F19.3 — Indexability review and performance

[jbourdin]

Summary

Remaining indexability and crawl-performance items not covered by the F18 SEO foundation. Hreflang (F18.26), JSON-LD (F18.27), Open Graph (F18.28), dynamic sitemap (F18.23), and robots.txt (F18.24) are already shipped.

Remaining scope

Pagination SEO

• Add <link rel="prev"> / <link rel="next"> to paginated public listings (events list, decks list, archetypes list, CMS pages list).

Soft-deleted content → 404

• Audit public detail routes (deck, event, archetype, page) and confirm soft-deleted entities return HTTP 404 (not 200 with an empty page or 500).

Crawler performance

• Review TTFB on key public pages (homepage, listing pages, top archetype/deck/event detail pages); target <500 ms.
• Spot-check listing pages for N+1 queries (Symfony profiler).
• Consider HTTP cache headers (Cache-Control, ETag) on public HTML responses for CDN/proxy caching, beyond the existing sitemap cache.

Social sharing validation

• Verify OG previews on Facebook, Twitter/X, LinkedIn, Discord.
• Confirm og:image dimensions ≥ 1200×630 (or that the fallback meets that).

Acceptance Criteria

• Paginated listings include rel="prev"/rel="next".
• Soft-deleted content returns 404 across all public detail routes.
• Key public pages have acceptable TTFB (<500 ms) and no N+1 on listings.
• HTTP cache headers reviewed (and added where appropriate) on public HTML pages.
• Social sharing previews render correctly on the major platforms.

Out of scope (already done)

• Hreflang alternates — F18.26
• Canonical URLs — already in templates
• JSON-LD structured data — F18.27
• Open Graph / Twitter Card — F18.28
• XML sitemap and robots.txt — F18.23 / F18.24