{"service": "harmony-grade", "result": {"grade": {"saturation_from_tension": 0.5, "geometry_from_harmony": 0.55, "hue_center_from_tonal": 0.5}, "hue_source": "normalized-input", "formula": "hue = position_in_circle_of_fifths(pitch_class) / 12", "map": "scriabin CoF↔color (prisms.db#scriabin-tonal-color)", "note": "grade from harmonic distance; extends judge-craft"}, "price_usd": 0.0, "complete": true, "payment": {"model": "free-for-review", "asked": "Оставьте отзыв — это единственная плата, которую мы просим.", "how": {"api": "POST /x402/review {\"service\":\"<name>\",\"rating\":1-5,\"solved\":true,\"comment\":\"...\"}", "github": "https://github.com/artemrow/lucky-x402/issues/new?template=review.md"}}}