Some editors will save file change history off in a different/configured directory. I'm not talking about just changes for currently open files, I'm talking about log out, come back days later, open the editor and be able to return to a file from 20-30 saves ago. On another mailing list someone mentioned a plug-in for Eclipse doing this. I seem to remember UltraEdit had something similar (just a really bad C/C++ coding template).

I originally came from the VMS world where this was a file system feature. Any time you saved a file it created a new version. We could have versions 1 - 32767 with the newer versions having the higher numbers.

Is there a plug-in or something which will let you configure a location and depth for file change history?

I'm not talking about checking into Git or some other version control system. SlickEdit calls this "Backup History" https://www.slickedit.com/products/slickedit/cool-features#h-files-editing. Originally coming from VMS I call it file versioning. I couldn't find it mentioned in the features list for KDevelop but I could be blind.

Nothing like that is provided by KDevelop itself or any 3rd party tool I know off.

However, I think I remember some tooling around git which provides similar functionality, i.e. automatically creating commits when files change or after a certain time. I don't have anything specific in mind though, you'd have to look around.