seo-rendering (M4)

Most AI crawlers do not execute JavaScript, so content that only exists after hydration is invisible to them — CSR-only is a hard AI gate. JS dependency also delays first paint; see references/cwv-thresholds.md for how this feeds LCP/INP.

Audits

Working from the PageSnapshot (rendered_dom if present, else raw_html) and the raw HTML the server first returned:

1. Content delta: diff raw_html vs rendered_dom — measure the share of primary text, internal links, headings (h1–h3), and <script type="application/ld+json"> blocks that appear only after JavaScript runs.
2. Classify the strategy: CSR-only (empty/near-empty raw shell, content injected client-side) / SSR / SSG (prerendered static) / ISR (prerendered + revalidated). Use raw-HTML completeness and framework signals (__NEXT_DATA__, hydration markers, data-reactroot, build manifests).
3. Hydration-blocked text: primary content present in raw HTML but hidden/empty until hydration, or rendered only into a client-only island.
4. Lazy-loaded main content: above-the-fold or primary content that requires scroll/intersection/interaction to load — invisible to a non-interacting crawler.
5. AI gate: if the h1, primary body, or JSON-LD exist only in rendered_dom, flag the page as not reliably consumable by non-JS AI crawlers.

Fixes (fixable: advisory)

Rendering strategy is a framework/architecture decision with high breakage risk, so M4 is ADVISORY only — it diagnoses and prioritizes, it never auto-edits build/server code.

• Emit framework-specific guidance: e.g. move CSR-only routes to SSG/ISR or SSR (Next.js App Router server components / generateStaticParams + revalidate; Nuxt/Astro/SvelteKit equivalents).
• Recommend prerendering or partial prerendering for primary content; reserve client-only islands for genuinely interactive widgets.
• Where the right strategy depends on data freshness or constraints the snapshot can't reveal, leave a clearly-marked TODO for the user — never fabricate a revalidate interval or assert a strategy choice. Every finding carries fixable: advisory.