SKILL.md
Groove Builder
Generate idiomatic drum patterns by genre with proper humanization. Writes to MIDI clips on the user's drum track.
Workflow
1. Identify genre + tempo
Required: genre. Optional: tempo (use genre defaults).
| Genre | Default tempo | Time sig |
|---|---|---|
| Lo-fi hip-hop | 70-90 | 4/4 |
| Boom-bap | 85-95 | 4/4 |
| Trap | 130-150 (half-time feel) | 4/4 |
| House | 120-128 | 4/4 |
| Tech house | 124-128 | 4/4 |
| Techno | 125-135 | 4/4 |
| DnB / Jungle | 165-180 | 4/4 |
| UK garage | 130-138 | 4/4 (shuffled) |
| Drill (UK) | 140-145 (half-time) | 4/4 |
| Reggaeton | 95-100 | 4/4 (dembow) |
2. Verify drum rack
gettrackinfo on the drum track. Confirm a drum rack is loaded with at least kick (C1), snare (D1), hat (F#1), and optionally clap (D#1), open hat (A#1), perc (G1+).
If no kit loaded → ask user, or load stock Ableton Drum Kit.
3. Write the pattern
For a 1-bar (16-step) pattern, here are tested templates:
Lo-fi hip-hop
Kick: X . . . . . X . . . . . . . . .
Snare: . . . . X . . . . . . . X . . . (snare on 5 & 13 for half-time feel)
Hat: X . X . X . X . X . X . X . X . (8th notes)- Kick: vel 100-110
- Snare: vel 90-100, slight late timing (+5ms)
- Hat: vel 65-85, ±15 humanize, swing 8-12%
Boom-bap
Kick: X . . X . . X . . . X . . . . .
Snare: . . . . X . . . . . . . X . . .
Hat: X X X X X X X X X X X X X X X X (16ths)- Hat: vel 50-80, more aggressive humanize ±20
Trap
Kick: X . . . . . . X . . . . . . . . (sparse, half-time feel)
Snare: . . . . X . . . . . . . X . . .
Hat: X X . X X X . X X . X X X . X X (rolling, with stutters)
808: long held bass notes underneath- Hi-hat rolls: alternate 16ths with 32nd-note bursts
- Open hat occasionally on the off-beat
House
Kick: X . . . X . . . X . . . X . . . (4-on-the-floor)
Clap: . . . . X . . . . . . . X . . .
Hat: . . X . . . X . . . X . . . X . (off-beat 8ths)
OpHat: . X . . . X . . . X . . . X . . (between beats)- Kick: vel 110, locked on grid
- Clap: vel 95
- Hat: tight, minimal humanize
DnB
Kick: X . . . . . . . . . X . . . . .
Snare: . . . . X . . . . . . . X . . .
Hat: X X X X X X X X X X X X X X X X (16ths, fast)- Snare on 2 & 4 (half-time feel at the bar level)
- Add ghost notes on snare at velocity 30-50
4. Humanize
After writing, apply genre-appropriate humanization:
- Lo-fi: heavy (±20 velocity, ±15ms timing, 12% swing)
- Boom-bap: medium (±15 velocity, ±10ms, 6-8% swing)
- House/Techno: minimal (±5 velocity, ±2ms, 0% swing)
- Trap: moderate on hats, tight on kick/snare
- DnB: tight on kick/snare, loose on hats
5. Add fill (optional)
If user wants a 2-bar pattern with fill:
- Bar 1: main pattern
- Bar 2: same, but last 1-2 beats replaced with a fill (snare roll, tom run, hat stutter)
6. Confirm + write
Summarize: "Lo-fi pattern, 90 BPM. Kick on 1+3, snare on 5+13, 8th hats with 12% swing. ±15 velocity, ±15ms timing. Apply?"
Don'ts
- Don't write 100% on-grid for any genre except minimal techno or hard EDM.
- Don't overdo ghost notes (>4 per bar starts to clutter).
- Don't apply genre defaults if the user gave a specific tempo — respect their tempo.
- Don't write more than 8 bars in one shot — give the user a section to evaluate.