No version constant in the script, no ETag, 1-hour cache with no purge or ?v= convention — support cannot tell which tracker a site runs; fixes roll out by cache expiry. Fix: embed a build version, send it on beacons, aggregate server-side; ETag on jsResponse; document ?v= cache-busting.
From the production-readiness audit (docs/research/production-readiness.md, eacf996). Verified with live probes where stated.