On not opening a discussion

I would probably do this: The first time, just pull away. That should give them a message. If they keep doing it just as often, the next time, say something low-key like “Please don’t touch my leg” or “I’d rather not hold hands” or “I prefer not to be touched” or just “Sorry, no” while pulling away. That should give them a message. If they keep doing it just as often, the next time give a firmer message like “It bothers me when you touch me like that.” That should open a discussion.
realsocialskills said:
I mostly agree with you. I think that you’ve described a good progression of ways to assert a boundary.
The point I disagree with you on is that you’ve described this as a way to open a discussion. I don’t think this is about opening discussion; I think it’s about asserting a boundary. The OP does not have to negotiate with her friend. She doesn’t have to convince her that she has good reasons not to want to be touch. OP can have this as a unilateral boundary.
“Don’t touch me” means “don’t touch me”. It doesn’t mean “let’s have an extended emotionally fraught conversation about your desire to touch me.”
If the OP wants to have that conversation with her friend, it’s ok to do that - but it really sounded to me like she just wanted her to stop. And that’s ok too.