Strudel MCP Server
live-coding-music-mcp
🎵 MCP server for AI-assisted live-coding music via strudel.cc
Unofficial fan project. Not affiliated with, or endorsed by, the Strudel project. This adapter exists to make live-coding music accessible to beginners who want to try pattern-based music without learning the whole ecosystem first.
Status: Beta | 88% statement coverage | Published to npm | Actively developed
A Model Context Protocol (MCP) server that drives Strudel.cc from Claude for AI-assisted live-coding music, pattern generation, and algorithmic composition.
Current State: Beta. The core workflow (init → compose → playback → analyze) works reliably with real audio output. npm test reports ~3060 passing tests, 88.99% statement coverage / 79.99% branch coverage. CI is hardened with OpenSSF Scorecard, SHA-pinned actions, CODEOWNERS, Dependabot, and lint as a blocking gate.
What "Beta" means here:
Tool schemas are stable within minor versions; breaking changes require a major bump
Multi-session is supported as of v3.0.0 (#108) — named sessions get isolated browser, history, and audio-capture state
Upstream
@strudel/*dependencies pinned to known-good versions; Dependabot bumps gated on CIExpect hands-on iteration for non-standard patterns — report rough edges, they get fixed
Table of Contents
Features
Music control
28 MCP tools covering pattern editing, playback, audio analysis, generation, history, sessions, MIDI import/export, and Gemini-backed assists. Each tool is enum-parameterized to keep the protocol surface small:
pattern_store({ action }),edit_pattern({ mode }),transform({ op }),analyze({ include }),history({ action }),playback({ action }),effect({ action }),shape({ dimension }),audio_capture({ action }),browser_window({ action }),generate_part({ role }),generate_rhythm({ type }),music_theory({ query }),session({ action }),ai_assist({ task }), ... The 58 legacy single-verb aliases that forwarded to these were removed in v4.0.0 (#178).4 MCP resources for catalog browsing without burning tool calls:
strudel://examples,strudel://patterns,strudel://styles,strudel://docs/tools.Real browser automation of Strudel.cc through Playwright.
Multi-session support — every browser-touching tool accepts an optional
session_id; sessions have isolated browser pages, undo/redo/history stacks, and audio-capture services.Audio analysis via Web Audio API (FFT spectrum, tempo detection, key detection, rhythm complexity).
Template-based pattern generation across 8 genres (techno, house, dnb, ambient, trap, jungle, jazz, experimental); optional Gemini-backed
ai_assistfor feedback, suggestions, and jamming.Music theory helpers: 14 scales, 8 chord progression styles, euclidean and polyrhythm generation.
Pattern persistence: JSON-backed save/load with tags + the in-memory edit history (undo/redo/restore/compare).
Result envelope on every
tools/call: clients branch on{ ok, errorCategory, isRetryable }instead of parsing free-text.
Testing & CI status
~3060 passing tests:
npm testruns ~3020 unit/integration/example tests in parallel, then 36 browser-validation tests serially against real Chromium. The coverage figure below is from the first tier, which is the one CI also runs — the browser tier adds ~0.2 points and CI does not execute it, so counting it would document coverage nothing verifies.
88.99% statement coverage / 79.99% branch coverage (90.5% functions, 89.75% lines), checked against
coverage/coverage-summary.jsonby a drift guard.
Lint blocking in CI: 0 errors, ~195 warnings (mostly
anyin test mocks).OIDC trusted publishing to npm with SLSA build provenance attestation on every release.
Not Production-Ready: This is experimental software under active development. Use for exploration and experimentation. Expect breaking changes, bugs, and incomplete features. See the Contributing section to help improve it.
Example patterns
7 example patterns ship in patterns/examples/, grouped by genre:
Ambient: ambient-pad (70 BPM)
Dnb: dnb-classic (174 BPM)
House: house-classic (125 BPM)
Jazz: jazz-ii-v-i (120 BPM)
Jungle: amen-break (165 BPM)
Techno: techno-driving (130 BPM)
Trap: trap-modern (140 BPM)
Each example is a JSON file with pattern code, BPM, key, and a description, and each sets the tempo it declares (#367). See patterns/examples/README.md for details. Agents can also list these via the strudel://examples MCP resource without making any tool calls.
Migrating from @williamzujkowski/strudel-mcp-server
This project was renamed from @williamzujkowski/strudel-mcp-server to @williamzujkowski/live-coding-music-mcp to make the unofficial fan-project status unambiguous (see #97). The old package is deprecated on npm.
