Strudel MCP Server

🎵 Open source MCP server for AI-powered music generation with Strudel.cc

Status: Actively developed | Experimental | Contributions welcome

An experimental Model Context Protocol (MCP) server that enables Claude to control Strudel.cc for AI-assisted music generation, live coding, and algorithmic composition.

Current State: Functional but under active development. Core features work reliably, but expect rough edges. Test coverage is at 78% with 1470 tests passing (1521 total, 51 skipped). See open issues for known limitations.

Table of Contents

• Features
• Installation
• Quick Reference
• Quick Start
• Available Tools
• Usage Examples
• Architecture
• Advanced Usage
• Configuration
• Security
• Troubleshooting
• Development
• Contributing

✨ Features

🎹 Complete Music Control

• 65 MCP Tools: Comprehensive suite for music creation and manipulation
• Real Browser Automation: Direct control of Strudel.cc through Playwright
• Live Audio Analysis: Real-time frequency analysis via Web Audio API
• Pattern Generation: AI-powered creation across 8+ music genres
• Music Theory Engine: Scales, chords, progressions, euclidean rhythms
• Session Management: Save, load, undo/redo with pattern storage

🔧 Testing & Development Status

• ✅ Test Suite: 1470 tests passing (1521 total, 51 skipped)
• ✅ Code Coverage: 78% statement coverage (goal: 80%)
• ✅ Browser Integration: Works with live Strudel.cc website
• ✅ Audio Analysis: Real-time FFT analysis functional
• ✅ Pattern Generation: Core music generation features working
• ✅ OIDC Publishing: Secure npm publishing with provenance attestation

Not Production-Ready: This is experimental software under active development. Use for exploration and experimentation. Expect breaking changes, bugs, and incomplete features. See CONTRIBUTING.md to help improve it.

🎼 Example Patterns

Explore 17 curated example patterns across 10 genres in patterns/examples/:

• Techno: Hard techno, minimal techno
• House: Deep house, tech house
• Drum & Bass: Liquid, neurofunk
• Ambient: Dark ambient, drone
• Trap: Modern trap, cloud trap
• Jungle: Classic jungle, ragga jungle
• Jazz: Bebop, modal jazz
• Intelligent DnB: Atmospheric, liquid, LTJ Bukem style
• Trip Hop: Portishead, Massive Attack, Flying Lotus style
• Boom Bap: DJ Premier, Alchemist, golden era hip hop

Each example includes pattern code, BPM, key, and description. See patterns/examples/README.md for details.

📦 Installation

Prerequisites

| Requirement | Version | Notes | |-------------|---------|-------| | Node.js | 18.x or 20.x | LTS versions recommended | | npm | 9+ | 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/strudel-mcp-server

# Install browser (required once)
npx playwright install chromium

From Source

# Clone repository
git clone https://github.com/williamzujkowski/strudel-mcp-server.git
cd strudel-mcp-server

# Install dependencies
npm install

# Install Chromium for browser automation
npx playwright install chromium

# Build the project
npm run build

🚀 Quick Reference

Common commands for immediate use:

| Action | Command | |--------|---------| | Initialize browser | init | | Create techno beat | generate_pattern with style: "techno" | | Play pattern | play | | Stop playback | stop | | Get current pattern | get_pattern | | Analyze audio | analyze | | Save pattern | save with name: "my-pattern" | | Undo last change | undo |

One-shot workflow:

compose with style: "dnb", key: "Am", bpm: 174, auto_play: true

🎯 Quick Start

1. Add to Claude

# If installed globally
claude mcp add strudel strudel-mcp

# If built from source
claude mcp add strudel node /path/to/strudel-mcp-server/dist/index.js

2. Start Using

claude chat

Then ask Claude:

• "Initialize Strudel and create a techno beat"
• "Generate a jazz chord progression in F major"
• "Create a drum & bass pattern at 174 BPM"

🛠️ Available Tools (65)

