"Yes, I didn't," is a contradiction. The "yes" is positive, but the "not" is negative. If you did not do the act in question, you would reply, "No, I didn't."

Thanks very much.

You didn't do that, did you? 你没有做到这一点，是吗？是 No, I did not do that. 不，我没有这样做 or ' Yes, I did do that ' : 'did do' is for emphasis, to say 'I really did . . ' 是的，我那个 / 是的，我这样做