Two chords that never resolve — i-7 to IV⁷ (Dorian), or 1 to ♭7 (Mixolydian).
the mode the vamp spells — target its SIGNATURE note — SCL·06
land on the note that names the mode (Dorian's ♮6, Mixolydian's ♭7) and the color pops KC·29
A vamp has no cadence to argue with, so a mode can just BE — this is where modes are most audible. The IV⁷ (not iv) is what makes it Dorian, not plain minor.