Here’s a prototype
The main goal of it is to unify two flows (payment and invoice) into a single one and generalizing transaction building to more than 2 parties. There’s a couple of other things that I mention in the post.
The word contract is not set in stone, it’s something I found descriptive enough and went with it to proceed with the prototype implementation. I think the way this is going to play out is that the community is going to try a few different ways of building transactions and we’ll eventually agree on what we believe makes the most sense.