Review follow-up on 43215c7. Both findings were right, and the second falsified a
comment I wrote in that very commit.
1. Region staff bands were still identified by glyph `members`. vertical_raw
measured content over all primitives but decided WHICH staff bands belong to a
region by glyph membership -- reintroducing the assumption the change exists to
shed. A staff band is allowed to own no glyphs: to_constrained emits one per
staff of the region regardless, and a percussion-clef staff (no bundled glyph,
so it engraves to a traced anchor stroke) with no notes owns only staff-line
strokes. Membership now comes from content presence in one of the region's
systems, which identifies the band exactly -- a staff band is per-(staff,
region), so its content can land nowhere else.
2. Only the first realizing system was measured, justified by a comment claiming
rigid system translation makes every realization agree. The inter-staff solve
had just falsified that: it sizes each system's gaps from that system's own
content. req:qmc:vertical now counts ONE UNIT PER REALIZATION, matching how
realized inter-system gaps were already counted. That is a contributing-unit
change, so unlike 43215c7's clarification the catalog moves: QMC 0.2.0 -> 0.3.0
(the P12-I12 precedent). Raw formula, anchor, orientation, thresholds unchanged.
Two new fixtures, because an unexercised fix is what I criticised last round:
percussion_placeholder_staff (a valid, invariant-clean score whose lower band owns
zero glyphs and six strokes) and two_staff_wrapping_pressure (one region, two
systems, staff-line gap 15.93 where it collides and 7.87 where it is slack). Both
mutation-verified: the members filter scores 4.8e-7, first-system-only scores
1.3e-7 -- each ~0 where the corrected axis reports real deviation.
What the per-realization count exposes is not comfortable, and is recorded rather
than smoothed over: two_staff_wrapping_pressure now scores 0.739. Its pressured
system solves to the declared gap exactly; its slack system sits at ~5 staff
spaces against a preferred 2.0. The axis is symmetric -- a gap wider than
preferred is sprawl exactly as a narrower one is crowding -- and this solve only
expands, never compresses. The deferral "compressing an OVER-wide fixed gap toward
preferred ... rarely wanted" is promoted to measurably wrong. Named, not fixed:
compression is a layout change (golden churn, ENGRAVER_VERSION move), not a
measurement one.
Adjacent finding, parked: Staff::default_clef is never consulted -- to_constrained
takes the active clef from the instance's clef_sequence and falls back to
Clef::default() (treble), so a staff declaring its clef only on Staff engraves as
treble. Verified (no layout-ir consumer reads the field). Filed in layout-ir
DECISIONS with the ConstrainedLayoutIR listing gap, pending a >=3-candidate batch.
Measurement-only: no layout change, ENGRAVER_VERSION stays 11, zero golden churn.
Gate green; QMC PDF rebuilds clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Levi Neuwirth
5b016f33b7