This is response time — the moment the answer starts arriving — and nothing else. Not Core Web Vitals, not a Lighthouse score, not a page-load graph. One number, written as a check, verified every time the check runs.
No card. Five monitors on the free plan.
time < 800ms in {page}
The problem
A line on a dashboard is not a question, and a graph cannot fail. Write the number as a check instead: it passes or fails like every other check you have, it fails the day the page gets slower rather than the week somebody opens the dashboard, and it reads a year later as what you meant.
time < 800ms in {page} — the number from the ticket, written
where the rest of your checks live.
run rule "expect-response-time" in {page} < 800ms — one line in
a script that runs on a schedule and carries its evidence.
time < 800 is refused. A bare number would quietly mean milliseconds,
and a check that guesses at what you meant is worse than no check.
The evidence
The verdict carries the number it measured and the number you asked for, in the same units, on both sides.
answered in 49ms — wanted < 1ms
And two it refuses to answer, in its own words — a tool that says no clearly is making a claim about the yeses:
time < 800
→ `time` compares a duration — write the unit, e.g. time < 800ms (or 2s)
time < 800ms in {page} with mode=browser
→ `time` is a response time, and browser mode measures page-load
The boundary
Said plainly, because this audience knows the difference and will not forgive a page that blurs it.
Questions
Short answers, and no for the ones that are no.
No. It is one number: the response time of the page’s fetch, measured from request sent to headers arrived. LCP, CLS and INP are not measured, and this page will not imply they are.
The prober that runs your checks. One number from one place — not a field of real users, and not a lab profile.
Because time < 800 has two readings and only one of them is yours. A
check that guesses is worse than no check, so the language asks rather than assumes.
No, deliberately. Browser mode measures navigation, which is a different quantity, so the check refuses by name instead of answering with the wrong number.
The same thing that happens when any check fails: a failing verdict with its evidence, and an alert if you wired one — e-mail on any plan, webhook, Slack or Discord on the paid plans.