Conflicting Edits

It’s really annoying to try and add tags and find that you’ve just deleted every tag someone else added. Is there any way to merge edits?

Yes, yes it is extremely annoying. Currently that’s just how the system works; you push your entire tagset through to the system, rather than just the additions or substractions.
 
There is a plan to make it so you won’t delete tags that weren’t there when you open an image (ie tags someone added while you were adding yours), but I can’t give any estimates on when.
 
But trust me, we’re very well aware that this is an issue.

This is something bugging me for a while, so I’ll go ahead and nip it in the bud, soon, either before or after Clover finishes refactoring the ImagesController code (in which it resides).