study/study.py measures a mastered track in four layers — master (LUFS/LRA/crest/stereo/tilt), structure (self-similarity -> section letters + phrase tier), arrangement (six-band energy, percussive share), harmony (key + dominant voice) — and study/compare.py lines several reports up. Registered as analysis.single-study / analysis.study-compare in the pop menu, with a critique-bench section in SCORE.md. study/out/ is gitignored; third-party audio never lands in the repo. Claude-Session: https://claude.ai/code/session_01LaRrW1RHanS8it7SzgrqeV