So what I came up with is a Marshaller for each top level node type, that wraps in a "node" struct (type string and object any), and local type to avoid an infinite loop.

This works fine, but not sure if there's a better way of doing it.

Providing the MarshalJSON for each node isn't terrible.

For now this is fine. The JSON is readable and it works fine when I want to check something in the AST. So WIN! 🎉