fn folded(frames: Vec<SeatUpdate>) -> Vec<(SeatUpdate, u64)>Expand description
The run of frames as the client reads them: the token appends folded into the one frame they draw as, each survivor carrying how many of the seat’s numbers it stands for.
The span is what keeps a folded run from reading as a gap. The numbers of the frames the fold took are still consumed - nothing re-numbers a stream - so a client told only the survivor’s own would ask for frames it had already drawn.