I use Syncthing to automatically copy newly added music and book files from folders on my main PC to my phone and tablet. The folders on the main PC are send-only and on the phone & tablet receive-only as the PC is the only place I add new media and the phone/tablet are only for consumption. This all works as expected.
The problem is the files which have already been copied over are being repeatedly resynced again from the PC on subsequent days. I think this is because the player and reader apps on the phone/tablet are updating embedded metadata like play count and read position in the media files, which changes the file modified date (and maybe file size). I don’t want the play count or read position metadata to be reverted back to the PC’s version. I just want any newly added files on the PC which don’t yet exist on the devices to be automatically copied over once but then ignored once the filenames already exist.
I’ve looked at the Syncthing docs but haven’t found how to do this. Being so flexible I assume SyncThing can do this but suspect I must be missing something obvious.