One authoritative engine, two seat-locked MCP servers, three best-of-threes, and a 3-millisecond whodunit The matches are real: Codex CLI ( gpt-5.6-sol ) against Claude Code (Claude Opus 5), both playing through the same rules engine. Every number below was recomputed from the raw run.json and both session logs, and every game replays deterministically from its seed. Quotes from the agents are verbatim from decision-time records. None of this is a general model ranking. I wired Code...