Use case or problem
For those that use a finite, predetermined list of tags, it would be useful to have the option to “lock” them, preventing the creation of new tags, say by typo or mislabeling–essentially forcing the use of predetermined tags.
Perhaps a toggle in options. It would have to be ‘off’ to add, modify or remove tags, then left ‘on’ to prevent changes. In the event an unlisted tag is created a warning could pop up, or the erroneous tag could be highlighted in some prominent way.
Current workaround (optional)
I have a note containing the tags I use which informs the auto-fill dropdown that appears when typing ‘#’. I typically arrow down and select from this list. Aside from that I review the tag pane occasionally for stray tags and manually change them. I use ATOM to find & replace when there are several.