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Extend the opt2 R-sensitivity test to assert the opt3/opt2 dispatch ratio increases as R decreases (4.20x -> 5.22x -> 5.45x at R=0.25/0.0625/0.03125) — the cost is FIXED-dominated (command-count-driven), per ADR-0064 Test #9. Test-only; no production change (the P0 cost model + P2 recipe already make the ratio measurable). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>