Codex for builders, in one page.
Codex is a coding agent: it reads your repo, plans, writes and edits code, runs commands and opens a pull request. Think of it as a fast, tireless junior who needs a clear brief and a careful review. It is leverage on well-defined work, not a replacement for your engineers and not a reason to skip the human check.
It earns its keep on bounded, checkable jobs you can describe and verify: adding tests, tidy refactors, a bug with clear repro steps, glue code, a small internal tool. Keep design, security-critical paths and ambiguous product calls with your people. Run a few tasks in parallel when they're independent.
- Goal: one clear outcome, written like a ticket for a capable junior.
- Context and files: the area to work in, plus how to build, test and lint.
- Done: the test that passes, the behaviour you expect.
- Out of scope: what to leave alone. Can't scope it tightly? Break it down or keep it yourself.
- Least privilege: the minimum access the task needs, no more. Prefer an isolated sandbox.
- Never expose production secrets. Use scoped, least-privilege tokens for any access.
- Secrets live in your secrets manager, never in the repo or the task description.
- Read every pull request like a contributor's. Green tests are a start, not a sign-off.
- Protect main: required status checks and a required human review before merge.
- Keep an AGENTS-style instructions file in the repo. It pays off on every task after.
- 1. ......................................................
- 2. ......................................................
- 3. ......................................................
Scope, run, review, merge. Tighten the brief or the context when something comes back off, and keep what works. Always a human on the diff.