What is a long-term spy called in espionage jargon?

A "sleeper" is what I thought. A "mole" is someone, as Kris says infiltrates, doesn't need to be long term. There are also long term spies, "handlers", who are not moles, they communicate. This is all fiction writing I am writing about. I never know, whether le Carré, cold war, or modern. The truth????

Well, I suppose it's a good name as it refers to creatures who live underground for years and are never really seen

Holy Moley we don’t like Moles! Unless of course they’re on our side! 😬