Production and staging Cloud VM Postgres use the Vercel Marketplace AWS Aurora PostgreSQL OIDC/RDS IAM path.
• Runtime env names are CMUX_DB_DRIVER=aws-rds-iam, AWS_ROLE_ARN, AWS_REGION, PGHOST, PGPORT, PGUSER, and PGDATABASE.
• Run production/staging migrations with bun db:migrate:aws-rds-iam; never run Drizzle migrations from Vercel build or route startup.
• Local development keeps using the CMUX_PORT-derived Docker Postgres path from bun dev.
• Cloud VM create pricing gates should use Stack Auth team payment items when enabled.
• Postgres remains the source of truth for VM lifecycle, active VM limits, idempotency, and usage events.

Secrets

Cloud VM build, test, and local dev scripts use provider secrets from ~/.secrets/cmux.env.

• E2B_API_KEY
• FREESTYLE_API_KEY
• R2 upload vars used by web/scripts/build-cloud-vm-images.ts when creating Freestyle snapshots

Load them with:

set -a
source ~/.secrets/cmux.env
set +a

~/.secrets/cmuxterm-dev.env is for local Stack/web env and does not contain the provider build keys. bun dev sources ~/.secrets/cmux.env first when present, then ~/.secrets/cmuxterm-dev.env so cmuxterm-specific Stack settings override broader cmux secrets. The web dev loader still accepts the legacy ~/.secret/cmuxterm.env and ~/.secrets/cmuxterm.env paths while machines migrate.

Detailed references

• Read references/effect-boundaries.md when shaping route handlers, services, typed errors, retries, or dependency injection.
• Read references/cloud-vm-control-plane.md when touching VM lifecycle, migrations, Postgres, provider idempotency, or pricing gates.