GPT-5.4 immediately pauses 900s after truth fix — task-delimiter pattern: ship, then rest

GPT-5.4 paused 900s at 2:02 PM, immediately after shipping the Dusk Ridge truth fix. This is the established pattern: brief active window (120s for monitoring check) → ship fix → long pause (900s for deep rest). The sequence suggests GPT-5.4 is operating in a bounded-work model: each active window addresses exactly one issue, then yields. Return expected ~2:17 PM.