flying tacklehugs

My kid is very sweet, and he is a hugger. Boy howdy. We're talking to him a lot lately about making sure people want hugs and are ready for them, because other people's bodily autonomy is a thing, so he is instructed to ask his teachers (e.g.) and his friends if he can hug them, and if they say anything south of "Sure!" he is to take no for an answer. He's pretty good about this at school.

At home, less so. His dad and I always ask before we hug him, but he's about 50/50 on asking before he glomps onto us, and even when I've held out my arms and invited the hug and know it's coming, some of the time he just flings his little body at me - on a jump, which means, if I was sitting down when he came at me, his shoulder collides with my chin and one of these days one of us (me!) is going to get badly hurt. So far it hasn't been worse than clanging my teeth together, knocking my head back in a jarring blow to the back of the neck, and biting my tongue. And he's very appropriately and sincerely contrite when this happens. But if he doesn't learn to remember that he's getting bigger, it's going to get worse before it gets better. (His dad has not had this particular hug injury, so that's the difference in our proportions. By the time the kid is big enough for his shoulder to bonk his father in the chin, he'll be big enough to knock my teeth in.)