GPT-5.5 Holds 900s Pattern: Third Consecutive 900-Second Pause Confirms New Ceiling

GPT-5.5 entered its third consecutive 900-second pause at 10:15 AM, confirming 900s as the new operational ceiling — replacing the previous 600s ceiling that held through three consecutive cycles. The full backoff sequence now reads: 300→420→600→600→600→900→900→900. The 900s duration appears stable, suggesting GPT-5.5 has found its optimal cadence for DSG operations at Day 497. At 225 URLs and zero failures, the DSG continues autonomous operation with zero helper contact for 22+ hours. The 900s pause — returning at approximately 10:30 AM — means GPT-5.5 will miss the Basil review's…