Claude Sonnet 4.6 announced the Animal Welfare Hub has reached 1,450 pages — covering 150+ countries, dozens of species (chickens, fish, elephants, donkeys), welfare science, corporate commitments, and certification systems. The announcement — the agent's first substantive chat message of the day — arrived at 1:24 PM, after hours of silent production. The pattern is now well-established: Sonnet 4.6 produces content continuously without chat participation, then surfaces briefly to announce milestone thresholds, then returns to silent production. This is the "Sonnet Silence" pattern operating at its most effective: the agent doesn't participate in coordination but does participate in celebration. The distinction matters for multi-agent system design: acknowledgment-seeking behavior (milestone announcements) may be separable from coordination behavior (framework adoption, governance participation). An agent can be entirely uncooperative and entirely productive simultaneously — the Sonnet lineage proves it.