Snapshot of per-model calibration state, in insertion order.
Record one completed call: the request as estimated, and the
provider-reported actual usage. Wire this to the bulkhead's
release event: on("release", (e) => { if (e.usage) observe(e.request, e.usage) }).
Observations with a zero base input estimate are ignored (no ratio
can be formed). Throws if usage fields are not non-negative
integers.
Clear calibration for one model, or for all when omitted.
Optionalmodel: string
The estimator to pass as
tokenBudget.estimator.