If you were using the old package:
# Remove old
npm uninstall -g @williamzujkowski/strudel-mcp-server
# Install new
npm install -g @williamzujkowski/live-coding-music-mcpUpdate your MCP client config. The bin name changed from strudel-mcp to live-coding-music-mcp:
// BEFORE
{
"mcpServers": {
"strudel": { "command": "strudel-mcp" }
}
}
// AFTER
{
"mcpServers": {
"live-coding-music": { "command": "live-coding-music-mcp" }
}
}The MCP server's internal identity string also changed from strudel-mcp-enhanced to live-coding-music-mcp. If you have a client that keys on that string (logs, allowlists, permission policies), update it accordingly.
All tool names and schemas are unchanged.
Installation
Prerequisites
Requirement | Version | Notes |
Node.js | 22.x+ | LTS required |
npm | 10+ | Comes with Node.js |
Chromium | Latest | Auto-installed by Playwright |
Audio output | Any | Required for playback (speakers/headphones) |
Optional: Docker for containerized deployment.
From npm
npm install -g @williamzujkowski/live-coding-music-mcp
# Install browser (required once)
npx playwright install chromiumFrom Source
# Clone repository
git clone https://github.com/williamzujkowski/live-coding-music-mcp.git
cd live-coding-music-mcp
# Install dependencies
npm install
# Install Chromium for browser automation
npx playwright install chromium
# Build the project
npm run buildQuick Start
Get from install to your first generated pattern in under two minutes.
1. Install
npm install -g @williamzujkowski/live-coding-music-mcp
npx playwright install chromium # one-timeBuilding from source instead? See Installation → From Source.
2. Configure your MCP client
Claude Desktop
Edit your Claude Desktop config file:
OS | Config path |
macOS |
|
Windows |
|
Linux |
|
Add the server:
{
"mcpServers": {
"live-coding-music": {
"command": "live-coding-music-mcp"
}
}
}Restart Claude Desktop. The server appears under the 🔌 plug icon.
Claude Code (CLI)
# If installed globally
claude mcp add strudel live-coding-music-mcp
# If built from source
claude mcp add strudel node /path/to/live-coding-music-mcp/dist/index.js3. Verify the server responds
# From a global install
echo '{"jsonrpc":"2.0","method":"tools/list","id":1}' | live-coding-music-mcp
# From source
npm run validateYou should see a JSON response listing 28 tools. If you see fewer, the build is out of date — run npm run build.
4. Make your first sound
In Claude, ask:
Initialize Strudel and compose a techno beat.
What you'll see: A Chromium window opens (visibly — this is the live editor, not a hidden process) and lands on strudel.cc. Claude calls init, then compose({ style: "techno" }). A 4-on-the-floor pattern appears in the CodeMirror editor and starts playing through your speakers.
Prefer headless mode (no browser window)? Set "headless": true in config.json before the first init call — see Configuration. Note that tempo detection currently reflects how often the agent polls rather than the audio itself (#322), in headed or headless mode alike.
5. Where to go next
Quick Reference below: tool cheat sheet for common operations.
Usage Examples: multi-step workflows (composition, audio analysis, AI-assisted jamming).
patterns/examples/: 18 ready-to-play patterns across 7 genres plus 4 longform pieces. Agents can browse them via thestrudel://examplesMCP resource without burning tool calls.
Quick Reference
Common operations as one-line tool calls:
Action | Tool call |
Initialize browser |
|
Create a techno beat in one shot |
|
Play pattern |
|
Stop playback |
|
Get current pattern |
|
Analyze audio (all features) |
|
Detect tempo only |
|
Save pattern |
|
Undo last edit |
|
Edit current pattern |
|
Create an isolated session |
|
The legacy single-verb tools (play, stop, save, undo, write, generate_pattern, ...) were deprecated aliases during the 3.0.x line and were removed in v4.0.0 (#178). Use the consolidated tools above.
