replay sends the held request from the worker to its own URL with no cookies, so identity
has to be in the payload. sink hands it to the server half in the flush, for a vendor that
needs a secret the page must not hold.
the origin and path prefix of the collector's URL, such as https://www.google-analytics.com/g/collect
the vendor's backfill window less a margin, in milliseconds
Optionalstampa query parameter the replay sets to the event's time, for a vendor that accepts one
names the collector in drop counts and on the held event
A cross-origin analytics collector the worker holds instead of letting the page send it. The page gets an immediate empty answer; the event leaves on a network moment that happens anyway, inside
maxAgeMs. Events older than that are dropped and counted, never sent late.