Web Quality Audit

# Web quality audit

Comprehensive quality review based on Google Lighthouse audits. Covers Performance, Accessibility, SEO, and Best Practices across 150+ checks.

> **Lighthouse v13 note (Oct 2025+).** Lighthouse has migrated the Performance category from per-opportunity audits to **Performance Insight Audits** ([announcement](https://developer.chrome.com/blog/moving-lighthouse-to-insights)). Several individual audit names this skill historically referenced — *First Meaningful Paint*, *No Document Write*, *Uses Passive Event Listeners*, *Uses Rel Preload* — have been removed or merged. The underlying *advice* is unchanged and still applies; only the report format moved. The CLS-related audits ("layout shifts", "non-composited animations", "unsized images") are now consolidated into a single `cls-culprits-insight`, and image audits are merged into `image-delivery-insight`. Treat older Lighthouse JSON output as a superset, not a contradiction.

## How it works

1. Analyze the provided code/project for quality issues
2. Categorize findings by severity (Critical, High, Medium, Low)
3. Provide specific, actionable recommendations
4. Include code examples for fixes

## Audit categories

### Performance (40% of typical issues)

**Core Web Vitals** — Must pass for good page experience:
* **LCP (Largest Contentful Paint) < 2.5s.** The largest visible element must render quickly. Optimize images, fonts, and server response time.
* **INP (Interaction to Next Paint) < 200ms.** User interactions must feel instant. Reduce JavaScript execution time and break up long tasks.
* **CLS (Cumulative Layout Shift) < 0.1.** Content must not jump around. Set explicit dimensions on images, embeds, and ads.

**Resource Optimization:**
* **Compress images.** Use WebP/AVIF with fallbacks. Serve correctly sized images via `srcset`.
* **Minimize JavaScript.** Remove unused code. Use code splitting. Defer non-critical scripts.