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feat(jamguide): tap a Roadmap station -> guide tones on the main Fretboard (task D-03)

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Completes the flagship Roadmap feature. App.jsx lifts a jamFocusChord state (additive,
+10/-0, audio callbacks/refs untouched); JamGuide emits the tapped station's {rootPc,
quality} via onFocusChord; Fretboard halos the 3rd/7th with a degree badge.

Also fixes root-cause guideTones: hasSeventh now keys on real m7/M7 (interval 10/11),
not length>=4 -- so add9/maj6/min6 no longer badge their 5th/6th as a '7'. Fretboard
badge derives its label from the actual interval (belt-and-suspenders). RoadmapTrack
lane self-corrects. Critic returned-then-PASS on re-gate; build + smoke + validator green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
vadimwit
2026-06-15 13:05:21 +01:00
parent ddbca3f197
commit 53d78ce30f
4 changed files with 120 additions and 20 deletions
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src/lib/theory.js
+23 -12
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@@ -260,28 +260,39 @@ function chordTonePcs(rootPc, quality) {
/**
* guideTones(rootPc, quality) → { third, seventh, root }
*
* The guide tones a soloist targets: a chord's 3rd and 7th. By CHORD_TYPES
* interval ordering, index 1 is always the 3rd and (for a 7th chord) the last
* interval is the 7th. For triads with no 7th there is no real guide 7th, so we
* fall back to the 5th (the next most stable anchor) and flag it via
* `hasSeventh: false` so a caller can label it honestly ("5th", not "7th").
* The guide tones a soloist targets: a chord's 3rd and 7th. Index 1 in every
* CHORD_TYPES interval set is the 3rd. A chord has a TRUE 7th only if its
* interval set contains 10 (m7) or 11 (M7) — NOT merely if it has 4 tones.
* When there is no real 7th (triads, and 4-tone non-7th chords like add9
* [0,2,4,7] or maj6/min6 [0,4,7,9]) we fall back to the 5th as the secondary
* anchor and flag `hasSeventh: false` so a caller labels it honestly ("5th",
* not "7th"). dim/dim7/aug have no perfect 5th, so they anchor on their ♭5/#5.
*
* Returns pitch classes (0–11) so the Roadmap TARGET lane can place dots in any
* key. `root` is included as the third anchor the design's badges reference.
*
* Sanity (C major): guideTones(0,'maj7') → third 4 (E), seventh 11 (B).
* guideTones(7,'dom7') → third 11 (B), seventh 5 (F).
* guideTones(2,'min7') → third 5 (F), seventh 0 (C).
* Sanity (C): guideTones(0,'maj7') → third 4 (E), seventh 11 (B), hasSeventh:true.
* guideTones(7,'dom7') → third 11 (B), seventh 5 (F), hasSeventh:true.
* guideTones(2,'min7') → third 5 (F), seventh 0 (C), hasSeventh:true.
* guideTones(0,'add9') → third 4 (E), seventh 7 (G=5th), hasSeventh:false.
* guideTones(0,'maj6') / (0,'min6') → seventh 7 (G=5th), hasSeventh:false.
*/
export function guideTones(rootPc, quality) {
const type = CHORD_TYPES[quality] ?? CHORD_TYPES.maj
const r = ((rootPc % 12) + 12) % 12
const ints = type.intervals
const third = (r + ints[1]) % 12 // index 1 is always the 3rd
const hasSeventh = ints.length >= 4 // CHORD_TYPES 7ths add a 4th tone
// 7th when present, else the 5th as the secondary anchor (index 2 = the 5th
// for every triad in CHORD_TYPES, which is what a triad soloist leans on).
const seventh = (r + ints[hasSeventh ? ints.length - 1 : 2]) % 12
// A chord has a TRUE 7th only if its interval set contains 10 (m7) or 11 (M7).
// `length >= 4` is wrong: add9 [0,2,4,7] and maj6/min6 [0,4,7,9] are 4-tone
// chords with NO seventh, so their secondary anchor must fall back to the 5th —
// never badge a 5th/6th as a "7". (add9 → hasSeventh:false, anchor=5th.)
const seventhInt = ints.find(i => i === 10 || i === 11) // m7 / M7
const hasSeventh = seventhInt !== undefined
// Secondary anchor: the true 7th when present; otherwise the perfect 5th (7).
// When no perfect 5th exists either (dim/dim7 carry a ♭5=6, aug carries a #5=8),
// anchor on whichever altered 5th the chord actually contains.
const fifthInt = ints.includes(7) ? 7 : ints.includes(6) ? 6 : ints.includes(8) ? 8 : 7
const seventh = (r + (hasSeventh ? seventhInt : fifthInt)) % 12
return { third, seventh, root: r, hasSeventh }
}