bluesky's link-unfurl proxy (cardyb) reads <link rel="site.standard.publication" href="at://..."> to render a rich publication embed. zat.dev is a registered site.standard.publication but wasn't emitting the tag, so pasted links got no preview. add the link-rel (mirroring leaflet's output) plus a basic OG/twitter card block for clients without standard.site support. note: SPA serves one index.html for all routes, so this covers the publication homepage; per-document previews would need SSR/per-route tags. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>