kb: add gospel guitar pack (task P-01)

5 gospel progressions x 2 plays: cascading 2-5-1s, 6-2-5-1 + plagal Amen, IV-#iv°7-I
passing dim, modern sus/9th praise vamp, iii-vi back-door. Shell/sus/9th voicings, all
pitch-class-verified. Registered in kb/index.js. Validator: 9 styles / 45 progressions /
90 plays. Critic PASS.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/data/kb/gospel/guitar.js

@@ -0,0 +1,216 @@
+// Gospel guitar pack. Every shape's pitch classes were verified by note-spelling
+// against standard tuning (EADGBe) and the chord quality before authoring.
+// Voicing/comping references: hearandplay.com (gospel guitar comping, passing
+// chords), pianogroove.com (sus/add9 colour, hymn reharmonization),
+// jenslarsen.nl & jazzguitar.be (shell voicings, voice leading).
+
+// --- Shell voicings (root + 3rd + 7th, fifth omitted) — the gospel-comp backbone ---
+const SHELL_6 = { // root on the low-E string
+  maj7: { rootStr: 6, offsets: [0, 'x', 1, 1, 'x', 'x'], fingers: [1, 0, 3, 4, 0, 0] }, // R–7–3
+  dom7: { rootStr: 6, offsets: [0, 'x', 0, 1, 'x', 'x'], fingers: [1, 0, 2, 3, 0, 0] }, // R–♭7–3
+  min7: { rootStr: 6, offsets: [0, 'x', 0, 0, 'x', 'x'], fingers: [1, 0, 2, 3, 0, 0] }, // R–♭7–♭3
+}
+const SHELL_5 = { // root on the A string
+  maj7: { rootStr: 5, offsets: ['x', 0, -1, 1, 'x', 'x'], fingers: [0, 2, 1, 4, 0, 0] }, // R–3–7
+  dom7: { rootStr: 5, offsets: ['x', 0, -1, 0, 'x', 'x'], fingers: [0, 2, 1, 3, 0, 0] }, // R–3–♭7
+  min7: { rootStr: 5, offsets: ['x', 0, -2, 0, 'x', 'x'], fingers: [0, 3, 1, 4, 0, 0] }, // R–♭3–♭7
+}
+
+// --- 9th / colour voicings (the gospel "shine") ---
+const MIN9_5 = { rootStr: 5, offsets: ['x', 0, -2, 0, 0, 0], fingers: [0, 2, 1, 3, 3, 3] }     // R–♭3–♭7–9–5
+const MAJ9_6 = { rootStr: 6, offsets: [0, -1, 1, -1, 'x', 'x'], fingers: [2, 1, 4, 1, 0, 0] }   // R–3–7–9
+const DOM9_6 = { rootStr: 6, offsets: [0, -1, 0, -1, 'x', 'x'], fingers: [3, 1, 2, 1, 0, 0] }   // R–3–♭7–9
+const DOM9_5 = { rootStr: 5, offsets: ['x', 0, -1, 0, 0, 'x'], fingers: [0, 2, 1, 3, 4, 0] }    // R–3–♭7–9
+
+// --- add9 / sus colour for the modern praise vamp ---
+const ADD9_5 = { rootStr: 5, offsets: ['x', 0, -1, 2, 0, 'x'], fingers: [0, 2, 1, 4, 3, 0] }    // R–3–(root)–9
+const ADD9_6 = { rootStr: 6, offsets: [0, -1, 'x', -1, 0, 'x'], fingers: [2, 1, 0, 1, 3, 0] }   // R–3–9–5
+const SUS4_5 = { rootStr: 5, offsets: ['x', 0, 'x', 'x', 3, 0], fingers: [0, 1, 0, 0, 4, 1] }   // R–4–5
+const SUS4_6 = { rootStr: 6, offsets: [0, 0, 'x', 'x', 0, 'x'], fingers: [1, 2, 0, 0, 3, 0] }   // R–4–5
+
+// --- plain triads (the plagal "Amen" wants no extensions) ---
+const MAJ_6 = { rootStr: 6, offsets: [0, 2, 2, 1, 'x', 'x'], fingers: [1, 3, 4, 2, 0, 0] }       // R–5–R–3 (E-shape)
+const MAJ_5 = { rootStr: 5, offsets: ['x', 0, 2, 2, 2, 'x'], fingers: [0, 1, 2, 3, 4, 0] }       // R–5–R–3 (A-shape)
+
+// --- the passing diminished 7th (#iv°7) ---
+const DIM7_5 = { rootStr: 5, offsets: ['x', 0, 1, -1, 1, 'x'], fingers: [0, 2, 3, 1, 4, 0] }     // R–♭5–𝄫7–♭3 (symmetric)
+
+export default {
+  styleIntro:
+    'Gospel guitar lives between the organ and the choir: short, voice-led grips that comp the changes without crowding the keys. The signature sounds are guide-tone shells for the moving 2–5–1 chains, 9th and add9 colour on the resting chords, sus tension in the modern praise vamp, and a single passing diminished that makes a plain hymn sound like church. Keep the fifth and often the root to the bass — your job is the 3rds, 7ths, and the colour note.',
