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Paste a URL and see the card Snapchat will build from it in chat.
Snapchat draws a link as a compact chat card: a rounded square thumbnail cropped from the Open Graph image on the left, with the title and the domain beside it. The description is dropped, so a card whose meaning lives in og:description reads as a small picture plus a headline here.
The tags it reads are the ordinary ones — og:title and og:image, with twitter:title and twitter:image as fallbacks. There is no Snapchat-specific namespace to set.
When chat shows a bare URL instead of a card, the fetch failed rather than the tag being absent. Snapchat's crawler needs to reach the page and the image without a login, without a long redirect chain, and without being served a different response by user agent. The scan above requests the page the same way, so a check that passes here is a fetch that works there.
An image that is missing, slow, or much larger than 1200×630 is the usual cause: the bubble has nothing to show, so only the link text remains.