StreamTapePolicy

the sub-stream index at which the tape begins; defaults to 0. Concurrent solver execution (e.g. parallel random restarts) gives each member its own policy starting at a distinct block offset (member index times a generous block size) so members draw from non-overlapping regions of the sub-stream tape regardless of scheduling. Sub-stream positioning is a constant-time jump, so large offsets cost nothing. Must be non-negative.