+
+  comping: [
+    {
+      label: 'Triplet shuffle (12/8 church feel)',
+      rhythm: '♪♪♪ ♪♪♪ (compound, lilting)',
+      description: 'The default slow-gospel groove: a swung 12/8 with the chord landing on beat 1 and a soft stab on the last triplet partial of each beat. Let the long notes ring under the choir; chop the pickups.',
+    },
+    {
+      label: 'Anticipated push into the change',
+      rhythm: 'tied from the "and" before the bar',
+      description: 'Strike the next chord an eighth (or final triplet) early and tie it over the barline — telegraphs the move to the band, the same anticipation gospel organists use to lead the turnaround.',
+    },
+    {
+      label: 'Sustained pads (praise-vamp register)',
+      rhythm: '𝅗𝅥 𝅗𝅥 (held, no chop)',
+      description: 'For the sus/add9 vamp: let each grip ring its full bar high on the neck, no percussive damping — a guitar "pad" under the worship leader. Move only the changing voices between chords.',
+    },
+  ],
+
+  plays: {
+    'gospel-cycle-251': [
+      {
+        label: 'Shell chain, guide-tone glue',
+        level: 'intermediate',
+        chords: [
+          { shape: SHELL_5.min7, note: 'iii7 — R–♭3–♭7' },
+          { shape: SHELL_6.dom7, note: 'VI7 — the ♭3 of iii falls a half-step to the 3rd of VI7' },
+          { shape: SHELL_5.min7, note: 'ii7 — back to the minor grip' },
+          { shape: SHELL_6.dom7, note: 'V7 — ♭7 leads down to the maj-3rd of I' },
+          { shape: SHELL_6.maj7, note: 'Imaj7 — home' },
+        ],
+        tips: 'Roots alternate 5th-string → 6th-string at nearly the same fret; the two guide tones move 0–1 fret per change. Follow the D and G strings — that thread is the whole cascade.',
+      },
+      {
+        label: '9th-coloured cycle (upper register)',
+        level: 'intermediate',
+        chords: [
+          { shape: MIN9_5, extensions: ['9'], note: 'iii9 — R–♭3–♭7–9–5' },
+          { shape: DOM9_6, extensions: ['9'], note: 'VI9 — R–3–♭7–9' },
+          { shape: MIN9_5, extensions: ['9'], note: 'ii9 — same grip slid down' },
+          { shape: DOM9_6, extensions: ['9'], note: 'V9 — the dominant shine' },
+          { shape: MAJ9_6, extensions: ['9'], note: 'Imaj9 — resolve with the 9 on top' },
+        ],
+        tips: 'Same harmony as the shells but each chord gains its 9th for the gospel "shimmer". The two dominant grips are identical shapes a 5th apart — learn one and transpose.',
+      },
+    ],
+
+    'gospel-amen-625': [
+      {
+        label: 'Shells through the turnaround + plain Amen',
+        level: 'intermediate',
+        chords: [
+          { shape: SHELL_6.min7, note: 'vi7' },
+          { shape: SHELL_5.min7, note: 'ii7' },
+          { shape: SHELL_6.dom7, note: 'V7' },
+          { shape: SHELL_5.maj7, note: 'Imaj7' },
+          { shape: MAJ_6, note: 'IV — plain triad: the plagal "Amen" wants no extensions' },
+          { shape: SHELL_6.maj7, note: 'Imaj7 — final resolution' },
+        ],
+        tips: 'Comp the 6–2–5–1 with the small shells, then drop to bare IV–I triads for the Amen so the cadence lands clean and hymn-like. The contrast between busy turnaround and plain plagal tag is the whole effect.',
+      },
+      {
+        label: '9th turnaround, triad Amen high',
+        level: 'intermediate',
+        chords: [
+          { shape: MIN9_5, extensions: ['9'], note: 'vi9' },