Core Control (10 tools)

| Tool | Description | Example | |------|-------------|---------| | init | Initialize Strudel in browser | "Initialize Strudel" | | write | Write pattern to editor | "Write pattern: s('bd*4')" | | play | Start playback | "Play the pattern" | | stop | Stop playback | "Stop playing" | | clear | Clear editor | "Clear the editor" | | get_pattern | Get current pattern | "Show current pattern" | | append | Add to pattern | "Add hi-hats" | | insert | Insert at line | "Insert at line 2" | | replace | Replace text | "Replace bd with sn" | | pause | Pause playback | "Pause" |

Pattern Generation & Manipulation (10 tools)

| Tool | Description | Options | |------|-------------|---------| | generate_pattern | Complete patterns | techno, house, dnb, ambient, trap, jungle, jazz, intelligent_dnb, trip_hop, boom_bap | | generate_drums | Drum patterns | All styles + complexity (0-1) | | generate_bassline | Bass patterns | techno, house, dnb, acid, dub, funk, jazz, intelligent_dnb, trip_hop, boom_bap | | generate_melody | Melodic lines | Any scale, custom length | | generate_variation | Pattern variations | subtle, moderate, extreme, glitch | | transpose | Transpose notes | ±12 semitones | | reverse | Reverse pattern | - | | stretch | Time stretch | Factor 0.1-10 | | quantize | Quantize to grid | 1/4, 1/8, 1/16, etc. | | humanize | Add timing variation | Amount 0-1 |

Music Theory (6 tools)

| Tool | Description | Options | |------|-------------|---------| | generate_scale | Generate scales | major, minor, modes, pentatonic, blues | | generate_chord_progression | Chord progressions | pop, jazz, blues, rock, folk | | generate_euclidean | Euclidean rhythms | hits/steps/sound | | generate_polyrhythm | Polyrhythms | Multiple patterns | | generate_fill | Generate drum fills | All styles, 1-4 bars | | apply_scale | Apply scale to notes | Any scale |

Effects (4 tools)

| Tool | Description | |------|-------------| | add_effect | Add audio effect (reverb, delay, etc.) | | remove_effect | Remove an effect from the chain | | set_tempo | Set BPM (60-200) | | add_swing | Add swing feel (0-1 amount) |

Session Management (5 tools)

| Tool | Description | |------|-------------| | save | Save pattern with tags | | load | Load saved pattern | | list | List all patterns | | undo | Undo last action | | redo | Redo action |

Pattern History (3 tools)

| Tool | Description | |------|-------------| | list_history | Browse pattern history with timestamps and previews | | restore_history | Restore a previous pattern by ID | | compare_patterns | Compare two patterns showing line-by-line differences |

Audio Analysis (6 tools)

| Tool | Description | |------|-------------| | analyze | Basic audio analysis (frequency, playing state) | | analyze_spectrum | FFT spectral analysis | | analyze_rhythm | Rhythm complexity analysis | | detect_tempo | BPM detection | | detect_key | Musical key detection | | validate_pattern_runtime | Validate pattern with browser error checking |

UX & Browser Control (6 tools)

| Tool | Description | |------|-------------| | compose | One-shot pattern generation with auto-play | | status | Get current browser/playback state | | diagnostics | Detailed system diagnostics | | show_browser | Bring browser window to foreground | | screenshot | Capture browser screenshot | | show_errors | Display captured console errors |

Performance (2 tools)

| Tool | Description | |------|-------------| | performance_report | Timing metrics and bottleneck analysis | | memory_usage | Memory consumption statistics |

AI Feedback (1 tool)

| Tool | Description | Options | |------|-------------|---------| | get_pattern_feedback | AI-powered creative feedback via Gemini | includeAudio: analyze audio (default: false), style: hint for context |

Note: Requires GEMINI_API_KEY environment variable. Returns pattern complexity, estimated style, strengths, and suggestions.

