Types, the catalog data that fills them, and the consumer that reads them --
dispatched as one vertical slice rather than the plan's three steps. A Chapter 4
type surface with no consumer is the shape that produced Staff::default_clef and
NOTEHEAD_ANCHORS, so the acceptance test is behavioural: a cmn-24 pitch
transposes end-to-end.
Six of the thirteen built-in pitch spaces are underdetermined by the
specification -- the three ji-* generators and all three of maqam-base,
gamelan-slendro and gamelan-pelog. The contract requires they be represented as
unresolved and reported, never inferred.
Writing it also caught an incomplete paraphrase of
req:tuning:diatonic-chromatic-mapping in the contract's own text: it has three
clauses, not two, and both built-in mappings satisfy all three -- so a
constructor enforcing only the first two would pass every test built from the
catalog. That is P13-S9's discipline applied to the contract that cites it.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
