[tunesmith]

Oh, so you can only crosslink from different root nodes. That makes sense.

There are so many ways to structure todos. In this case, it appears to be using subtasks specifically to break things down in various ways, and it's a cool implementation.

I personally think of todos as having dependencies, like a simplified PERT chart, which would more require a DAG. If I brought in the ability to generalize groups of that graph (or in the other direction, take a general node and "break it down" into a group of nodes), I guess I'm thinking of a multi-graph there. That sounds really hard. :)