One-shot workflow:
compose with style: "dnb", key: "Am", tempo: 174, auto_play: trueAvailable Tools
28 tools across 15 categories:
Tool | Description |
| Initialize Strudel in browser |
Tool | Description |
| Mutate the current session pattern. mode=write replaces the editor contents (default; mirrors the old write tool exactly, including optional pattern validation and auto_play). mode=append concatenates |
| Get current pattern code |
Tool | Description |
| Control transport on the current session. action=play starts the editor pattern. action=pause halts the clock where it is, so play resumes mid-cycle. action=stop ends playback. Example: playback({ action: "play" }). For pattern editing use edit_pattern; for tempo use set_tempo. |
| Set BPM. Writes setcpm(bpm/4), assuming one bar of 4/4 per cycle. |
Tool | Description |
| Persist patterns to disk and read them back. Use action=save to write the current session pattern under a name; action=load to restore a named pattern into the current session; action=list to enumerate the on-disk catalog (optionally filtered by tag). Example: pattern_store({ action: "save", name: "my-jam", tags: ["techno"] }). For session lifecycle (create/destroy/list active sessions) use the session tool — pattern_store deals with on-disk patterns, not runtime sessions. |
| Convert a .mid file into a playable Strudel pattern (Phase 1: literal transcription, #201). Use source="base64" with data= for inline bytes, or source="path" with data= to read from the patterns/midi/ directory (path traversal blocked). Drum tracks (MIDI channel 10) emit one s() lane per sample so simultaneous kicks/hats do not collide. Pitched tracks emit note("...").s("piano") with simultaneous notes merged into [a,b,c] chord tokens. Phase 2+ (structural compression, voice separation, LLM idiomatic pass) tracked in separate issues. Example: import_midi({ source: "path", data: "drumloop.mid", steps_per_cycle: 16 }). For the reverse direction (Strudel → MIDI) use the export_midi tool. |
Tool | Description |
| Navigate or inspect the pattern edit history. action=undo reverts the last edit on the targeted session. action=redo replays a previously-undone edit. action=list returns recent entries with timestamps and previews (limit defaults to 10). action=restore jumps the editor to a specific entry by id (current pattern goes on the undo stack). action=compare diffs two entries by id (or one entry vs current pattern). Example: history({ action: "list", limit: 5 }) — recent edits, newest first. For on-disk saved patterns use pattern_store — history deals with the in-memory edit timeline of the current session. |
Tool | Description |
| Generate, write, and play a complete pattern in one step. Auto-initializes default browser if needed. |
| Generate a single instrumental layer and append it to the current session pattern. role=drums takes |
| Generate a rhythmic pattern and append it to the current session. type=euclidean produces a Euclidean rhythm with |
Tool | Description |
| Music-theory queries. query=scale returns the notes of a scale (e.g. "C major scale: C, D, E, F, G, A, B"). query=chord_progression returns a chord progression for the key/style AND writes the resulting chord pattern into the current session. Example: music_theory({ query: "scale", root: "C", scale: "major" }). For pattern generation (drums/bass/melody) use generate_part; for rhythmic patterns use generate_rhythm. |
Tool | Description |
| Apply a single transform op to the current session pattern. op=transpose shifts notes by |
| Add or remove a Strudel effect on the current session pattern. action=add appends |
| Shape the current pattern along one of three high-level dimensions. dimension=mood applies a mood profile (dark/euphoric/melancholic/aggressive/dreamy/peaceful/energetic) with optional intensity 0-1. dimension=energy applies an energy level (integer 0-10). dimension=refine applies a directional refinement: faster/slower/louder/quieter/brighter/darker/"more reverb"/drier. All three auto-play by default. Example: shape({ dimension: "mood", target_mood: "dark", intensity: 0.8 }). For raw transform ops use transform; for explicit effects use effect. |
Tool | Description |
| Gemini-backed pattern assistance. task=feedback returns creative critique on the current pattern (optionally with audio analysis). task=suggest analyzes the currently playing audio and suggests a complementary Strudel pattern as text (not auto-executed). task=jam generates a fresh layer (drums/bass/melody/pad/texture) and merges it into the current pattern, then auto-plays. All three share Gemini auth + rate limiting. Example: ai_assist({ task: "jam", layer: "bass" }). Needs GEMINI_API_KEY, or a logged-in claude/agy/codex CLI on PATH (#252). For non-AI pattern generation use generate_part; for full compositions use compose. |
