I had a thought on chord and note handling that would preserve chord progressions and melodies across all possible scales:   In 7 note scales, there are predictable basic chord shapes - there is a i, ii, iii, iv, v, vi, and vii chord - in a major scale, these are maj, min, min, maj, maj, min, diminished - in a minor scale they are min, diminished, maj, min, min, maj and maj.  These chords are easy to find from the notes in the scale - simply take the root note of the chord, and add the notes t