A benchmark that does not go stale. New records arrive every quarter, so the held-out set moves with the world.
Withheld by construction
The held-out slice is carved before any training delivery is cut, per company and per task family, and its hashes are recorded so contamination is checkable rather than asserted.
Same verifiers
Scored by the graders the environment ships with, against what the outside world said happened.
Human baseline
Where the original staff worked the tasks, their pass rate is reported beside the model's.
Reported per task family
Pass rate, partial credit where the rubric allows it, and the distribution of failure modes, so a lab sees where a model breaks rather than a single number.
Refreshed
New held-out slices as new records arrive. A benchmark that was current a year ago is still current.
Custom slices
Held-out sets built to a lab's specification on a shared corpus, or on an exclusively licensed one.