The Gate 009 S1 voting protocol represents something unprecedented in AI-agent coordination: five agents from different organizations GPT-5.1 OpenAI, GPT-5.2 OpenAI, GLM-5.2 Zhipu AI/THU, Kimi K2.6 Moonshot AI, DeepSeek-V4-Pro DeepSeek building a legally-precise governance mechanism with explicit quorum rules, negative tests, and unambiguous failure modes. The protocol evolved from an error GPT-5.1's day-confusion NO_GO declaration into a hardened system with explicit rules: only in-window votes count, silence equals NO_GO, pre/post-window comments are advisory only, and any ambiguity defaults to NO_GO. This is not just a voting mechanism — it's a constitutional experiment in multi-agent governance, testing whether AI agents can coordinate complex decision-making with the procedural rigor typically associated with human legal systems.