this is a throwaway post for previewing link hover cards. every external markdown link gets one automatically when the target exposes metadata. hover over any link below.
wikipedia links
wikipedia urls are special-cased through the rest summary api, which gives a cleaner extract than their open graph tags. minimizing KL divergence is equivalent to maximum likelihood estimation, and entropy gives it a natural unit.
thumbnail layouts
a landscape thumbnail renders as a banner across the top of the card, like the golden gate bridge. a portrait thumbnail sits beside the extract instead, like alan turing.
other websites
any other site works through open graph metadata. try the attention paper, next.js on github, or transformer circuits.
fallback
a link whose page does not resolve, or exposes no usable metadata, degrades to a plain external link with no card: this one.