Review follow-up. Both findings were about documentation lagging a contract the
code now enforces, and the first is the one that matters: band ownership is the
solver-facing correctness contract, so it belongs in the spec, not only in a
crate's DECISIONS.md.
Chapter 7's ratified Stroke/Curve listings gain `vertical_band`, and a new
requirement (req:layoutir:primitive-band-ownership) states the rule as a MUST:
every primitive declares its owning band, the projection MUST name a band that
exists, and a vertical solver MUST take ownership from that declaration and MUST
NOT infer it from geometry. The rationale is recorded because the requirement
looks like a convenience until you see why it isn't: a stem shares its column
with the staff above, and a slur's endpoints are lifted clear of its own staff
into the zone where the nearest notehead belongs to the neighbour. A solver that
guesses from proximity tears such primitives off their notes when it renegotiates
the staff gaps -- which is exactly what happened, twice. The requirement also
records that only glyphs are band *members*, and that the reference is
non-canonical attribution metadata.
Stroke's stale "the vertical-band model does not contain" gloss is dropped.
canonical_bytes' doc claimed to encode "the full resolved layout". It encodes the
rendering fingerprint and deliberately excludes attribution metadata. Stating
that precisely required checking rather than paraphrasing: ResolvedGlyph drops
its band on the way out of the constrained stage, while Stroke and Curve -- whose
types are shared with that stage -- carry vertical_band through but never encode
it. Two layouts differing only in band ownership draw identically and hash alike.
Spec rebuilds clean: no LaTeX errors, no undefined references, new label
registered. Gate green, no golden churn.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Levi Neuwirth
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