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Use case

Verify that an agent can author and run TypeScript code end to end: write sources, install deps, compile, start a long-running server, smoke-test it with curl — all inside a Node 20 sandbox.

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Template

node — Node 20, npm, TypeScript, tsc on PATH. No pip, no Python.

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Run it

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Security policy

The server the agent writes binds to 127.0.0.1 inside the VM and is only reachable with curl from within the same sandbox — outbound network policy doesn’t need to allow it because nothing outside the VM is trying to reach it.

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Env isolation

The generated server.ts reads both from process.env, so rotating the port or service name is a client-side config change, not a prompt rewrite.

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What the agent does

  1. mkdir -p /workspace/api && cd /workspace/api.
  2. Write server.ts reading process.env.API_PORT and process.env.SERVICE_NAME.
  3. npm init -y && npm i express && npm i -D typescript @types/node @types/express.
  4. npx tsc to compile.
  5. Start the server in background: node server.js >server.log 2>&1 &.
  6. sleep 1 && curl http://127.0.0.1:$API_PORT/health.
  7. Return the JSON plus tail -n 10 server.log.

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Why background processes matter

session._inner._sbx.run_command("... &") returns when the shell forks — the server keeps running in the sandbox. The same session can then hit it with a second run_command("curl ..."). This is the same pattern you’d use for testing any long-running service (databases, workers, APIs) against an agent-driven client.

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Full source

See cookbook/examples/openai-agents-typescript-api/main.py in the repo.