Correct me if I’m wrong, but Rocket.Chat Community Edition currently does not support in-browser preview of PDF files uploaded to its servers. While images can be previewed directly within the chat interface, PDF and other document types require either downloading or opening externally. This limitation arises because Rocket.Chat’s preview feature (chat.getURLPreview) only fetches metadata and does not stream file content. As a result, users often need to download files to view them, which can interrupt workflow and reduce user experience.
I presume this is you as well?
Please use one topic in one place rather than trying everywhere to get attention. It is hard to follow & gets confusing.
Read all bugs including closed ones before you start.
It’s not just CE but all versions.
The pdf library was removed years ago as it was big, cumbersome & flaky IIRC. I doubt they’ll restore it in core.
Your best bet is to ask on open.rocket.chat in the gsoc channels, and look at writing an app.