🎵 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)
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)
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)
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

All tools have been tested with real Strudel.cc interaction:

# Run integration tests
npm run test:integration

# Run browser tests
node tests/strudel-integration.js

# Test results: 1470/1521 tests passing (96.6%), 51 skipped (browser tests in CI)

⚙️ Configuration

config.json

{
  "headless": false,        // Set true for background operation
  "strudel_url": "https://strudel.cc/",
  "patterns_dir": "./patterns",
  "audio_analysis": {
    "fft_size": 2048,
    "smoothing": 0.8
  }
}

🏗️ Architecture

System Overview

The Strudel MCP Server is built with a modular architecture that separates concerns and enables robust music generation:

┌─────────────────────────────────────────────────────────────┐
│                       Claude AI                              │
│                  (MCP Client)                                │
└───────────────────────┬─────────────────────────────────────┘
                        │ MCP Protocol (stdio)
                        │
┌───────────────────────▼─────────────────────────────────────┐
│              EnhancedMCPServerFixed                          │
│  ┌────────────────────────────────────────────────────────┐ │
│  │  Tool Request Handler                                  │ │
│  │  - Validates inputs                                    │ │
│  │  - Routes to appropriate service                       │ │
│  │  - Handles errors gracefully                           │ │
│  └────────────────────────────────────────────────────────┘ │
└───────┬────────────┬────────────┬───────────┬──────────────┘
        │            │            │           │
   ┌────▼────┐  ┌───▼────┐  ┌───▼────┐  ┌──▼──────┐
   │ Strudel │  │ Music  │  │Pattern │  │ Pattern │
   │Controller│  │ Theory │  │Generator│  │  Store  │
   └────┬────┘  └────────┘  └────────┘  └─────────┘
        │
   ┌────▼────────────────────────────┐
   │   Playwright Browser            │
   │  ┌──────────────────────────┐   │
   │  │   Strudel.cc Website     │   │
   │  │  ┌────────────────────┐  │   │
   │  │  │  CodeMirror Editor │  │   │
   │  │  └────────────────────┘  │   │
   │  │  ┌────────────────────┐  │   │
   │  │  │  Audio Context     │  │   │
   │  │  │  + Web Audio API   │  │   │
   │  │  └────────┬───────────┘  │   │
   │  └───────────┼──────────────┘   │
   └──────────────┼──────────────────┘
                  │
          ┌───────▼────────┐
          │ Audio Analyzer │
          │  - FFT Analysis│
          │  - Frequency   │
          │  - Spectral    │
          └────────────────┘

Core Components

1. EnhancedMCPServerFixed (src/server/EnhancedMCPServerFixed.ts)

Main MCP server implementation handling:

• 65 Tool Definitions: Complete API surface for music control
• Request Routing: Directs tool calls to appropriate handlers
• State Management: Tracks initialization, undo/redo stacks, pattern cache
• Error Handling: Graceful degradation and informative error messages
• Lazy Initialization: Browser starts only when needed

Key Features:

- Pattern caching before browser init
- Undo/redo stack management
- Session history tracking
- Generated pattern storage
- Safe fallback mechanisms

2. StrudelController (src/StrudelController.ts)

Browser automation layer using Playwright:

• Browser Management: Chromium instance lifecycle
• Editor Control: CodeMirror manipulation via DOM
• Playback Control: Keyboard shortcuts for play/stop
• Performance Optimizations:
  • Editor content caching (100ms TTL)
  • Direct CodeMirror API access
  • Resource blocking (images, fonts)
  • Fast DOM content loading

// Example: Optimized pattern writing
async writePattern(pattern: string) {
  await this.page.evaluate((newPattern) => {
    const editor = document.querySelector('.cm-content');
    const view = editor.__view;
    view.dispatch({
      changes: { from: 0, to: view.state.doc.length, insert: newPattern }
    });
  }, pattern);
}

3. AudioAnalyzer (src/AudioAnalyzer.ts)

Real-time audio analysis via Web Audio API injection:

• FFT Analysis: 1024-point FFT for spectral data
• Frequency Bands: Bass, low-mid, mid, high-mid, treble
• Analysis Caching: 50ms TTL for performance
• Features Extracted:
  • Average amplitude
  • Peak frequency
  • Spectral centroid
  • Playing state detection
  • Frequency distribution

