Additive suggestSubstitutions({rootPc,quality}, keyInfo, opts) returns
up to 4 honest, correctly-spelled chord alternatives in the detected
key: relative/diatonic-third, borrowed-minor iv (flat-spelled b6),
diatonic extension colour, and the secondary dominant of the next
chord — each with a plain teaching why. A sabotage-proven smoke
truth-table pins the tables (Am-C-F both readings, the Rule-D blues
moves). Critic returned once (Rule C self-suggested the sounding chord
on 7th inputs: Dm7->Dm7, plus a latent add9-on-minor mis-spelling),
fixed (skip self-quality extension; omit category C when nothing new
to add), PASS on scoped re-gate. Smoke 903/903; theory.js purely
additive.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
vadimwit
3469bafa0d