How to display book cover?

Sorry, just found the “Set image” button in the Browse tab.
Nevertheless, would be fine to get one from Zotero itself.

Not sure what you mean — “from Zotero itself”?

I mean adding the cover picture in Zotero (standalone for instance).
At first, I followed this discussion in the Zotero forum: https://forums.zotero.org/discussion/433/how-to-add-a-picture-book-cover-to-a-book-entry
But the tip given by noksagt did not work, i.e. the cover did not display when using Zotpress.

Oh yes. This is adding an image (of the cover, or anything else) as an attachment. But I don’t think it’s signified as particular kind of image, e.g., as a cover photo, in the meta information, so I can’t program Zotpress to “see” it …

Even if the filename is cover.jpg or with a “cover” tag?

There’s many possibilities such as what you suggest but no standard way. Additionally, looking up attachments is another request per item, which slows things down. I foresee too many issues right now. I wonder if Zotero would be open to adding a “cover” meta option.

Yes, I understand your point of view.
Many thanks for your time and answers.