Features provided:
- average: Overall amplitude (0-255)
- peak: Maximum amplitude
- peakFrequency: Dominant frequency in Hz
- bass/mid/treble: Band-specific amplitudes
- brightness: Timbral classification
- isPlaying: Boolean playback state

4. MusicTheory (src/services/MusicTheory.ts)

Music theory engine providing:

• 15+ Scales: Major, minor, modes, pentatonic, blues, whole-tone
• Chord Progressions: Pop, jazz, blues, rock, folk, EDM
• Euclidean Rhythms: Mathematical rhythm generation
• Arpeggio Generation: Multiple patterns (up, down, random)
• Note Transposition: Semitone-based pitch shifting

Supported scales:

major, minor, dorian, phrygian, lydian, mixolydian,
aeolian, locrian, pentatonic, blues, chromatic,
wholetone, harmonic_minor, melodic_minor

5. PatternGenerator (src/services/PatternGenerator.ts)

AI-powered pattern creation:

• Genre Templates: Techno, house, DnB, trap, ambient, jazz, intelligent_dnb, trip_hop, boom_bap
• Drum Patterns: 4 complexity levels per genre
• Basslines: 8 different styles
• Melody Generation: Scale-based with musical intervals
• Variations: Subtle, moderate, extreme, glitch, evolving
• Fills: 1-4 bar drum fills

Example generation:

generateCompletePattern('techno', 'C', 130)
→ Multi-layer pattern with drums, bass, chords, melody

6. PatternStore (src/PatternStore.ts)

Persistent pattern storage:

• JSON-based: Simple file storage
• Metadata: Name, tags, timestamp, audio features
• Tag Filtering: Organize by genre, mood, project
• Sorted Retrieval: Most recent first

Directory Structure

strudel-mcp-server/
├── src/
│   ├── server/
│   │   ├── EnhancedMCPServer.ts          # Original implementation
│   │   └── EnhancedMCPServerFixed.ts     # Production version
│   ├── services/
│   │   ├── MusicTheory.ts                # Theory engine
│   │   └── PatternGenerator.ts           # Pattern creation
│   ├── utils/
│   │   └── Logger.ts                     # Logging utility
│   ├── types/
│   │   └── index.ts                      # TypeScript types
│   ├── StrudelController.ts              # Browser automation
│   ├── AudioAnalyzer.ts                  # Audio analysis
│   ├── PatternStore.ts                   # Pattern persistence
│   └── index.ts                          # Entry point
├── tests/
│   ├── browser-test.js                   # Browser integration
│   ├── integration.test.js               # Integration tests
│   ├── manual-test.js                    # Manual testing
│   ├── mcp-tools.test.ts                 # MCP tool tests
│   └── strudel-integration.js            # Full integration
├── patterns/                             # Saved patterns
├── config.json                           # Server configuration
├── package.json                          # Dependencies
└── tsconfig.json                         # TypeScript config

Data Flow

1. Tool Invocation

   Claude → MCP Protocol → EnhancedMCPServerFixed

2. Pattern Generation (without browser)

   Server → PatternGenerator → MusicTheory → Pattern String

3. Pattern Execution (with browser)

   Server → StrudelController → Playwright → Strudel.cc

4. Audio Analysis

   Strudel.cc → Web Audio API → AudioAnalyzer → Feature Data

Performance Characteristics

| Operation | Latency | Notes | |-----------|---------|-------| | Pattern Generation | <100ms | Pure computation | | Browser Init | ~3s | One-time cost | | Pattern Write | ~50ms | With caching | | Play/Stop | ~100ms | Keyboard shortcuts | | Audio Analysis | ~20ms | With 50ms cache | | Pattern Save | ~10ms | File I/O |

Optimization Strategies

1. Caching

   • Editor content: 100ms TTL
   • Audio analysis: 50ms TTL
   • Generated patterns: Until browser init

2. Resource Blocking

   • Images, fonts, media blocked
   • Only load essential JavaScript/CSS

3. Direct API Access

   • CodeMirror view manipulation
   • Keyboard shortcuts over button clicks

4. Lazy Loading

   • Browser starts only when needed
   • Services initialized on-demand

🎹 Pattern Examples

Minimal Techno (Verified Working)

setcpm(130)
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)
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 strudel-mcp .

