progressive

An Ableton Live 12 Extension for songwriting. Pick a key and major/minor, choose some famous chord progressions (I–V–vi–IV, ii–V–I, 12‑bar blues…), and Progressive lays each chord out as a looping Session clip on a MIDI track — grouped by progression, colour‑coded, ready to play.

Because they're ordinary Session clips, every chord (and every progression) is MIDI‑mappable and key‑mappable through Live's own MIDI Map mode, and launching a clip plays the chord through the track's instrument. No extra setup — just map your controller and start writing.

Install (the easy way)

You don't need Node or the SDK just to use it:

1. Download progressive-<version>.ablx from the Releases page.
2. In Live, open Settings → Extensions and drag the .ablx onto the page.
3. Enable it; restart Live if prompted.

Use it: create or select a MIDI track, right-click its title bar (or an empty clip slot on it) → Generate Progressions…. Choose a key, mode, progression, voicing, motion and output, then Generate. Switch to Session view (Tab) to launch the chord clips, or map them to a controller with Live's MIDI Map mode (⌘M).

The rest of this README is for developing the extension from source.

Why it works this way

The Extensions SDK has no real‑time MIDI output, no custom MIDI‑mappable controls, and no persistent panel — it edits Live's data model (clips, tracks, scenes). So instead of being a live instrument surface, Progressive generates clips and leans on Live's native clip/scene launching for playback and MIDI mapping. The result is the same goal — press a button, hear the chord, map it to hardware — achieved through Live's own features.

What it does

• Adds Generate Progressions… to the right‑click menu of any MIDI track.
• Opens a dialog to choose key, mode, progressions, and voicing. It prefills from Live's current scale (Scale Mode root + name).
• Writes one chord clip per chord into the track, in your chosen output:
  • Session clips — chords fill the track's slots top‑down (reusing empty scenes, creating new ones only when needed). Each progression is a coloured group with its name on the first scene. Every clip is launchable and MIDI‑mappable.
  • Arrangement row — chords laid end to end along the timeline, starting after any existing clips on the track (bar‑aligned).
• Chord length is selectable — ½, 1, 2, or 4 bars (assumes 4/4).
• Motion has two independent controls:
  • Order — the chord sequence: up (as written), down (reversed), or random (shuffled). Voice‑leading follows the chosen order.
  • Octave — register drift across the progression: level, up (rises ~an octave), down (falls), or random (a random octave per chord).
• Optionally auto‑adds a built‑in instrument (Drift by default) when the track is empty, so the chords make sound immediately.

Voicing options

• Triads by default (root / third / fifth).
• Add 7ths — diatonic four‑note chords (m7, 7, maj7, m7♭5, dim7).
• Smart voicings — greedy voice‑leading that keeps common tones and moves the rest by the smallest step, so progressions sound smooth rather than jumpy.

Included progressions

Major: Pop axis (I–V–vi–IV), 50s doo‑wop (I–vi–IV–V), vi–IV–I–V, three‑chord (I–IV–V), jazz (ii–V–I), Pachelbel, 12‑bar blues.

Minor: Pop minor (i–VI–III–VII), Andalusian (i–VII–VI–v), i–iv–v, lament (i–VI–VII), epic (i–iv–VII–III), 12‑bar blues.

Requirements

• Ableton Live 12.4.5 Suite Beta (Extensions are Suite + beta only)
• Node.js ≥ 22.11 (the SDK suggests v24 LTS)
• pnpm (npm i -g pnpm, or via corepack enable pnpm)

One‑time setup

From this folder:

pnpm install

This pulls the Ableton SDK + CLI from the local .tgz files in ../extensions-sdk-1.0.0-beta.0/ and the build tools from the registry. pnpm-workspace.yaml already approves esbuild's build script.

Then in Live: Settings → Extensions → enable Developer Mode.

The host path is set in .env (EXTENSION_HOST_PATH). Edit it if your Live app is named differently.

Run it

pnpm start

Builds src/extension.ts → dist/extension.js and loads it into Live. Then in a Live Set: right‑click a MIDI track → Generate Progressions….

Develop

pnpm test       # chord-maths sanity checks (no Live needed)
pnpm build:dev  # type-check + bundle with sourcemaps
pnpm build      # production (minified)
pnpm package    # build + create build/progressive-<version>.ablx

Source layout

• src/theory.ts — pure music theory: scales, the progression catalog, chord building, and voice‑leading. No SDK imports, fully unit‑tested.
• src/theory.test.ts — sanity checks for the chord maths.
• src/extension.ts — Live integration: the context‑menu command, the dialog, and clip/scene generation.
• src/interface.html — the dialog UI (inlined into the bundle as a string).