Site quality lab
Site quality lab
Section titled “Site quality lab”Core Web Vitals, mobile heuristics, Lighthouse, and accessibility per URL/device.
HTTP response
Section titled “HTTP response”Code: HTTP_ERROR
Lab fetch HTTP status for the tested URL.
- Pass: Status below 400.
- Fail / warn: Client or server error during fetch.
Web Vitals
Section titled “Web Vitals”Cumulative Layout Shift (CLS)
Section titled “Cumulative Layout Shift (CLS)”Code: CLS_POOR
CLS measures visual stability; Google uses it in Core Web Vitals.
- Pass: CLS at or below 0.1 (good).
- Fail / warn: CLS above 0.1 — layout shifts hurt UX and CWV.
Largest Contentful Paint (LCP)
Section titled “Largest Contentful Paint (LCP)”Code: LCP_SLOW
LCP measures perceived load speed of main content.
- Pass: LCP at or below 2.5s.
- Fail / warn: LCP above 2.5s — optimize hero image, fonts, and server TTFB.
Mobile
Section titled “Mobile”Viewport meta
Section titled “Viewport meta”Code: MISSING_VIEWPORT
viewport meta tag is required for mobile-friendly rendering.
- Pass: Viewport meta present.
- Fail / warn: Missing viewport — mobile layout may break.
Horizontal scroll
Section titled “Horizontal scroll”Code: HORIZONTAL_SCROLL
Unexpected horizontal scroll indicates responsive layout issues.
- Pass: No horizontal overflow detected.
- Fail / warn: Page scrolls sideways on mobile viewport.
Readable text size
Section titled “Readable text size”Code: TEXT_TOO_SMALL
Tap targets and body text should be legible without zooming.
- Pass: No unreadably small text blocks.
- Fail / warn: Text too small on mobile — adjust CSS font sizes.
Tap target spacing
Section titled “Tap target spacing”Code: TAP_TARGETS
Interactive elements need adequate size and spacing on touch devices.
- Pass: Tap targets meet heuristic spacing.
- Fail / warn: Overlapping or tiny tap targets.
Lighthouse
Section titled “Lighthouse”Lighthouse performance
Section titled “Lighthouse performance”Code: LH_PERFORMANCE_LOW
Lab performance score from Lighthouse (0–100).
- Pass: Performance score at or above 50.
- Fail / warn: Low performance — review LCP, TBT, and asset weight.
Accessibility
Section titled “Accessibility”Critical accessibility
Section titled “Critical accessibility”Code: AXE_CRITICAL
axe-core critical violations block users of assistive tech.
- Pass: No critical axe violations.
- Fail / warn: Critical a11y issues — fix before release.
Page load
Section titled “Page load”Code: NAVIGATION_TIMEOUT
Playwright navigation completed within timeout.
- Pass: Page loaded in lab run.
- Fail / warn: Timeout or navigation error.