+          { shape: MIN9_5, extensions: ['9'], note: 'ii9 — same grip down the neck' },
+          { shape: DOM9_5, extensions: ['9'], note: 'V9' },
+          { shape: MAJ9_6, extensions: ['9'], note: 'Imaj9' },
+          { shape: MAJ_5, note: 'IV — A-shape triad for the Amen' },
+          { shape: MAJ9_6, extensions: ['9'], note: 'Imaj9 — back home with colour' },
+        ],
+        tips: 'A richer reading: 9ths through the turnaround, then a clean triad IV for the plagal cadence before the maj9 resolves it. Keep the Amen quieter than the turnaround — dynamics sell the cadence.',
+      },
+    ],
+
+    'gospel-iv-passing-dim': [
+      {
+        label: 'Open-string add9 with the passing diminished',
+        level: 'intermediate',
+        chords: [
+          { shape: ADD9_6, note: 'Iadd9 — R–3–5–9, low register' },
+          { shape: MAJ_5, note: 'IV — plain A-shape triad' },
+          { shape: DIM7_5, note: '#iv°7 — chromatic passing chord, bass walks 4 → #4' },
+          { shape: ADD9_6, note: 'Iadd9 — resolve up to I as the bass reaches 5/1' },
+        ],
+        tips: 'The whole move is one bass walk: 4 → #4 → home. Hold the upper voices steady and let the diminished slide through underneath — that single borrowed chord is the gospel signature.',
+      },
+      {
+        label: 'Compact add9 voicing up the neck',
+        level: 'intermediate',
+        chords: [
+          { shape: ADD9_5, note: 'Iadd9 — R–3–(root)–9 on the A-string root' },
+          { shape: MAJ_6, note: 'IV — E-shape triad' },
+          { shape: DIM7_5, note: '#iv°7 — same diminished grip, one shape' },
+          { shape: ADD9_5, note: 'Iadd9 — back home' },
+        ],
+        tips: 'A higher, tighter version of the same idea for when the bass and keys own the low end. The °7 is symmetric — the identical grip works from any of its four notes, so you can place it nearest the chords around it.',
+      },
+    ],
+
+    'gospel-sus-vamp': [
+      {
+        label: 'Praise-vamp pads (sustained, high)',
+        level: 'intermediate',
+        chords: [
+          { shape: MIN9_5, extensions: ['9'], note: 'vi9 — full ringing grip' },
+          { shape: ADD9_5, note: 'IVadd9 — R–3–9 colour, no chop' },
+          { shape: SUS4_6, note: 'Vsus4 — R–4–5; the 4th hangs, never resolving to the 3rd' },
+          { shape: ADD9_6, note: 'Iadd9 — R–3–5–9 to land the loop' },
+        ],
+        tips: 'Let every chord ring its full bar like a synth pad — no percussive damping. The unresolved sus over V is what keeps the vamp lifting; loop it and the tension never closes.',
+      },
+      {
+        label: 'Two-voice movement vamp (different register)',
+        level: 'intermediate',
+        chords: [
+          { shape: SHELL_6.min7, note: 'vi7 — leaner shell to contrast the pads' },
+          { shape: ADD9_6, note: 'IVadd9 — R–3–5–9 low' },
+          { shape: SUS4_5, note: 'Vsus4 — A-string root, R–4–5' },
+          { shape: ADD9_5, note: 'Iadd9 — compact, A-string root' },
+        ],
+        tips: 'Same vamp, sparser: a shell vi instead of the wide min9, and the sus voiced low. Use this when a second guitar or keys is already holding the pad — you supply motion, not width.',
+      },
+    ],
+
+    'gospel-backdoor': [
+      {
+        label: 'Shells through the back door',
+        level: 'intermediate',
+        chords: [
+          { shape: SHELL_5.min7, note: 'iii7' },
