Please allow low-occurence tags to be declared persistent

Question

Single-use tags are pruned after six months. Sometimes, this removes spurious tags. Sometimes, this removes legitimate tags.

After a quick look on Unix SE, I see plenty of legitimate tags that are at risk. I would like a way to declare that some tags are legitimate and should never be pruned. This could be a 10k tool, for instance.

I realize this might not scale on Stack Overflow, but it would work for smaller sites (I'm using Unix as an example because it's the one I know best). A warning when tags are about to expire would be a helpful complement.

Answer 1

Tags that have a tag wiki no longer expire even if they are only applied to one question. Therefore, you can vet a tag by writing a tag wiki for it.

Answer 2

Another idea is to delete a low occurence tag, say, two times. If the tag reappears after that it's permanent.

Answer 3

If you have enough knowledge about the tag to know that it should stay, it's not hard to come up with a suitable question that uses it.

Post such a question, use the tag, and the problem goes away - the tag stays.