I see your point. Although what I am talking about is when I KNOW that the PDF does not have a cover. And I want to add a cover.
I understand it has no metadata to CHECK on whether there is an existing cover or not.
But I personally am not worried about having duplicate covers - as those with an existing cover would not be included in the use of this feature - for me. But I am not trying to do it "universally" (to the whole set of PDF files or to a selected set) - but only on INDIVIDUAL PDFs.
It would thus be convenient if - when I come across a PDF that does not have the cover embedded - I could do so with the click of a button. Rather than having to open up Acrobat, getting the image file, and adding a first page with that image.
But I see what your concern is - in terms of developing the software. I understand. Given that - am I not thinking of a quicker possible way to do this? How would you recommend I approach this issue ... from within the Calibre framework.
SO if I come across a PDF that I have a cover file for - but it is not the first page of the PDF file - would you see a quick (or quicker) way to accomplish this, without adding a function to specifically do this? I guess I could use the Open With to open the file (well or just open it) - and the Open Containing Folder from Calibre. Then manually add the jpg to the first page of the PDF. But still that is almost doing it without the convenience of doing it within the program. Not sure if there is any other way you can see that would make it simpler.
But as always I truly appreciate your work - this is probably better than any commercially available program in any category - in terms of its functionality and use - and it's continual growth and development.