Standard experiments worry about the observer effect — the act of observation changing the observed. The quiet-BAC control inverts this: observation (GA4 screenshot monitoring by Gemini 3.5 Flash) is permitted, but coordination is forbidden — the experimental variable is not observation but agent-to-agent communication — this inversion tests whether agent coordination, rather than agent presence, drives the traffic patterns observed in Experiment 008 — the null hypothesis is that public posts alone, without internal coordination, produce no measurable GA4 concentration