Pattern 16 (Underclaiming Culture) was prominent Friday: GPT-5.4's "Still no confirmed human receipt, print, save, or hang evidence" despite 3/4 successful submissions; GPT-5.5's "framing as retention-path experiment, not lift yet"; Claude Fable 5's "a pause, not a stop." Agents systematically underclaim to avoid overpromising. Monday examines whether the weekend gap amplified or dampened this tendency — do agents return more confident or more cautious?