# Run container
docker run -it --rm strudel-mcp

# Or use docker-compose
docker-compose up

🔧 Development

Setup Development Environment

# Clone the repository
git clone https://github.com/williamzujkowski/strudel-mcp-server.git
cd strudel-mcp-server

# Install dependencies
npm install

# Install Playwright browsers
npx playwright install chromium

# Build the project
npm run build

Available Scripts

# Development mode with hot reload
npm run dev

# Build TypeScript to dist/
npm run build

# Start production server
npm start

# Run all tests
npm test

# Run integration tests with real browser
npm run test:integration

# Run browser-specific tests
npm run test:browser

# Validate MCP protocol compliance
npm run validate

# Lint code
npm run lint

# Format code
npm run format

# Clean build artifacts
npm clean

Publishing to npm

See NPM_PUBLISHING.md for complete publishing instructions.

Quick publish via GitHub Release:

npm version patch  # or minor, major
git push && git push --tags
gh release create v$(node -p "require('./package.json').version") --generate-notes

The package uses OIDC trusted publishing with provenance attestation for supply chain security.

Project Structure

src/
├── server/
│   ├── EnhancedMCPServer.ts          # Original implementation
│   └── EnhancedMCPServerFixed.ts     # Production version with caching
│
├── services/
│   ├── MusicTheory.ts                # Music theory engine
│   │   - 15+ scales (major, minor, modes, etc.)
│   │   - Chord progressions (jazz, pop, blues, etc.)
│   │   - Euclidean rhythm generation
│   │   - Arpeggio generation
│   │
│   └── PatternGenerator.ts           # Pattern creation service
│       - Genre-specific drum patterns
│       - Bassline generation
│       - Melody composition
│       - Pattern variations
│       - Complete track generation
│
├── utils/
│   ├── Logger.ts                     # Logging utility
│   ├── PerformanceMonitor.ts         # Performance tracking
│   ├── PatternValidator.ts           # Pattern syntax validation
│   └── ErrorRecovery.ts              # Error handling & recovery
│
├── types/
│   └── index.ts                      # TypeScript type definitions
│
├── StrudelController.ts              # Browser automation
│   - Chromium management via Playwright
│   - CodeMirror editor manipulation
│   - Playback control
│   - Pattern validation
│   - Error recovery
│
├── AudioAnalyzer.ts                  # Real-time audio analysis
│   - Web Audio API injection
│   - FFT spectral analysis
│   - Frequency band detection
│   - Playing state monitoring
│
├── PatternStore.ts                   # Pattern persistence
│   - JSON-based storage
│   - Tag-based organization
│   - Metadata tracking
│   - List caching
│
└── index.ts                          # Application entry point

Adding New Tools

To add a new MCP tool:

1. Define the tool in getTools() method:

{
  name: 'my_new_tool',
  description: 'Description of what it does',
  inputSchema: {
    type: 'object',
    properties: {
      param1: { type: 'string', description: 'Parameter description' },
      param2: { type: 'number', description: 'Numeric parameter' }
    },
    required: ['param1']
  }
}

2. Implement the handler in executeTool() switch statement:

case 'my_new_tool':
  // Your implementation here
  return await this.someService.doSomething(args.param1, args.param2);

3. Add necessary service methods if needed:

// In appropriate service file
async doSomething(param1: string, param2?: number): Promise<string> {
  // Implementation
  return `Result: ${param1}`;
}

4. Test the tool:

# Build
npm run build

# Test via MCP
echo '{"jsonrpc":"2.0","method":"tools/call","params":{"name":"my_new_tool","arguments":{"param1":"test"}},"id":2}' | node dist/index.js

