Sometimes I forget to create a backup layer …
having glyphs automatically create one could be a useful feature (on change).
Behavior could include
If the last change is older than X, duplicate the current master layer.
Possibly auto-delete the oldest history layer
and keep N amount of history layers
Checking the last backup every time you do an edit and add a new one will be slow and quite intrusive. And should it be done for ever small change (e.g. spacing) (probably not)? But how to decide what is a “meaningful” change?
That sounds more like you should use git or something.