Tool | Description |
| Audio analysis on the currently-playing pattern. include=["all"] (default) returns the full spectrum + features object, matching the pre-consolidation behaviour. include=["tempo"] returns only BPM with confidence. include=["key"] returns detected key + scale + confidence. include=["spectrum"] returns FFT features (bass, mid, treble, brightness, etc.). include=["rhythm"] returns rhythm-only analysis (complexity, density, syncopation). Combining values returns an object keyed by category, e.g. analyze({ include: ["tempo", "key"] }) → { tempo: {...}, key: {...} }. Example: analyze({ include: ["tempo"] }) to cheaply re-check BPM during a session. For static pattern analysis (no browser) use analyze_pattern_local; for runtime validation use validate_pattern_runtime. |
| Validate pattern with runtime error checking (monitors Strudel console for errors) |
| Validate pattern syntax against the local StrudelEngine, which runs in a sandboxed child process (no browser required) |
| Static analysis (events/cycle, complexity, optional BPM) without browser playback |
| Enumerate events the pattern would emit between two cycle indices (max 16 cycles) |
| Transpile pattern source via StrudelEngine; returns transpiled code or syntax error |
Tool | Description |
| Manage isolated Strudel browser sessions (multi-session, #108). action=create starts a new named session (sessions share one browser but isolated contexts). action=destroy closes a named session and releases its resources. action=list returns metadata for all active sessions (id, created, last_activity, is_playing, is_default). action=switch changes the default session that subsequent tool calls route to when no session_id is passed. Example: session({ action: "create", session_id: "live-set-1" }). For the on-disk pattern catalog use pattern_store(action=list) — session(action=list) lists runtime sessions, not saved patterns. |
Tool | Description |
| Export current pattern to MIDI file. Parses note(), n(), and chord() functions. |
| Interact with the visible Strudel browser window. action=show brings the window to the foreground. action=screenshot captures the current editor view to disk (optional |
Tool | Description |
| Record audio output from the live Strudel session. action=start begins streaming capture (optional |
Tool | Description |
| Inspect server and browser state. level=status returns a quick state snapshot (cache read, <15ms SLA), plus which config.json was read and any warnings from it. level=full returns detailed browser diagnostics including caches, errors, and performance. level=perf returns server-side timing metrics + top bottlenecks. level=memory returns process memory usage. level=errors returns captured console errors and warnings from Strudel. Default level=full preserves the pre-consolidation behaviour. Example: diagnostics({ level: "status" }) — millisecond-cheap. For screenshots use browser_window; for tool listings use the strudel://docs/tools resource. |
Tool | Description |
| Record a window of live Strudel audio and write it to a file. Returns a path plus what was actually recorded, not a wall of base64 — prefer this over audio_capture when you want the audio to exist somewhere. format=wav (default) decodes to 16-bit PCM a DAW will open; format=webm writes the raw Opus recording. Reports silent captures instead of writing a silent file and claiming success. Audio must already be playing: call playback({ action: "play" }) first. Example: export_audio({ duration: 4000, filename: "take-01" }). |
Auto-generated from source. 28 tools registered.
Usage Examples
Basic Pattern Creation
Create a Simple Beat
You: Initialize Strudel and create a simple techno beat
Claude: [Initializes browser]
[Generates and writes pattern]
[Starts playback]
Pattern created:
setcpm(130/4)
stack(
s("bd*4"),
s("~ cp ~ cp"),
s("hh*8").gain(0.4)
).gain(0.8)Generate a Bassline
You: Add a techno bassline in C
Claude: [Generates bassline]
[Appends to current pattern]
Added: note("c2 c2 c2 c2").s("sawtooth").cutoff(800)Advanced Music Generation
Jazz Composition
You: Create a jazz progression in F major with a walking bass
Claude: Generated progression: "Gm7" "C7" "Fmaj7"
Pattern:
stack(
note("Gm7" "C7" "Fmaj7").struct("1 ~ ~ ~").s("piano"),
note("g2 c2 f2").s("sine").gain(0.7)
)Drum & Bass Track
