Ring Arc

A chord as a thick band over a ring of notes (a key's seven in line-of-thirds order, so stacked thirds are neighbours), with the chord before it as a ghost band on an outer track and the next on an inner one. Notes read in one colour language: shared notes solid and tied radially to the ghost track, arriving notes in the accent, leaving notes dashed, and the shared count in the centre. Editable: drag the band to move the chord, drag an end knob to widen or narrow it (triad, seventh, ninth), tap a note to toggle it, with keyboard equivalents. An optional outer ring of real note names with semitone ticks turns to transpose.