TL;DR: I wired OpenAI's Codex CLI into Claude Code as an adversarial reviewer with a convergence loop. Then I pointed the loop at its own implementation. It failed the review three times before passing, and every single failure was a real bug. Here's the whole story, with the prompts and shell recipes you can steal.
The tweet that started it
A while ago Siqi Chen posted his favorite way of working with frontier models:
step 1. ask it to write a plan
step 2: "please get second opinions from codex CLI using gpt-5.6-sol @ max effort and kimi CLI using kimi 3. Revise your plan with any sound findings. repeat until convergence or up to 5 rounds."
