Continuing the discussion from Custom visualization for specific attachment types:
Putting this out there as a feature request. I’d love to see the ability to onebox PDFs and other attachments along the lines of google docs oneboxing. Or perhaps even simply a file attachment appearance like you’d get using the file upload, ideally also with the file type and size provided.
Right now putting a PDF URL on its own line presents as a raw URL. Very 1990s. As my millenial colleague told me recently, “who needs to know what http is in this day and age?”