44f45d16a9
qual+repairs are the pipeline's largest cost pool (51M of 164.5M real tokens, 31%, in the 206-run corpus), with opus weighing ~5x on the quota side. The opus pin's own rationale (consequence-of-a-miss, agent-template § model) scales with diff size — so the tier now does too: the spec-reviewer, which runs before quality, reads the diff itself and is independent of the implementer, reports diff_magnitude (git diff HEAD --shortstat) and touches_contract; <=25 changed lines and no contract-referenced path -> sonnet/high, anything larger, contract-touching, or unmeasured -> opus/xhigh (fail conservative). The independent end-verify/mini-verify suite gate is the deterministic backstop that makes the lower tier defensible; the chosen tier is logged per task (qual_tier) in the end-report. Sampling phase per the issue's acceptance: the first ~10 real small-diff iterations get a one-off opus second review; important+ divergences are recorded on the issue before the threshold counts as proven. closes #30