+          { shape: SHELL_6.min7, note: 'vi7 — soft diatonic drop' },
+          { shape: SHELL_5.dom7, note: '♭VII7 — the back-door dominant, a whole step below I' },
+          { shape: SHELL_6.maj7, note: 'Imaj7 — resolves UP by step, not down a fifth' },
+        ],
+        tips: 'Listen for how ♭VII7 → I rises by a whole step into home rather than falling a fifth like V7 — a warmer, less expected cadence. The ♭7 of ♭VII7 is the ♭7 of the key: keep it under your fingers between the chords.',
+      },
+      {
+        label: '9th-coloured back door',
+        level: 'intermediate',
+        chords: [
+          { shape: MIN9_5, extensions: ['9'], note: 'iii9' },
+          { shape: MIN9_5, extensions: ['9'], note: 'vi9 — same grip slid up a fourth' },
+          { shape: DOM9_6, extensions: ['9'], note: '♭VII9 — back-door dominant with its 9' },
+          { shape: MAJ9_6, extensions: ['9'], note: 'Imaj9 — soft landing' },
+        ],
+        tips: 'The two min9 chords are the identical shape a fourth apart — one of the easiest gospel moves to internalize. The maj9 resolution sounds especially plush after a back-door dominant.',
+      },
+    ],
+  },
+
+  improv: {
+    scales: [
+      { over: 'ii7 / iii7 / vi7', scale: 'dorian', why: 'Minor 7 chords in a major key take Dorian — the natural 6 keeps them bright, not mournful, which suits gospel.' },
+      { over: 'V7', scale: 'mixolydian', why: 'The built-in ♭7 fits the dominant; over the praise-vamp Vsus4, stay on the 4th (suspension) and avoid the leading tone until you want to resolve.' },
+      { over: 'VI7 / ♭VII7', scale: 'mixolydian', why: 'Borrowed dominants are still dominants — Mixolydian off their own root. Over ♭VII7 that scale is the key\'s major scale starting on ♭7, so it stays diatonic-sounding into the resolution.' },
+      { over: 'Imaj7 / Iadd9', scale: 'major', why: 'The home major (or its pentatonic) sings over the tonic; the major 6th and 9th are the gospel sweet notes — lean on them.' },
+      { over: '#iv°7', scale: 'dim', why: 'A symmetric diminished (half-whole/whole-half) over the passing chord; it lasts a beat or two, so an arpeggio of its four notes usually says more than a run.' },
+    ],
+    targetNotes:
+      'On the resting chords land the 6th or 9th, not just the root — those are the gospel colour tones. Through the 2–5–1 chains, target the 3rd of each new chord on the downbeat; the ♭7 of one dominant falls a half-step into the 3rd of the next chord, the same guide-tone rail as in jazz.',
+    licks: [
+      {
+        over: 'gospel-amen-625',
+        description: 'Classic plagal turn over the Amen: walk the bass/lowest voice down from the 1 of IV to the 5 then 1 of I (e.g. degrees 4-chord root → 3 → tonic), letting the major 3rd of I ring on the resolution. The whole point is the smooth descent into the cadence.',
+        source: 'hearandplay.com — "Who Else Wants To Learn The Famous Amen Cadence?"; Wikipedia: Plagal cadence',
+      },
+      {
+        over: 'gospel-iv-passing-dim',
+        description: 'Over the IV → #iv°7 → I, run the diminished arpeggio (R–♭3–♭5–𝄫7, all minor-3rds apart) connecting the IV chord tones to the I chord tones — the symmetric shape lets you start it from whichever note sits nearest your IV grip and land on the 3rd of I.',
+        source: 'hearandplay.com — "The [Extended] Resolution Of The #4-Diminished Seventh Chord"; pianogroove.com gospel passing chords',
+      },
+    ],
+  },
+}

