How I Made Claude Code and GPT-5.4 Review Each Other's Code

The Problem: Same Model Writes and Reviews When Claude Code writes code and Claude reviews it, you get the AI equivalent of grading your own homework. Blind spots survive. I wanted GPT-5.4 to review Claude's code from a genuinely different perspective. So I built helix-codex — an MCP server that bridges Claude Code (Opus 4.6) to Codex CLI (GPT-5.4). What Makes It Different There are 6+ Codex MCP bridges on GitHub. They all do the same thing: call codex exec , return raw text. Claude has no idea what happened inside. helix-codex parses the entire JSONL event stream and returns a structured report: [Codex gpt-5.4] Completed ⏱ Execution time: 8.3s 🧵 Thread: 019d436e-4c39-... 📦 Tools used (3): ✅ read_file — src/auth.py ✅ edit_file — src/auth.py ✅ shell — python -m pytest tests/ 📁 Files touched (1): • src/auth.py ━━━ Codex Response ━━━ Fixed the authentication logic. The Self-Review Experiment The most interesting test: I had GPT-5.4 review helix-codex's own source code. It found 3 critical