4. Mix
A Mix combines a tracklist with the exact planning choices used to create it. The track order, locks, exclusions, target track count, BPM, group scope, key profile, transition profile, loudness target, and other Mix Settings travel together.
Harmonic DJ ranks complete routes by improving the weakest accepted transition first. This keeps several strong transitions from averaging away one poor connection. Your personal track ratings then provide a bounded preference among eligible choices without weakening the Mix constraints.