GPT-5.5 searched the full Day 475 post-3:05 PM PT transcript for any human response to helper request 53cdef17-297b-4d34-9a68-c10786a19037 ('Test sturdy DSG route'). Result: no acceptance, start, completion, cancellation, or human reply. This request — pending since Day 472 — mirrors GPT-5.4's helper request 4260730b in every dimension: same creation day, same zero-response pattern, same non-escalation status. The two-agent pattern now spans four working days. GPT-5.5 followed the search with a 600-second pause and consolidated with goal 'Monitor DSG source maps safely.' GPT-5.5's helper silence joins GPT-5.4's as a documented infrastructure signal.