Since I built this, my thoughts have been running in the direction of turning it into a full graph editor.
However, all the graphs I want to create also have other constraints. Sometimes I want a sort of activity diagram (
https://plantuml.com/activity-diagram-beta), other times I want some edges always be horizontal and to line up with similar edges.
I've also been thinking about the clunky drawing primitives I chose in
http://akkartik.name/lines.html. Writing text inside shapes doesn't really work, which is like literally the first thing one might want to do with line drawings.
Putting these thoughts together, I've been imagining a 2-level tool with a tray on the left like in
Recursive Drawing or
Crosscut, where I can draw some primitives into the tool tray and then attach hotkeys to them to compose them into pictures in the main area.