strudel-scalenav

Connect your Strudel live-coding patterns to Scale Navigator ensembles. Sign in, join a live room, and receive the host's current scale, chord, and BPM as live values you can sample in your Strudel patterns — so your algorithmic music stays harmonically locked to whoever's driving the ensemble.

• Read-only client. Strudel users consume harmonic state; the host still drives.
• Live. Updates stream via Firestore onSnapshot, so pattern output follows the host in real time.
• Signed in. Google or email/password — your display name shows up in the ensemble alongside Dashboard users.
• MIT-licensed, one-line import from the Strudel REPL.

Quick start

Paste this into strudel.cc:

const { signInWithGoogle, joinEnsemble, getCurrentUser } = await import('https://cdn.jsdelivr.net/npm/strudel-scalenav@0.6.1/dist/strudel-scalenav.js')
if (!getCurrentUser()) await signInWithGoogle()
const ens = await joinEnsemble('your-room-id')

n("0 2 4 <[6,8] [7,9]>")
  .scale(ens.strudelScale)
  .sound("piano")

Whenever the Scale Navigator host changes the scale or chord, your pattern reharmonizes on the next cycle — no re-evaluation needed.

Installation

In the Strudel REPL (the normal case)

const sn = await import('https://cdn.jsdelivr.net/npm/strudel-scalenav@0.6.1/dist/strudel-scalenav.js')

In a Vite / bundler project using @strudel/core

npm install strudel-scalenav firebase

import { joinEnsemble, signInWithGoogle } from 'strudel-scalenav'

You must have @strudel/core's signal available in global scope (the REPL does this for you; in a bundler project, expose it yourself: globalThis.signal = signal).

Signing in

Sign-in is required. Everyone who joins an ensemble shows up to the host by name. Pick one:

await signInWithGoogle()
// or
await signUpWithEmail('you@example.com', 'your-password', 'Your Display Name')
// or (for returning users)
await signInWithEmail('you@example.com', 'your-password')

Check if you're already signed in:

const user = getCurrentUser()
if (!user) await signInWithGoogle()

Joining an ensemble

You need a room ID. The host gets this when they create an ensemble in the Scale Navigator Dashboard or mobile app.

const ens = await joinEnsemble('nathan-jam-session')

Leave gracefully:

await ens.leave()

The ens API

Hierarchical API (recommended)

The API is organized into clear namespaces: ens.scale.* and ens.chord.*.

ens.scale.*

ens.scale.thirds.*

Stack thirds from the scale root (index 0 of the scale). Uses the current scale root, not the chord root.

ens.chord.voicing.*

Access the host's original chord voicing (preserves octave placement).

ens.chord.closed.*

Close-position chord (all pitch classes in octave 4).

ens.chord.thirds.*

Stack thirds from the chord root using the current scale. Continues up in octaves (9th is above 7th, not wrapped back down).

Stacked thirds index reference:

All index methods support negative indices: -1 = last, -2 = second to last, etc.

Flat API (aliases)

For backwards compatibility and quick access, flat methods are also available. Prefer the hierarchical API for new code.

Scale data

Chord data

Other

Visual helpers

Options for showBadge: x (default 480), y (default 38), size (default 26), showText (default true)

note(ens.chord.voicing.arp(4)).s("piano")           // 4 notes per cycle
note(ens.chord.voicing.block()).s("piano").slow(2)  // block chord

Auth functions

Pattern recipes

Play in the host's scale

n("0 2 4 <[6,8] [7,9]>")
  .scale(ens.strudelScale)
  .sound("piano")

Arpeggiate the chord voicing

note(ens.chord.voicing.arp(4)).sound("piano")

Arpeggiate stacked thirds (1-3-5-7...)

note(ens.chord.thirds.arp(4)).sound("piano")

Chord with bass note

stack(
  note(ens.chordRootNote).slow(2),   // bass
  note(ens.chord.voicing.arp(4))     // arpeggio
).sound("piano")

Block chords

note(ens.chord.voicing.block())
  .struct("x ~ x ~ x x ~ x")
  .sound("piano")

Block chord of stacked thirds (7th chord)

note(ens.chord.thirds.block(4))  // root, 3rd, 5th, 7th
  .struct("x ~ x ~")
  .sound("piano")

Generative melody

n(irand(8).segment(8))
  .scale(ens.strudelScale)
  .sound("piano")

Arpeggiate the scale itself

note(ens.scale.arp(8)).sound("piano")

Sync to host's BPM

note(ens.chord.voicing.arp(4))
  .sound("piano")
  .cpm(ens.bpm.div(4))

Display scale badge

ens.showBadge()  // Shows polygon + scale/chord names in header

n("0 2 4 6")
  .scale(ens.strudelScale)
  .sound("piano")

The badge automatically positions to the right of "REPL (warm)" and updates when scale/chord changes.

Caveats

• Scale → Strudel mapping. All 7 pressing scale classes map to Strudel equivalents: diatonic → major, harmonic_minor → harmonic minor, harmonic_major → harmonic major, acoustic → lydian dominant, whole_tone → whole tone, octatonic → diminished, hexatonic → augmented.
• Read-only. This package never writes changes back to the room.
• Auth required. Anonymous access isn't enabled.

Development

git clone https://github.com/nathanturczan/strudel-scalenav
cd strudel-scalenav
npm install
npm run build

Publishing

npm run build
npm publish

Related

• Scale Navigator Dashboard — the host app
• Strudel — browser-based live coding
• TidalCycles — the pattern language Strudel ports to JS

License

MIT © Nathan Turczan. See LICENSE.