strudelton

Author Strudel patterns and bake them into Ableton Live MIDI clips — as a Live Extension (Extensions SDK, Live 12.4.5+ Suite beta). A built-in CodeMirror editor with a live piano-roll preview turns a Strudel pattern into notes in a clip: melodies, drums, scales, velocity, and per-note probability that re-rolls every loop.

Status: a working probe (see PROPOSAL.md for the original brief and FINDINGS.md for what it taught us). Bakes in Live 12.4.5 beta; rearchitected to run sandbox-native (no temp files / no child process) so it targets the installed/managed host, not just Developer Mode.

What it does

• Right-click a Session clip slot → "Strudel: Edit & bake…" — opens the editor; write a pattern, set how many bars to bake, hit Bake. The pattern's notes land in a fresh looping MIDI clip.
• Right-click a MIDI clip → "Strudel: Edit & bake…" — re-open that clip's pattern and re-bake.
• Live preview in the editor: a piano-roll of exactly what will bake, transpile errors inline, and a flag for sound-only controls that get dropped (speed, lpf, …).
• Built-in cheat sheet (the ? cheatsheet button): what bakes — scales, chords, arps, velocity/probability, drums — plus the Strudel-vs-Ableton octave gotcha and what's ignored.

Supported in patterns

• Full Strudel core + mini-notation, scales/keys/chords (@strudel/tonal), drums (s("bd sd hh") → Drum Rack), velocity (.velocity()/.gain()), and probability (.prob()/.chance() → Live re-rolls each loop).
• Chords as stacks (note("c,e,g")) or voiced symbols (chord("Cm7").voicing()); arps via numeric indices on a voiced chord (chord("C").voicing().arp("0 1 2 1")).
• Octaves: Strudel uses scientific pitch — c4 = Ableton's “C3” (Strudel labels run one octave higher). Shift with .add(note(12)); .octave() is ignored.
• Sound-engine controls (.lpf(), .room(), .speed(), …) evaluate but are dropped — this bakes notes, not sound (do sound design on the Ableton track). The editor flags them.
• Not possible via the SDK: MPE / per-note pitch-bend / continuous automation (no such API).

Architecture (in one breath)

The Extension Host runs a bare, shared-scope V8 that breaks Strudel in-process, and the installed Host sandboxes Node (no temp files, no child process). So Strudel runs entirely in the modal webview — which already drew the live preview, and now bakes too:

Extension Host ──showModalDialog("data:…<editor.html>")──▶ webview: editor.html (CodeMirror+Strudel)
  (extension.js, ~17 kb,                                     evaluates · previews · BAKES
   no Strudel / no fs / no spawn)  ◀──close_and_send({code,bars,notes})──┘
        └─ writes notes to the clip via the SDK (createMidiClip + clip.notes = notes)

The extension is a thin client that only makes SDK calls; all Strudel lives in the webview. See FINDINGS.md for the full story (and the dead ends — including the child process that worked in Developer Mode but not when installed).

Build & run

Requires Node 24 (pinned via mise.toml) and Ableton Live 12.4.5+ Suite beta.

mise install                       # Node 24.16.0
# Obtain the Extensions SDK first — see "The SDK is not included" below.
cd extension
npm install                        # resolves the SDK + CLI from vendor/sdk/*.tgz
cp .env.example .env               # set EXTENSION_HOST_PATH to your Live beta .app
# In Live: Preferences → Extensions → enable Developer Mode, then:
npm start                          # builds + loads the extension into the running Live

Then use the context-menu actions above. More detail in extension/README.md.

To make an installable archive (Developer Mode off): cd extension && npm run package → strudelton-<version>.ablx. Pre-built .ablx files are attached to the Releases.

The SDK is not included

The Ableton Extensions SDK is confidential pre-release material and its license forbids redistributing it. So this repo does not contain it — vendor/ is gitignored. To build, obtain the SDK zip from Ableton (Centercode beta) and extract it so these exist:

vendor/sdk/ableton-extensions-sdk-1.0.0-beta.0.tgz
vendor/sdk/ableton-extensions-cli-1.0.0-beta.0.tgz

extension/package.json resolves the SDK + CLI from those paths. (The packaged .ablx bundles the SDK's runtime wrapper inside your application, which the SDK license explicitly permits.)

License

AGPL-3.0 (see LICENSE) — required because the bake engine is Strudel, which is AGPL-3.0. All of this project's own source is here.

Dependency licenses:

• @strudel/* — AGPL-3.0 (bundled into dist/editor.html only — the webview).
• @ableton-extensions/sdk — proprietary (Ableton; not included; bundled into dist/extension.js only).
• CodeMirror, @tonaljs/tonal, etc. — permissive (MIT-ish).

Strudel (AGPL) and the Ableton SDK (proprietary) are bundled into separate files — editor.html and extension.js — that only communicate across the webview boundary (a data: URL out, a JSON string back); they are never linked into one binary. The extension reads editor.html at runtime rather than import-inlining it, precisely to keep that split.