I could only second my opinion about that. And would add that’s I’m personally would not bother with a Attachment concept. Or see the attachment as reference to a doc repository. which evn cold be local to fibery.io and created as part of “the uploading” but from there it should be treated as a file repository with all metadata attached to it.
Something mire was described here: [TO IMPLEMENT] Drag PDF to wiki fails to produce a preview - #9 by Holger_Winkelmann
tl,dr; I would see fibery.io not as a content store rather a cross-index to Information to, or better inside of documents.