This is very slick! Regard to editability of text diagram, brainstorming here: it would be cool to have two-way convertibility between text diagram and svg diagram. so users can use drag and drop like interaction to edit the svg diagram, and convert back to text diagram, so it has the best of both worlds. I guess roughly this idea already exists — there is program that converts image to ascii, but it lacks precision, as in the ascii to svg and then back to ascii would yield to different set from the starting point.