setShuffle

Plays the queue in a shuffled order, or puts it back in the order it was given.

Shuffle is an order OVER the queue, not a reorder OF it. The items in PlayerSnapshot.queue never move, so the list an application shows stays the list someone built, and turning shuffle off needs nothing put back. What moves is PlayerSnapshot.queueOrder, which next, previous and the advance at the end of an item all follow.

Turning it on leaves the item that is playing playing, and makes it first in the new order. An item added later joins the order somewhere after the one playing rather than always last. seed makes the order reproducible, which is what a test or a shared session needs.