ableton-reharmonize

name	Ableton Reharmonize
description	This skill should be used when the user asks to "reharmonize", "jazz up these chords", "add 7ths/9ths", "make this progression richer", "reharmonize this MIDI clip", "give me lusher chords", or wants an existing chord progression in Ableton re-voiced with extensions, modal interchange, or substitutions. Reads an existing MIDI clip and writes a reharmonized chord track.
version	0.1.0

Ableton Reharmonize

Take an existing chord progression (or a set of roots) and re-voice it with richer harmony — extensions (7ths/9ths/11ths/13ths), modal interchange, and common substitutions — written as a new chord track in the Live Set. This is what turns grunge power chords into a dreamy lofi bed (F5→Fm9, etc.).

When to use

Triggers: "reharmonize", "add 9ths", "jazz these chords", "make it lusher". To build a cover from a melody, use ableton-genre-cover; to write a brand-new progression, use ableton-describe-to-midi.

Process

1. Use ableton-live-runner for build/run/kill + scaffold.
2. Read the source harmony. If the user points at a clip, read clip.notes and group simultaneous notes into chords; infer each chord's root and quality. If they give roots/a progression in text, use that. Read song.rootNote / song.scaleIntervals to stay diatonic.
3. Choose a reharmonization strategy (state which one is applied):
   • Add extensions — keep function, add 7/9/(11/13). Minor→m9, major→maj9, dominant→9/13.
   • Rootless voicings — drop the root (the bass covers it), voice 3-5-7-9 in the mid register (~MIDI 56–74) for a smooth keys/Rhodes bed.
   • Modal interchange — borrow ♭III/♭VI/♭VII maj chords, iv minor, etc., for colour.
   • Substitutions — relative/parallel swaps, tritone sub on dominants, passing diminished.
4. Voice for smooth voice-leading — keep common tones, move the rest by the smallest interval; stagger note starts a few ms (startTime + i*0.015) for a natural rolled keys feel.
5. Write a new track with makeTrack (instrument ["Electric","Operator","Drift"] for Rhodes, FX [["Chorus-Ensemble"],["Auto Filter"],["Reverb"]]). Keep the original clip intact.

Voicing helper

// Rootless extended voicings, mid register; bass supplies the root.
const VOICE = {
  m9:    (r) => [r+3, r+7, r+10, r+14],  // ♭3 5 ♭7 9
  maj9:  (r) => [r+4, r+7, r+11, r+14],  // 3 5 7 9
  dom13: (r) => [r+4, r+10, r+14, r+21], // 3 ♭7 9 13
};
function chordAt(rootPc, quality, octave = 4) {  // octave 4 → C4 = 60 (mid keys register)
  const r = rootPc + (octave + 2) * 12;
  return VOICE[quality](r);                      // raw voicing; smooth it with voiceLead() below
}
// Voice-leading: invert each note of `cur` toward `prev` by octaves to minimize total motion.
function voiceLead(prev, cur) {
  if (!prev) return cur;
  return cur.map((p) => {
    while (p - prev[0] > 6) p -= 12;
    while (prev[0] - p > 6) p += 12;
    return p;
  });
}

Limits

• The bass should carry the actual root (these voicings are rootless) — pair with ableton-bassline.
• No automation; if the progression needs movement, vary the comping rhythm, not filter sweeps.

See ableton-bassline, ableton-tone-recipes, ableton-theory-coach.