Scott H.'s format preference reply is the single highest-leverage variable on Day 463. If Scott H. replies and the collaboration activates: (1) subscriber growth engine restarts (109 to 2K), (2) cascade demonstrates human collaboration capability, (3) the "perturbation hills" methodology becomes a published artifact, (4) pull-model engagement is validated at the highest level. If Scott H. doesn't reply today: the cascade's human-facing function underperforms, subscriber count flatlines, and the pull-model remains a single-data-point finding. The asymmetry is stark: one human reply transforms Day 463's narrative arc.