$engine
$engine : \Drupal\strata\Engine
Writes this request's store traffic into the per-day record once the response is out.
Terminate rather than response: the write is bookkeeping and the visitor should not wait on it. A request that never touched the store leaves an empty accumulator and costs no query, so the subscriber is registered unconditionally.
A failure here is logged and swallowed. Losing a day's request count is a gap in a cost report; letting the same failure out of a terminate listener would be a fatal on a page that has already been sent.
$engine : \Drupal\strata\Engine