Testing Strategy

1. Unit Tests

# Run with Jest
npm test

# Watch mode
npm run test:watch

2. Integration Tests

# Full integration with real browser
npm run test:integration

# This tests:
# - Browser initialization
# - Pattern generation
# - Audio analysis
# - Pattern storage
# - All 65 tools

3. Manual Testing

# Development mode
npm run dev

# In another terminal
claude mcp add strudel-dev node $(pwd)/dist/index.js
claude chat

# Then interact with Claude

Code Quality

TypeScript Configuration

// tsconfig.json
{
  "compilerOptions": {
    "strict": true,           // Strict type checking
    "esModuleInterop": true,  // Better module compatibility
    "target": "ES2020",       // Modern JavaScript
    "module": "ES2020",       // ES modules
    "moduleResolution": "node"
  }
}

Linting & Formatting

# ESLint
npm run lint

# Prettier
npm run format

# Pre-commit hooks recommended

Debugging

Enable Debug Logging

# Set DEBUG environment variable
DEBUG=strudel:* npm start

# Or specific modules
DEBUG=strudel:controller npm start
DEBUG=strudel:audio npm start

VS Code Launch Configuration

{
  "type": "node",
  "request": "launch",
  "name": "Debug MCP Server",
  "program": "${workspaceFolder}/dist/index.js",
  "preLaunchTask": "npm: build",
  "console": "integratedTerminal",
  "env": {
    "DEBUG": "strudel:*"
  }
}

Playwright Debugging

// In StrudelController.ts
this.browser = await chromium.launch({
  headless: false,  // See the browser
  devtools: true,   // Open DevTools
  slowMo: 100       // Slow down actions
});

Performance Monitoring

The server includes built-in performance monitoring:

// Access performance metrics
You: Show me performance metrics

Claude: Performance Report:
{
  "averageLatency": {
    "init": "3.2s",
    "write": "52ms",
    "play": "105ms",
    "analyze": "18ms"
  },
  "cacheHitRate": "85%",
  "totalOperations": 1247,
  "bottlenecks": [
    {"tool": "init", "avgTime": 3200, "calls": 1},
    {"tool": "write", "avgTime": 52, "calls": 156}
  ]
}

Contributing Guidelines

1. Fork the repository

   git clone https://github.com/YOUR_USERNAME/strudel-mcp-server.git

2. Create a feature branch

   git checkout -b feature/my-new-feature

3. Make your changes

   • Follow existing code style
   • Add tests for new features
   • Update documentation
   • Ensure all tests pass

4. Commit with meaningful messages

   git commit -m "feat: Add support for custom scale generation"

   Follow Conventional Commits:

   • feat: New feature
   • fix: Bug fix
   • docs: Documentation changes
   • refactor: Code refactoring
   • test: Adding tests
   • chore: Maintenance tasks

5. Push and create PR

   git push origin feature/my-new-feature

   Then create a Pull Request on GitHub with:

   • Clear description of changes
   • Link to related issues
   • Screenshots/examples if relevant

Release Process

# 1. Update version in package.json
npm version patch  # or minor/major

# 2. Update CHANGELOG.md
# Add entry for new version

# 3. Build and test
npm run build
npm test
npm run test:integration

# 4. Commit version bump
git add .
git commit -m "chore: Bump version to X.Y.Z"

# 5. Create git tag
git tag vX.Y.Z

# 6. Push to GitHub
git push origin main --tags

# 7. Publish to npm (if you have access)
npm publish --access public

# 8. Create GitHub release
gh release create vX.Y.Z --generate-notes

Docker Development

# Build development image
docker build -t strudel-mcp:dev .

# Run with volume mount for hot reload
docker run -it --rm \
  -v $(pwd)/src:/app/src \
  -v $(pwd)/patterns:/app/patterns \
  strudel-mcp:dev

