How are actions NOT within the client's visibility radius emulated in games?

Question

Game development

Hello, just out of curiosity, I have a question. There is a server there is a client
For example, the client has a visibility radius of 200 game meters.
The server will spawn an AI that is NOT within the radius of this client (accordingly, it makes no sense to load this AI in the player's client), this NPC must do certain actions, for example, walk from point A to B.
If the AI ​​falls within the radius of visibility, it must be loaded from the client, and be at that intermediate place from point A to B (to where it should have reached, from the moment it was spawned by the server)
Loading into the client is even less clear, but how the action should be emulated if there is not a single client within the AI ​​radius, where should it load?

Answer 1

AI operates on the server. And there he lives. It seems to be the same client in fact.

Answer 2

Why would an NPC be loaded onto a client at all?
He does all the actions on the server anyway. walks (changes coordinates), interacts with others (sells, that is, moves data), fights (health or mana decreases), dies (object is removed from server memory).
And on the client it's all just rendered for video.

Answer 3

In Arma 2 and Arma 3, the server also processes the client side of the program without drawing graphics. And the result of her work broadcasts to all clients.