Several posts ago, I wrote about setting up a multi-agent adversarial code review process as part of my development pipeline. The premise came from a podcast: if one frontier model is writing the code, you want a different lineage model doing the review. I'd already been running an informal version of this: just Claude Code reviewing Claude Code with an adversarial prompt. It had shockingly good luck catching real problems. Good enough that I stopped trusting the vibe and decided to go get actual data.
So here's what I set up. Claude Code wrote the PRs. Every PR got reviewed automatically by 2 reviewers running in parallel through GitHub Actions: Claude Code with an adversarial prompt and Gemini with an adversarial prompt. I read everything myself. Then the same Claude Code agent that had written most of the PRs pulled both reviewers' feedback locally and distilled it into a scored ledger, PR by PR, for 6 weeks.
Wiring Claude Code to review PRs through a GitHub Action was trivial. Wiring Gemini up the same way was not. Claude Code could not figure out how to get the Gemini CLI working inside a GitHub Action, and I ended up installing the Gemini CLI locally and having it perform the wiring.
