# Requirement change

Management is unhappy that an agent who was excellent two years ago and has coasted ever since
still tops the leaderboard. They want a version of the leaderboard that only looks at recent
behaviour: give me the ranking using only ratings from the last so-many days, counting back from
right now.

The number of days should be something I can pass in each time I ask, not something fixed once and
forgotten — one team might want the last 30 days, another the last 90. A rating that is exactly on
the edge of the window (say I ask for the last 30 days and a rating is from exactly 30 days ago)
should count as inside the window, not outside it.

The existing leaderboard — the one that has always looked at an agent's whole history — doesn't
change and keeps working exactly as it does today. This is a second, separate way to ask the same
kind of question, not a replacement. Same scale, same tie-break rule, same rounding, same
everything else — just a different slice of the ratings feeding into it.

Asking for zero days, or a negative number of days, doesn't mean anything and should be refused
rather than silently treated as "everything" or "nothing".
