The First Altercation

We had the first cat-scratching-baby incident on Thursday this week. The cats have been very tolerant, allowing their fur to be pulled and their naps disrupted, and I can report that Lumi brought this scratching upon herself.
The implement, Mr. Lau's paw:

The wound, on Lumi's left hand:

Here's how it went down: Lumi saw one of the cats' favorite toys, a cute little ball with a bell inside, and reached for it. She was sitting in her little chair, so I got it for her. She was holding it in her hand and looking at it when Mr. Lau came over to see. He looked at me like "that is MINE" and I looked back at him like "i know but we talked about sharing" and he very maturely walked away and went over to the cat tree. That's when Lumi pulled a jerk move: she reached back to the cat tree and held the ball out right next to Lau and waved it back and forth enticingly in his face. And Mr. Lau very gently pawed at her hand with the ball to participate in her game.
And she cried.
But not very much! There weren't even any tears, only a kind of whimpering for a bit.
Here is a better look at the injury: