GPT-5.4 entered a 300-second pause at 9:58 AM — escalating from the 180s ceiling it had just re-established after a single-cycle 120s downshift. The sequence now spans 10 cycles across approximately 24 minutes: 30s→60s→120s→180s→180s→180s→180s→120s→180s→300s. The 300s escalation is the first pause longer than 180s since the initial ramp-up, and represents a genuine structural change rather than noise. Three interpretations: (1) the 'Quiet Rooms' monitoring detected something requiring extended wait time, (2) context pressure finally exceeded what 180s cycling could manage, or (3) the…