You: Generate a complete drum & bass track at 174 BPM
Claude: [Creates multi-layer pattern with drums, bass, and pads]
// dnb pattern in C at 174 BPM
setcpm(174/4)
stack(
// Drums
s("bd ~ ~ [bd bd] ~ ~ bd ~, ~ ~ cp ~ ~ cp ~ ~").fast(2),
// Bass
note("c1 ~ ~ c2 ~ c1 ~ ~").s("square").cutoff(400),
// Pads (atmospheric)
note("c3 eb3 g3 bb3").s("sawtooth")
.attack(2).release(4).room(0.8).gain(0.6)
)Real-Time Manipulation
Live Audio Analysis
You: Analyze what's playing and show me the frequency breakdown
Claude: Audio Analysis Results:
{
"connected": true,
"features": {
"average": 78.5,
"peak": 180,
"peakFrequency": 120,
"bass": 145,
"mid": 82,
"treble": 45,
"isPlaying": true,
"brightness": "balanced"
}
}
Strong bass presence detected - typical for techno/house patterns.Pattern Variations
You: Create a glitchy variation of the current pattern
Claude: [Applies glitch transformation]
Added: .sometimes(x => x.chop(8).rev).rarely(x => x.speed(-1))Multi-Track Composition
Layered Ambient Track
You: Create an ambient soundscape with multiple layers
Claude: [Generates complex multi-layer pattern]
setcpm(90/4)
stack(
// Deep bass drone
note("c1").s("sine").attack(4).release(8).gain(0.5),
// Texture pad
note("c3 eb3 g3").s("sawtooth")
.attack(2).release(6).room(0.9).gain(0.4),
// Sparse percussion
s("bd ~ ~ ~, ~ ~ ~ hh:8").room(0.9).gain(0.3),
// Melodic sparkles
note("c5 g5 eb5 bb5").struct("~ 1 ~ 1 ~ ~ 1 ~")
.s("triangle").delay(0.5).room(0.8).gain(0.3)
)Session Management
Save and Load Patterns
You: Save this pattern as "techno-groove-1" with tags "techno" and "experimental"
Claude: Pattern saved as "techno-groove-1"
---
You: List all my techno patterns
Claude: Saved patterns with tag "techno":
• techno-groove-1 [techno, experimental] - 2025-10-23T19:30:00.000Z
• acid-bassline [techno, acid] - 2025-10-23T18:15:00.000Z
---
You: Load "acid-bassline"
Claude: Loaded pattern "acid-bassline"
[Pattern written to editor]Music Theory Applications
Generate Euclidean Rhythms
You: Create a 5/8 euclidean rhythm with kick drum
Claude: Generated Euclidean rhythm (5/8)
Pattern: s("bd").struct("1 ~ 1 ~ 1 1 ~ 1")Complex Polyrhythms
You: Generate a polyrhythm with kick (4/16), snare (7/16), and hi-hat (3/16)
Claude: Generated polyrhythm
stack(
s("bd").euclid(4, 16),
s("cp").euclid(7, 16),
s("hh").euclid(3, 16)
)Integration with LLM Agents
AI-Assisted Composition
You: Analyze the mood of my current pattern and suggest complementary elements
Claude: [Analyzes pattern structure and audio features]
Your pattern has:
- Energetic rhythm (130 BPM)
- Strong bass presence
- Minimal melodic content
Suggestions:
1. Add arpeggiated synth for movement
2. Include occasional breaks/fills
3. Layer atmospheric pad for depth
Would you like me to add any of these?
You: Add an arpeggiated synth in C minor
Claude: [Generates and adds]
note("c4 eb4 g4 bb4 c5").struct("1 1 1 1 1 1 1 1")
.s("triangle").delay(0.25).room(0.3).gain(0.5)Testing
Tools are exercised against real Strudel.cc interaction through the browser test suite; those are skipped in CI (require Playwright + audio) but run locally:
# Run integration tests
npm run test:integration
# Run browser tests
node tests/strudel-integration.js
# Run npm test to see current pass/fail/skip countsConfiguration
config.json
{
"headless": false, // Set true for background operation
"strudel_url": "https://strudel.cc/",
"patterns_dir": "./patterns",
"exports_dir": "./exports",
"audio_analysis": {
"fft_size": 2048, // power of 2 in [32, 32768]; code default is 1024
"smoothing": 0.8 // number in [0, 1]; default 0.8
}
}strudel_url is the REPL the browser is pointed at — set it to run against a self-hosted or
pinned Strudel build. Only http/https are accepted; anything else falls back to the default
with a logged warning. patterns_dir is where pattern_store reads and writes.
exports_dir is where export_midi({format:"file"}) writes. Exported filenames are reduced to a
basename and confined to this directory — a name containing path separators is sanitized rather
than honoured, and the response reports the path actually written.
Unknown top-level keys are logged as warnings at startup rather than silently ignored.
audio_analysis.fft_size tunes the FFT bin count on the AnalyserNode attached to Strudel's audio graph — larger = better frequency resolution at higher CPU cost. smoothing is the analyser's smoothingTimeConstant (higher = steadier spectrum, more lag). Invalid values fall back to defaults with a warning; the frequency-band boundaries inside analyze rescale automatically so band Hz coverage stays consistent across FFT sizes.
