J-6 Chords

A lightweight desktop GUI that reads live MIDI notes from a Roland J-6 (or any available MIDI input), detects chord names, and displays both the chord and pressed keys on a piano-style keyboard.

Features

• Auto-detects a MIDI input port (prefers names containing J-6/J6)
• Real-time chord detection from held pitch classes
• Displays:
  • detected chord name (for example: C maj7, D min9, G 13)
  • currently held note names (for example: C4 E4 G4)
  • an on-screen keyboard (range C3 to C5) with pressed-key highlighting
• Auto-reconnects when the MIDI device is disconnected/reconnected

Requirements

• Python 3.10+
• A MIDI input device (Roland J-6 recommended)
• OS MIDI support (CoreMIDI/ALSA/etc.)
• uv package manager

Setup (uv)

# install dependencies from pyproject.toml
uv sync

Run

uv run j6-chords-gui

Backward-compatible launcher still works:

uv run python j6_chord_gui.py

Build package

./scripts/build_package.sh

Build artifacts are written to dist/.

Publish

Automatic publish is handled by GitHub Actions on each published GitHub Release:

• Workflow: .github/workflows/publish-pypi.yml
• Details and credential checklist: PUBLISHING_TODO.md

Manual publish fallback (token-based):

PYPI_API_TOKEN=... ./scripts/publish_package.sh

File Overview

• pyproject.toml: project metadata, dependencies, and build configuration
• src/j6_chords/app.py: main application (MIDI input, chord detection, GUI rendering)
• j6_chord_gui.py: backward-compatible launcher
• scripts/build_package.sh: local build and package validation
• .github/workflows/publish-pypi.yml: CI build/publish workflow
• PUBLISHING_TODO.md: required credentials and where to configure them

Notes

• If multiple MIDI devices are connected, the app uses the first matching J-6 port; otherwise it falls back to the first available MIDI input.
• Chord naming is pattern-based and focuses on common qualities/extensions.