seo-core-web-vitalslisted

Audit Core Web Vitals & page performance — measure LCP, INP, and CLS against p75 field thresholds, diagnose render-blocking resources, unoptimized images, and layout-shift sources, and produce prioritized, advisory-only remediation guidance. Module M15. Feeds the Search SEO score (heavily) and the AI Visibility score (minimally).
Hainrixz/claude-seo-ai · ★ 14 · Web & Frontend · score 81

Install: claude install-skill Hainrixz/claude-seo-ai

# seo-core-web-vitals (M15) Core Web Vitals are a confirmed Google ranking signal and a proxy for page quality. Thresholds, field-vs-lab honesty rules, and LCP decomposition: `references/cwv-thresholds.md` (follow it exactly). ## Audits Working from the PageSnapshot (`rendered_dom` if present, else `raw_html`): 1. **Field CWV at p75** — LCP ≤ 2.5 s, INP ≤ 200 ms (INP replaced FID), CLS ≤ 0.1, all at the 75th percentile of real-user data. All three must pass for a "good" rating. Use the proactive-warning thresholds (LCP > 2.0 s, INP > 160 ms, CLS > 0.08) to `warn` before failing. 2. **Render-blocking resources** — synchronous `<script>` in `<head>` (no `defer`/`async`/`type=module`), blocking `<link rel="stylesheet">`, and `@import` chains that delay first render (LCP/INP risk). 3. **Unoptimized images** — missing `width`/`height` (or `aspect-ratio`), no `loading="lazy"` below the fold, no responsive `srcset`/`sizes`, legacy formats where AVIF/WebP would serve, and a non-preloaded LCP image. 4. **Layout-shift sources** — images/iframes/ads/embeds without reserved dimensions, web-font swap without `font-display`/size-adjust, and content injected above existing content (CLS risk). 5. **LCP decomposition** — attribute LCP to TTFB vs resource load delay vs load duration vs render delay (see `references/cwv-thresholds.md`) so each finding targets the dominant subpart. ## Fixes (fixable: advisory) **Advisory only.** Performance fixes touch build config, server, CDN, and runtime J