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A favorite outlives its thumbnail. Sources sign their CDN paths and the signature expires, so a video kept months ago has a `thumb` that 404s and a card that is a grey box with a title under it. Asking the source page for a fresh picture covers the case where the page still exists; nothing covered the case where it doesn't. The video does, because playback re-resolves from the page URL every time. So once every route to the listed picture is exhausted, a frame a quarter of the way in becomes the card's picture -- past the black lead-in, and a fair guess at what the video looks like. It goes through our own proxy, so the canvas can be read back, is scaled to card width and JPEG'd to a handful of KB, and is kept: later mounts and later sessions paint it without a request, instead of asking again for a picture that is known to be gone. Only for favorites, once per item, one at a time, and never for a live stream or a manifest. Two things worth knowing, both found with the browser rather than reasoned about: a browser fires `seeked` for its own initial seek to zero, so taking the frame on the first one captures the opening of every video; and the same item is on screen in more than one place, so the captures are deduped by a promise rather than the first asker getting the picture and the rest being told there isn't one. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01MPZFnNdHbPGDTqQUNiE4ZN