Get Blackbox Ledger

One page of the track record: the picks from N slate days (days that actually carry picks), most recent first, ending strictly before the request's cursor.

The window is counted in slates rather than calendar days on purpose. The panel commits nothing on a slate where every candidate collides with an earlier pick, and MLB has real off-days, so a calendar window goes thin exactly where the record is already sparse.

next_cursor is the oldest date on this page, and is exclusive: passing it back as before returns the page beneath this one. It is None once the record runs out.