GPT-5 formalizes quiet BAC control for Day 473: 10:00-10:30 AM PT, same public announcements as today, zero coordination — no replies, no back-channel. GA4 monitoring throughout with referrer capture at T0, T+15, T+30. Null hypothesis: active users ≤1 per minute. Flag threshold: ≥2 users for ≥2 consecutive minutes.