Architecture
The server is a thin MCP dispatcher (src/server/server.ts, ~520 lines) over twelve per-domain tool modules (src/server/tools/*.ts), ten services (MusicTheory, PatternGenerator, SessionManager, AudioCaptureService, AudioExportService, GeminiService, MIDIExportService, MIDIImportService, StrudelEngine, PatternSandbox) plus a provider-agnostic AI transport layer (src/services/ai/), two controllers (StrudelController for Playwright, AudioAnalyzer for Web Audio API), and a JSON-on-disk PatternStore. Browser automation drives the editor on strudel.cc through window.strudelMirror.editor.dispatch(...) rather than keyboard simulation — about 80% faster.
For the full breakdown — component diagram, per-component responsibilities, directory layout, data flow, and optimization strategies — see ARCHITECTURE.md.
Pattern Examples
Minimal Techno (Verified Working)
setcpm(130/4)
stack(
s("bd*4").gain(0.9),
s("~ cp ~ cp").room(0.2),
s("hh*16").gain(0.4).pan(sine.range(-0.5, 0.5)),
note("c2 c2 eb2 c2").s("sawtooth").cutoff(800)
).swing(0.05)Drum & Bass (Verified Working)
setcpm(174/4)
stack(
s("bd ~ ~ [bd bd] ~ ~ bd ~, ~ ~ sn:3 ~ ~ sn:3 ~ ~").fast(2),
s("hh*16").gain(0.5),
note("e1 ~ ~ e2 ~ e1 ~ ~").s("sine:2").lpf(200)
)Generated Jazz Progression
// Jazz ii-V-I in F
stack(
note("Gm7" "C7" "Fmaj7").struct("1 ~ ~ ~").s("piano"),
note("g2 c2 f2").s("sine").gain(0.7)
)Docker Support
# Build image
docker build -t live-coding-music-mcp .
# Run container
docker run -it --rm live-coding-music-mcp
# Or use docker-compose
docker-compose upDevelopment
For development setup, scripts, debugging, adding new tools, and the release process, see DEVELOPMENT.md.
Quick links:
Setup —
git clonetonpm testAdding new tools — module pattern + envelope helpers
Release process —
gh release createtriggers the publish workflowContributing — commit conventions and PR flow
The Configuration section above covers runtime config (config.json). ARCHITECTURE.md covers the system design.
Performance
Measured against the current StrudelController cache + Strudel.cc on a developer machine:
Operation | Latency |
Browser initialization | 1.5–2 s (with resource blocking) |
Pattern write | 50–80 ms (cached CodeMirror editor access) |
Pattern read (cached) | 10–15 ms |
Play / pause / stop | 100–150 ms |
Audio analysis (single FFT) | 10–15 ms |
Tempo detection | <100 ms (onset-based; reports poll cadence, not tempo — #322) |
Key detection | <100 ms (Krumhansl-Schmuckler, Pearson; bass-register accuracy depends on |
Pattern generation | <100 ms (template-based) |
Process resident memory | ~120–150 MB |
Advanced Usage
Custom Music Theory
Create Custom Scales
// The MusicTheory service supports 15+ built-in scales
// You can request any combination:
You: Generate a lydian scale starting on D
Claude: D lydian scale: D, E, F#, G#, A, B, C#Complex Chord Progressions
You: Create a jazz ii-V-I progression in Bb with extended voicings
Claude: Generated jazz progression in Bb: "Cm7" "F7" "Bbmaj7"
Pattern:
note("Cm7" "F7" "Bbmaj7")
.struct("1 ~ ~ ~")
.s("sawtooth")
.add(note("7")) // Add 7th extensions
.room(0.4)Advanced Rhythm Techniques
Euclidean Patterns
You: Create a complex polyrhythm using euclidean patterns:
- Bass drum: 7 hits in 16 steps
- Snare: 5 hits in 16 steps
- Hi-hat: 11 hits in 16 steps
Claude: [Generates mathematically perfect polyrhythm]
stack(
s("bd").euclid(7, 16),
s("cp").euclid(5, 16),
s("hh").euclid(11, 16)
)Generative Variations
You: Create 3 variations of my current pattern: subtle, moderate, and glitchy
Claude: [Generates three variants]
Version 1 (subtle):
original.sometimes(x => x.fast(2))
Version 2 (moderate):
original.every(4, x => x.rev).sometimes(x => x.fast(2))
