How do you mean OpenAI lets you use your own harness? I'm under the impression that a custom harness requires the OpenAI SDK, which requires api tokens rather than plus/pro accounts.

https://x.com/thsottiaux/status/2058071172361998482

"A little secret. About 5% of our production traffic is on the Pi harness, about another 5% is on OpenCode. Reminder you can use your ChatGPT account in a flourishing set of other tools.

We’ll continue to make Codex awesome, but you have options."

Not just harnesses, you can even use the subscription in CI/CD. That, plus the fact that web chat does not count toward the same limits, is why I think the Codex personal plan is easily 10x the value of Claude Code.

https://developers.openai.com/codex/auth/ci-cd-auth

You must've missed the OpenAI's response to Anthropic forcing everyone to their own harness if they want subscription pricing: official endorsement of custom harnesses like opencode and pi even when used with Codex subscription.

I think they even partnered with opencode or something like that (don't remember).

Anthropic is the one that prohibits harnesses other than Claude Code on subscription plans and bans users for disobeying.

OpenAI officially allows that with subscriptions.