Hi, I would like to thank you first for your work on this program, it works fine as is.
The 2 improvements I think would help and expand it and attract more users are:

1 Use 'Incomplete' folder for incoming downloads, and then use a MOVE/Delete to a 'Complete' folder.  This would eliminate the current fragmentation problem (mostly) and allow the 'Complete' folder to be a large library folder on another drive.
The move/delete makes the files un-fragmented (usually), and would allow a larger drive to be used for completed files so more files would be available, and they would be stable.
I find that currently I need to download multiple sets as users come and go in order to finish a set download, otherwise they just sit there taking space.

2. Being able to add folders to the library would allow more files to be available and make the files more stable.

I currently use a 3 disk raid 0 ssd set for Fopnu downloads, 1 tb available.  I can get by with a weekly defrag because I move the completed files to a 32tb raid 0 drive (backed up of course), but these moved files are no longer available to Fopnu.
I then need to select the shared files and copy them back to the 1 tb ssd. Many downloads end up not being shared simply because there is not enough room. I would not grind 32tb platters with Fopnu download fragmentation.
The fragmentation no longer matters if the files are moved or copy delete action.

If your source code is the same as tixati you should have a step up on the coding...
I don't think it would be that difficult of a change, especially if the library folder consisted of just the 'Incomplete' and 'Completed' folders.
In my case 32tb of stable files would be available instead of 1tb of unstable files in the process of being downloaded, and a select few in my 'Done' folder on the ssd.

Again thank you for your work and please keep up the support.

David
User MoveToDone
PS: I get 1100MBs r/w out of the 3 ssd raid 0 (nearly as fast as my nvme), and 550/600MBs out of a 4 disk 32tb raid 0. 10gbe to the backup drives so the raid is the slowest part.
Stuck with win10 because the linux flavors I've tried will not 'see' my 3rd SAS controller... (linux mint is my preference, multi-boot to about a dozen or so operating systems)

Maybe I'm misunderstanding but #2 sounds like you think only the Downloads folder is shared in Fopnu. You should click on the Library tab and then the +Add button in the upper left, you can add any folder or drive you want. I don't even share my active downloads folder because I don't want people to see incomplete files.