[greymule]

Batter attempts to bunt. Bat over the plate. Ball bounces straight down and comes up and hits the batter's forearm, also over the plate. Both feet still in the box.

The ball may be out of the box, but I'd sure prefer to call that a foul (and I do).

However, ball rolls out in front of the plate, and the batter kicks the ball as she starts toward 1B. One foot still in. I call that an out, because the batter made the contact and the ball was out of the box. But I guess I've been inconsistent, because if the batter had one foot out and still had the other foot in, and the ball bounced up and hit her, I've been calling that a foul. Sort of "ball hits batter, foul; batter hits ball, out," though of course that's not substantiated by rule.

I guess "within the batter's box" has to be defined more clearly.

Good question.