Codex

Use your own locally-installed OpenAI Codex CLI as the pipeline's LLM — no API key, no per-token billing. Runs bill against the ChatGPT Plus/Pro subscription you're already paying for.

This is the Codex twin of Claude Code. The two are fully independent: use either, both, or neither, and turning one on or off never affects the other.

Built in — nothing to install, nothing to restart. The app detects the CLI and its login state on its own.

Setup

Install the CLI: npm install -g @openai/codex (or the Homebrew package on macOS).
Log in with your ChatGPT account:
```
codex login
```
Open Settings → Providers & models. The Codex row detects the CLI and whether you're signed in.
Route individual phases to it in the routing rows, or pick a subscription rung in guided routing to put every phase on it at once.

Warning

Make sure OPENAI_API_KEY is not set in your environment or .env. Tomes strips it from the CLI's environment so Codex always uses your subscription login — an API key present there would silently switch you to per-token billing.

Model selection

The default model id default defers to whatever the CLI currently ships as its default, so CLI upgrades are inherited without a change here. You can pin a specific model (gpt-5-codex, gpt-5, gpt-5-mini, o3) per phase in the routing rows.

Usage limits, pausing, and resuming

ChatGPT subscriptions meter usage in rolling windows.

Streamlined

Exhausting your window mid-run is not a lost run. When Codex reports the window is spent, the pipeline pauses itself and saves a checkpoint — the run appears in the paused-runs banner marked quota hit. Resume from the banner once your window resets and it picks up at the exact chunk it stopped on.

Notice

Codex's limit messages include a human-readable reset time (shown in the error toast) but no machine-readable timestamp, so the app cannot count down to the reset for you.

Privacy and safety notes

Prompts are sent to the CLI via stdin, never via shell arguments.
The CLI runs in a scratch directory with --sandbox read-only — it cannot write to your project or vault.
The app never sees or stores your ChatGPT credentials; codex login state lives wherever the CLI keeps it.

Known limitations

Notice

Marked experimental. The Codex CLI's non-interactive JSON output is under-documented, so an unusual CLI version may need this integration updated before it works.

The refusal-repair path (built for Claude Code's occasional content refusals) does not yet cover Codex — a refusal surfaces as a plain chunk error instead of being automatically repaired.