Resource check & browser check
A 200 status code doesn't mean the page actually works: scripts can 404, the CDN can be down, JS can throw, APIs can keep returning 500. Two checks cover these cases; both are triggered manually from the site detail page and results are archived for review.
#Resource check
Without executing JS, it requests every script/style/image the page references and lists the resources that failed to load with their response times.
#Browser check
Opens the page in real Chromium and collects: console.error, uncaught page exceptions, failed network requests / abnormal API responses, CORS and CSP blocks. Each run takes a few to a dozen seconds — a heavyweight check, not part of the high-frequency loop.
Browser checks run "once per round"; alerting is based on sustained failure counts so an occasional flapping blip won't spam you. They're resource-intensive — don't set them too frequent.
Related: Content watch · Site detail page