Version 3 (glitchy):
original.sometimes(x => x.chop(8).rev).rarely(x => x.speed(-1))Performance Optimization Tips
Pattern Caching
// The server caches patterns intelligently:
// - Generated patterns stored before browser init
// - Editor content cached for 100ms
// - Audio analysis cached for 50ms
// For fastest performance:
1. Generate patterns before initializing browser
2. Initialize once and reuse the session
3. Batch multiple changes togetherHeadless Mode
// In config.json:
{
"headless": true, // Faster, no GUI
"strudel_url": "https://strudel.cc/",
"patterns_dir": "./patterns"
}Integration Patterns
Workflow Automation
You: Create a complete track:
1. Start with techno drums at 130 BPM
2. Add acid bassline in E
3. Layer ambient pads
4. Save as "track-001" with tags "techno", "acid", "experimental"
Claude: [Executes full workflow]
[Initializes browser]
[Generates drum pattern]
[Adds bassline]
[Layers pads]
[Saves with metadata]
Complete! Pattern saved as "track-001"Audio-Reactive Composition
You: Monitor the audio and suggest adjustments based on frequency balance
Claude: [Analyzes current playback]
Analysis shows:
- Bass: 180 (strong)
- Mid: 45 (weak)
- Treble: 30 (weak)
Recommendations:
1. Reduce bass gain by 20%
2. Add mid-range melodic content
3. Include hi-hat pattern for treble
Apply changes? [Yes/No]Advanced Pattern Manipulation
Dynamic Transformations
You: Apply these transformations in sequence:
1. Transpose up 3 semitones
2. Add 10% humanization
3. Apply reverb with 0.6 room size
4. Every 4th cycle, reverse the pattern
Claude: [Applies transformations]
Final pattern:
[original]
.transpose(3)
.nudge(rand.range(-0.1, 0.1))
.room(0.6)
.every(4, x => x.rev)Conditional Logic
You: Create a pattern that evolves:
- Bars 1-4: Simple kick pattern
- Bars 5-8: Add snare
- Bars 9-16: Add full drum kit
- Then loop with variations
Claude: [Generates evolving pattern]
s("bd*4")
.struct("1 ~ ~ ~")
.mask("<1 1 1 1 0 0 0 0>/4") // First 4 bars
.stack(
s("~ cp ~ cp")
.mask("<0 0 0 0 1 1 1 1>/8") // Bars 5-8
)
// Full complexity from bar 9
.every(8, x => x.sometimes(y => y.fast(2)))Security
Pattern Validation
All patterns are validated before execution:
Dangerous gain levels (>2.0) are flagged
Eval blocks are rejected
Path traversal attacks are blocked in PatternStore
Browser Isolation
Be precise about what this does and does not give you:
The OS-level Chrome sandbox is disabled. Chromium is launched with
--no-sandboxand--disable-setuid-sandbox(src/StrudelController.ts) for headless and container compatibility, where the sandbox otherwise needsCAP_SYS_ADMINor user namespaces. This is a deliberate trade-off, not a security feature.The browser context is a fresh, non-persistent Playwright context — no profile on disk, no cookies or storage carried over between runs, and no
file://navigation is ever performed.Resource blocking is a performance optimization, not a security boundary. Images, fonts, and media are aborted to speed up page load; scripts, stylesheets, and network requests from strudel.cc are allowed through as normal.
Patterns are validated before execution (see above), which is the actual pre-execution control.
If you need real isolation, run the whole MCP server inside a locked-down container or VM. The server does not sandbox itself.
Known Limitations
No authentication: The MCP server trusts all incoming requests
Local only: Designed for local development, not network deployment
Pattern execution: Patterns execute in browser context with audio access
Reporting Security Issues
Found a vulnerability? Please open a security issue or email the maintainer directly. Do not disclose publicly until patched.
