Power adapter on the laptop?

I would be interested in whether I can leave my power supply in the laptop all the time even when it is not charging? Quasi leave the power supply in the laptop but not plugged into the socket

I would also be interested in that, I'm not sure, but I think that harms the battery a bit but not that bad

It makes no difference whether the power adapter is connected to the laptop when it is not plugged in. Diodes are built into the interior to prevent the current from "flowing back".