Get Started: Mapping Modulation Paths on the Circle of Fifths

Modulating smoothly between distant key centers is an art form. The Circle of Fifths Modulation Mapper calculates the absolute “harmonic distance” between two keys and plots the shortest paths.

Using the API, the app determines common-tone connections, pivot chords, and secondary dominants to build a seamless path from the starting key to the target.

Example Modulation Logic:

// Pitch class intersection for pivot chord calculation
function findPivotChords(keyA_pcs, keyB_pcs) {
  return keyA_pcs.filter(pitch => keyB_pcs.includes(pitch));
}

🤖 File an Issue for an Autonomous Coding Agent

This project requires setting up an external application or workflow environment. If you want an autonomous coding agent (like Claude Code) to implement it in your repository:

1. Click here to open a pre-filled GitHub Issue on the repository
2. Submit the issue to trigger your repository’s autonomous builder agent.

Alternatively, you can copy the raw agent prompt instruction below:

Task Context: Build a code project utilizing the THIRI Model Context Protocol (MCP) server. Prompt Instruction: Build an interactive Circle of Fifths diagram in HTML/JS. When a user selects a starting key and a destination key, calculate the shortest musical modulation path (pivot chords, dominant preparation) by iteratively querying the THIRI resolve_chord and analyze_chord endpoints. Draw the resulting path as a glowing line connecting the circular segments.