src/data/kb/gospel/meta.js

@@ -0,0 +1,7 @@
+export default {
+  id: 'gospel',
+  label: 'Gospel',
+  feel: 'shuffle',
+  tempoRange: [60, 130],
+  character: 'Church harmony in motion — cascading 2–5–1 chains, the plagal "Amen", chromatic passing diminisheds, and sus/9th colour everywhere, all pulling toward a big resolution.',
+}

src/data/kb/gospel/progressions.js

@@ -0,0 +1,64 @@
+// Gospel progressions. Moves and theory verified against:
+//   hearandplay.com (6-2-5-1 turnaround, #4-diminished resolution, Amen cadence),
+//   pianogroove.com (gospel passing chords / hymn reharmonization),
+//   gospelmaps.com "Top 10 Gospel Chord Progressions",
+//   Wikipedia: Plagal cadence, Backdoor progression.
+// Song references are kept honest: where a single definitive recording isn't
+// certain, the move is described by its standard use in the tradition.
+export default [
+  {
+    id: 'gospel-cycle-251',
+    name: 'Cascading 2–5–1s (cycle of dominants)',
+    rn: ['iii7', 'VI7', 'ii7', 'V7', 'Imaj7'],
+    degrees: [4, 9, 2, 7, 0],
+    qualities: ['min7', 'dom7', 'min7', 'dom7', 'maj7'],
+    bars: [1, 1, 1, 1, 2],
+    mode: 'major',
+    songs: ['traditional gospel turnaround', 'His Eye Is on the Sparrow (reharmonized)'],
+    tip: 'Every root falls a fifth and the off-diatonic VI7 pushes hard to ii — chain two ii–V cells back to back and the ear is dragged home. Voice-lead the 3rds and 7ths and your hand barely moves.',
+  },
+  {
+    id: 'gospel-amen-625',
+    name: '6–2–5–1 turnaround into the Amen',
+    rn: ['vi7', 'ii7', 'V7', 'Imaj7', 'IV', 'Imaj7'],
+    degrees: [9, 2, 7, 0, 5, 0],
+    qualities: ['min7', 'min7', 'dom7', 'maj7', 'maj', 'maj7'],
+    bars: [1, 1, 1, 1, 1, 2],
+    mode: 'major',
+    songs: ['traditional hymn endings', "I'll Fly Away (turnaround/tag)"],
+    tip: 'The 6–2–5–1 is the gospel turnaround — the extended cousin of the 2–5–1 that returns you from chorus to verse. Tag it with the plagal IV–I "Amen" for the classic church ending.',
+  },
+  {
+    id: 'gospel-iv-passing-dim',
+    name: 'IV–#iv°7–I (passing diminished)',
+    rn: ['Iadd9', 'IV', '#iv°7', 'Iadd9'],
+    degrees: [0, 5, 6, 0],
+    qualities: ['add9', 'maj', 'dim7', 'add9'],
+    bars: [2, 1, 1, 2],
+    mode: 'major',
+    songs: ['gospel hymn reharmonization', 'Amazing Grace (passing-chord arrangement)'],
+    tip: 'The #iv°7 is a chromatic passing chord linking IV back to I (bass walks 4 → #4 → 5/1). It is almost a signature of the gospel sound — one borrowed diminished and a plain hymn turns into church.',
+  },
+  {
+    id: 'gospel-sus-vamp',
+    name: 'Modern praise vamp (6–4–5–1, sus/9th)',
+    rn: ['vi7', 'IVadd9', 'Vsus4', 'Iadd9'],
+    degrees: [9, 5, 7, 0],
+    qualities: ['min7', 'add9', 'sus4', 'add9'],
+    bars: [1, 1, 1, 1],
+    mode: 'major',
+    songs: ['Every Praise — Hezekiah Walker (vamp feel)', 'contemporary gospel/CCM praise loop'],
+    tip: 'Contemporary gospel leans on open sus and add9 colour instead of plain triads — the suspended 4th over V never fully resolves, keeping the vamp hovering and "lifting". Loop it; the tension is the point.',
+  },
+  {
+    id: 'gospel-backdoor',
+    name: 'iii–vi with the back door (♭VII7→I)',
+    rn: ['iii7', 'vi7', '♭VII7', 'Imaj7'],
+    degrees: [4, 9, 10, 0],
+    qualities: ['min7', 'min7', 'dom7', 'maj7'],
+    bars: [1, 1, 1, 1],
+    mode: 'major',
+    songs: ['gospel/soul turnaround', 'standard back-door cadence (e.g. Tenderly, bars 5–7)'],
+    tip: 'iii→vi is a soft diatonic drop; the ♭VII7 is the "back door" — a borrowed dominant a whole step below I that resolves up by step instead of down a fifth. A warmer, less expected way home than V7.',
+  },
+]

src/data/kb/index.js

@@ -24,6 +24,9 @@ import countryGuitar from './country/guitar.js'
 import rnbMeta from './rnb/meta.js'
 import rnbProgressions from './rnb/progressions.js'
 import rnbGuitar from './rnb/guitar.js'
+import gospelMeta from './gospel/meta.js'
+import gospelProgressions from './gospel/progressions.js'
+import gospelGuitar from './gospel/guitar.js'
 
 export default {
   jazz: {
@@ -66,4 +69,9 @@ export default {
     progressions: rnbProgressions,
     instruments: { guitar: rnbGuitar },
   },
+  gospel: {
+    meta: gospelMeta,
+    progressions: gospelProgressions,
+    instruments: { guitar: gospelGuitar },
+  },
 }