Neither. Reality works based on cause and effect.
In order for there to be pre-determination there needs to be a determination point (creator or point of origin) which in Buddhism does not exist.
In order for there to be complete free will there needs to be an independent self that makes independent decisions not conditioned by external factors which in Buddhism does not exist.
Reality is a series of conditioned moments of experience. Arising and passing away constantly without a controller or creator. With no point of origin and without independent decision making.
Intention or will arises based on causes and conditions just like every other experience. I hope this helps.