Frontend Observability
Errors, failed requests, vitals and interaction latency from real users on real devices — and the privacy obligations that come attached to every one of them.
Capturing exceptions and unhandled rejections with enough context to act on — the route, the release, the breadcrumbs — and separating real signal from extensions, bots and opaque cross-origin noise.
Field measurement from the machines your users actually own — how it differs from synthetic testing, why the two disagree, how to sample, and why watching the median hides the problem.
Loading, interaction responsiveness and visual stability measured on real devices — what each observer actually records, why field values differ from lab values by design, and why the boundaries are not yours to memorise.
Requests that never arrived, timeouts, DNS and TLS failures, opaque CORS errors, offline users and navigations that cancel in flight — the failures with a zero server error rate.
Replay records whatever was on the screen — including things you did not intend to record. Masking is opt-out shaped and fails open, so the governance question comes before the engineering one.
Attributing a regression to a deploy when clients update on their own schedule: tagging every signal with a release, reading the adoption curve, and comparing cohorts instead of time windows.