Give someone a chance to agree before treating their cooperation as settled.

Assumed agreement is not agreement. When a plan is announced rather than proposed, the other person is left to comply or make a scene, and most people comply and quietly resent it. Their cooperation then looks willing while being nothing of the sort. A real yes needs a real chance to say no.

Ask before you announce, even when you are almost certain of the answer. Leave a pause after the question so the other person has room to use it.