Shared links now unfurl with an image in WhatsApp, Telegram and anything
else that reads Open Graph, instead of showing the bare URL.
A dedicated og/ rendition is generated per photo: 1200px longest side,
quality laddered down until it fits under ~250 KB. WhatsApp drops the
preview entirely once the image passes ~300 KB, and the medium rendition
can exceed that, so it is not reused. Dimensions for og:image:width and
og:image:height are read back from the encoded file with DecodeConfig, so
they are emitted even when the rendition itself was skipped as up to date.
The og:image and og:url values are absolute via BaseURL; both crawlers
ignore relative image paths. Previews therefore only work against the
deployed base URL, not http://localhost.
puttaalu
d4fec5b0ff