When someone shares a URL in a Google Chat message, Google’s user-triggered fetcher crawls the page to generate a link unfurl card. This fetcher operates on behalf of the user who shared the link, ignores robots.txt directives, and does not execute JavaScript. It reads standard Open Graph meta tags to build the preview.
This guide covers how Google Chat’s fetcher works, which tags it reads, image handling, cache behavior, and common issues – including enterprise admin controls that can disable previews entirely.