In the simplest scenario where one uses a line and rigdoctor to create a simple rig, how can one define the order of the hierarchy?
Reversing the point order with a sort node does not reverse the joint hierarchy. Is this a bug?

The rig hierarchy is based on the vertex connections between the line primitives, not the point order - in your example if you place a "Reverse" node after the line to swap its vertex order, that would flip the hierarchy.

aias
In the simplest scenario where one uses a line and rigdoctor to create a simple rig, how can one define the order of the hierarchy?
Reversing the point order with a sort node does not reverse the joint hierarchy. Is this a bug?

I noticed that and I've run in some problems with other nodes because of that. I've been using the transverse op (in apex) to get a better point ordering. The skeleton node doesn't seem to keep the correct vertex order either, so using that to sort points won't help as well.

I'm not sure what you mean by incorrect vertex order? For a skeleton, the primary thing of importance is the parent-child relationship. I wouldn't try to depend on the order between siblings.