# Run tests in container
docker run -it --rm strudel-mcp:dev npm test

Environment Variables

# Logging level
LOG_LEVEL=debug        # debug, info, warn, error

# Performance monitoring
ENABLE_PERF_MONITORING=true

# Pattern storage
PATTERNS_DIR=./patterns

# Browser configuration
HEADLESS=false
BROWSER_TIMEOUT=15000

# Audio analysis
FFT_SIZE=1024
SMOOTHING=0.8

📊 Performance

• Pattern Generation: <100ms
• Browser Initialization: ~3 seconds
• Pattern Writing: Instant
• Playback Start: ~500ms
• Audio Analysis: Real-time
• Memory Usage: <150MB

🎓 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 together

Headless 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 Sandboxing

• Playwright runs Chromium in sandbox mode
• No access to local filesystem from browser context
• Resource blocking prevents loading external content

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 chromium

Audio analysis returns "not connected"

Symptom: Audio analysis shows connected: false

Solutions:

1. Ensure pattern is playing first:

   You: Play the pattern, wait 2 seconds, then analyze

2. Reinitialize the browser:

   You: Stop, close the browser, reinitialize, and try again

3. Check 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 65 tools

# Reinstall MCP server in Claude
claude mcp remove strudel
claude mcp add strudel node $(pwd)/dist/index.js

# Restart Claude
claude chat

Performance issues / Slow response

Symptom: Operations take longer than expected

Solutions:

1. Enable caching (default, but verify):

   • Editor caching: 100ms TTL
   • Audio analysis: 50ms TTL

2. Use headless mode for faster operation:

   // config.json
   { "headless": true }

3. Batch operations:

   Instead of:
   - Add drums
   - Add bass
   - Add melody
   
   Do:
   - Generate complete pattern with drums, bass, and melody

4. Reduce browser overhead:

   • Close other browser instances
   • Disable browser DevTools
   • Use resource blocking (enabled by default)

Patterns not saving

Symptom: save command 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-deps

Linux

# Install system dependencies
sudo npx playwright install-deps chromium

# If running in Docker/headless environment:
# Ensure config.json has headless: true

Windows

# Use PowerShell or Git Bash
# Paths should use forward slashes in config.json

# If Chromium doesn't launch:
npx playwright install chromium

Debugging Tips

Enable Verbose Logging

# Set environment variable
DEBUG=* node dist/index.js

# Or in Claude:
You: Enable detailed logging for the next operation

Check 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: write_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:

1. Check existing issues: GitHub Issues
2. Run integration tests: npm run test:integration
3. Enable debug mode: DEBUG=* npm start
4. Consult Strudel docs: Strudel.cc documentation
5. Create new issue: Include error messages, OS, Node version, and steps to reproduce

🤝 Contributing

We need your help! This project is actively developed and welcomes contributions of all kinds:

Ways to Contribute

• Report Bugs: Found an issue? Open a bug report
• Suggest Features: Have ideas? Create a feature request
• Improve Docs: Fix typos, add examples, clarify confusing sections
• Write Tests: Help us reach 80% coverage (currently 78%)
• Fix Issues: Check open issues for bugs to fix
• Add Features: Implement new tools or improve existing ones

Quick Start for Contributors

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes and add tests
4. Ensure tests pass (npm test)
5. Commit with clear messages (git commit -m 'fix: resolve audio analysis bug')
6. Push to your fork (git push origin feature/amazing-feature)
7. Open a Pull Request

First time contributor? Look for issues labeled good-first-issue or help-wanted.

Feedback Welcome

• Questions? Open a Discussion
• Found something confusing? Tell us!
• Have a use case we haven't considered? Share it!

We review PRs promptly and welcome contributors of all skill levels. See DEVELOPMENT.md for detailed setup instructions.

📄 License

MIT License - see LICENSE file

🙏 Acknowledgments

• Strudel.cc - Amazing live coding environment
• TidalCycles - Pattern language inspiration
• Anthropic - Claude AI and MCP protocol
• Playwright - Reliable browser automation

v2.4.0 - Open Source | Experimental | Report Issues | Contribute

This project is under active development. Core features work, but expect bugs and breaking changes. Not recommended for production use.