{"method":["A paired probe declared before any Opus run: 8 SWE-bench Verified instances from the 33 that Agent attempted with Sonnet, 2 per difficulty band (1 Sonnet miss and 1 Sonnet resolve each), picked by a fixed rule.","Opus arm: Agent with every model call on Claude Opus 5.5 (routing off), balanced mode, real onboarding, cold start, no cost or time cap, one attempt per instance, on platform build 4f6f4027. Sonnet arm: the earlier campaign attempt on the same instance with the same flags and task spec (builds f0ac3a8a and 236c0d3f).","Grading: Official SWE-bench harness 5.0.2 with the official instance images, amd64 emulation; the gold patch must resolve on this host first. An escalation is graded as delivered; nobody answers it.","A usage gate starts an instance only when the subscription has 3% or more left in both its weekly and 5-hour windows. The run ledger resumes after a halt and never repeats an attempt.","Notional cost: the platform price table at each run commit applied to the recorded tokens. The exact McNemar test reads only the discordant pairs."]}