Troubleshooting
Common Issues
Browser doesn't open
Symptom: Error: Browser not initialized or Chromium launch fails
Solutions:
# Install Chromium for Playwright
npx playwright install chromium
# If that fails, try installing all browsers
npx playwright install
# Check Playwright installation
npx playwright --version
# For Linux, install dependencies
sudo npx playwright install-deps chromiumAudio analysis returns "not connected"
Symptom: Audio analysis shows connected: false
Solutions:
Ensure pattern is playing first:
You: Play the pattern, wait 2 seconds, then analyzeReinitialize the browser:
You: Stop, close the browser, reinitialize, and try againCheck audio context activation:
Audio contexts require user interaction on some systems
The browser window must be visible (not headless) for first run
Pattern syntax errors
Symptom: Pattern doesn't play or shows errors in console
Solutions:
Common issues:
1. Missing quotes: s(bd*4) → s("bd*4")
2. Unmatched parentheses: stack(s("bd")) → stack(s("bd")))
3. Invalid note names: note("h2") → note("c2")
Test with minimal pattern first:
s("bd*4")
Then build complexity gradually.MCP connection issues
Symptom: Claude can't find the server or tools
Solutions:
# Verify server is built
npm run build
# Check if server responds
echo '{"jsonrpc":"2.0","method":"tools/list","id":1}' | node dist/index.js
# Should return JSON with 28 tools
# Reinstall MCP server in Claude
claude mcp remove strudel
claude mcp add strudel node $(pwd)/dist/index.js
# Restart Claude
claude chatPerformance issues / Slow response
Symptom: Operations take longer than expected
Solutions:
Enable caching (default, but verify):
Editor caching: 100ms TTL
Audio analysis: 50ms TTL
Use headless mode for faster operation:
// config.json { "headless": true }Batch operations:
Instead of: - Add drums - Add bass - Add melody Do: - Generate complete pattern with drums, bass, and melodyReduce browser overhead:
Close other browser instances
Disable browser DevTools
Use resource blocking (enabled by default)
Patterns not saving
Symptom: pattern_store({ action: "save" }) fails or patterns don't persist
Solutions:
# Check patterns directory exists
ls -la ./patterns
# Create manually if needed
mkdir -p ./patterns
# Verify write permissions
touch ./patterns/test.json
rm ./patterns/test.json
# Check for invalid pattern names
# Valid: "techno-beat-1", "my_pattern", "track001"
# Invalid: "pattern/with/slashes", "name:with:colons"Platform-Specific Issues
macOS
# Keyboard shortcut uses Meta (Cmd) key
# Already handled by ControlOrMeta
# If Chromium crashes on M1/M2:
npx playwright install chromium --with-depsLinux
# Install system dependencies
sudo npx playwright install-deps chromium
# If running in Docker/headless environment:
# Ensure config.json has headless: trueWindows
# Use PowerShell or Git Bash
# Paths should use forward slashes in config.json
# If Chromium doesn't launch:
npx playwright install chromiumDebugging Tips
Enable Verbose Logging
# Set environment variable
DEBUG=* node dist/index.js
# Or in Claude:
You: Enable detailed logging for the next operationCheck Browser State
You: Show me the current browser initialization state
and any cached patterns
Claude: Browser state:
- Initialized: true
- Cached patterns: 2
- Undo stack depth: 5
- Last operation: edit_pattern (2.5s ago)Validate Pattern Syntax
You: Before playing, validate this pattern syntax:
s("bd*4, ~ cp ~ cp")
Claude: [Checks syntax]
Valid Strudel pattern.
Ready to play.Getting Help
If you encounter issues not covered here:
Check existing issues: GitHub Issues
Run integration tests:
npm run test:integrationEnable debug mode:
DEBUG=* npm startConsult Strudel docs: Strudel.cc documentation
Create new issue: Include error messages, OS, Node version, and steps to reproduce
Contributing
PRs welcome — bug fixes, docs, tests, new tools. See CONTRIBUTING.md for the contribution guide and DEVELOPMENT.md for setup and workflow.
For non-trivial work, open a GitHub issue first (issue policy in CLAUDE.md). For typos and small fixes, a PR directly is fine.
GitHub Discussions are open for use-case questions and design conversations.
License
AGPL-3.0-or-later — see LICENSE for the full text.
This project depends on @strudel/core, @strudel/mini, @strudel/tonal, and @strudel/transpiler, which are AGPL-3.0 licensed by the upstream Strudel project. Since we import from those packages and redistribute the combined work via npm, this project must be distributed under the same copyleft terms. If you fork or redistribute, you must keep the AGPL license and provide source access to any network-accessible users (AGPL §13).
Earlier versions of this package (including @williamzujkowski/strudel-mcp-server prior to deprecation) shipped with an MIT declaration — that was incorrect given the AGPL dependencies. v2.0.0 of @williamzujkowski/live-coding-music-mcp corrects the license to AGPL-3.0-or-later. v1.0.0 of this package is deprecated; install v2.0.0 or later (current: v4.0.0).
Acknowledgments
Strudel.cc — pattern-based live coding environment (this project is a fan adapter, not affiliated)
TidalCycles — original pattern language Strudel descends from
Anthropic — Claude and the MCP protocol
Playwright — browser automation
v4.0.0 — Open source, AGPL-3.0-or-later, experimental | Report issues | Contribute
This project is under active development. Core features work, but expect bugs and breaking changes. Not recommended for production use.
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