An adversarial review of the slur-quality tranche found a real interaction bug
between curve splitting (commit 5869691) and slur_shape measurement (7d61271):
slur_shape_raw iterated cast.curves — the per-system SUB-CUBICS of a
break-spanning slur — and measured each fragment as a unit. A slur that is
ideally shaped as a whole (ρ ≈ 0.16, in-band) splits into sub-arcs whose
diagonal chords each read flatter (ρ below 0.08), so the whole slur earned a
spurious "too flat" penalty (confirmed ~0.088) and was double-counted —
contradicting the catalog's "a tier that draws the ideal shallow arc measures 0"
property.
Fix: measure the WHOLE slur curves of the constrained input.curves (one unit per
drawn slur — the engraver's arc-proportion decision), not the cast fragments.
Casting's horizontal re-spacing and system-splitting are spacing/rendering
concerns, not shape ones. The Quality Metric Catalog contributing-units
definition is clarified: the unit is the whole slur, measured once even when
split across a break.
Regression: a break-spanning in-band slur splits (≥2 segments) yet measures 0.
Still measurement-only (no ENGRAVER_VERSION bump, no golden churn, RS suite
unaffected). 936 tests, conformance 8/8.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Levi Neuwirth
e6308371d5