codex-cli

The golden rule: Codex's self-report is a claim, not the truth. Always capture its output, then independently verify the artifacts yourself (read the files, re-run the tests) before treating the task as done.

Verified available on this machine: codex-cli 0.137.0, logged in via ChatGPT (no API key needed). Confirm with codex login status.

codex exec \
  --cd <workdir> \
  --sandbox <read-only|workspace-write|danger-full-access> \
  -o /tmp/codex_<rand>.txt \
  "your metaprompt here"  2>>/tmp/codex_<rand>.log

• Prompt as the final arg, OR pipe via stdin: echo "$PROMPT" | codex exec - (good for long/generated prompts). If both are given, stdin is appended.
• -o, --output-last-message <file> — writes ONLY Codex's final message to a file. This is your clean capture; read it back, don't scrape the TUI stream.
• 2>>/tmp/...log — Codex streams progress/reasoning to stderr; the final message goes to stdout. Redirect stderr to a log so it doesn't bloat your context. Generate the suffix with openssl rand -hex 4.
• --cd <dir> — Codex's working root. Scope it to the relevant subdir (e.g. apps/api), not the whole monorepo, so it stays focused.
• --skip-git-repo-check — only needed when running outside a git repo.

• read-only (default) — Codex can read/grep/run read-only commands but cannot edit files or hit the network. Use for review, analysis, planning, "find the bug", second opinions.
• workspace-write — can edit files in --cd (and --add-dir paths) and run commands, but no network by default. Use for real implementation/refactors.
• danger-full-access — no sandbox at all. Avoid; only for throwaway/ephemeral dirs you fully control.

Approvals: in exec mode Codex does not prompt for approvals. For a fully autonomous run with no gating at all, add --dangerously-bypass-approvals-and-sandbox. This is powerful — only use it when the user has explicitly authorized autonomous edits AND the --cd is scoped, or when running in an already-sandboxed/throwaway dir. When unsure, ask the user which sandbox tier before running with write access.

codex exec resume --last "now also update the tests"   # most recent session
codex exec resume <session-id> "..."                   # a specific one

The session id is printed at the start of each exec run. Use resume for multi-turn delegation (draft → refine → fix) instead of re-sending all context.

1. Delegate — codex exec ... -o <out> 2>><log>.
2. Capture — read <out> (and <log>/--json if you need detail).
3. Verify INDEPENDENTLY — do not trust Codex's "tests pass" / "done":
   • git status / git diff to see what actually changed.
   • Read the changed files yourself.
   • Re-run the build/tests/linter yourself and read the real output.
4. Iterate — if wrong, codex exec resume --last "<correction>" and repeat.
5. Report — tell the user what changed, what you verified, and how. State plainly when something failed or was skipped.

Cleanup: remove /tmp/codex_* capture/log files (and any throwaway worktrees) when done.