The Harmonic Tree is a real-time harmonic GPS that shows you possible chord progressions from your current musical context. Click any chord to explore where it can lead, building an interactive tree of harmonic possibilities. Each tile shows the chord name, Roman numeral with quality, and a score (0-127) indicating musical relevance — higher scores appear brighter.

Click anywhere on a tile (not on the buttons) to expand the tree, revealing possible next chords from that harmony. A colored arrow shows which tile was expanded. The display starts with your live playing context from the TMA on the left, with candidate tiles sorted by score to the right. Badges indicate diatonic chords (✓), modulations (🎯), and cadence targets (⭐).

Each tile has an 👂 ear button to audition the chord via MIDI without changing the TMA state, and an APPLY button to send the chord as a theory proposal to the live sequencer. The current card also features LOOP toggle, AUD PROG (play progression via MIDI), and PLAY PROG (send progression to TMA). A reset button clears all expansions.

The settings panel offers Adventure Level (0-10, higher = more remote modulations), Surprise Factor (adds randomness to scores), style weights for Jazz/Classical/Film, toggles for extended chords (9th, 11th, 13th) and substitutions (tritone subs, Neapolitan, augmented 6ths), Progression Speed slider, and transition type filters to focus on specific harmonic movements.

Composers can explore where a progression can go next. Educators can visualize harmonic relationships for students. Live performers can preview transitions without committing. Analysts can study relationships between modes and keys. The Harmonic Tree transforms music theory from a static reference into an interactive, living map.