[meue]

Not so much constraints per-se, but from a CAD drafting perspective I use Illustrator with Astute's SubScribe [1] plugin (used to be free) and Hot Door's CADTools [2] (one-time cost ~$300). The former is lightweight (e.g. tangency/perpendicular, orient tools) which is pretty nice (especially if you have extend path options from VectorScribe, a separate plugin of theirs). The latter is very robust and probably has some features most people wouldn't need, but lets you get pretty technical with designs.

There's a new UI tool called Dora [3] that has a simple yet novel constraint system that you might like. Tool is still early alpha but growing quickly.

That being said, Graphite's node-based system makes it a viable foundation to build this on! I've helped contribute to the project and Keavon (the creator) definitely has some thoughts on constraint nodes (e.g. for snapping, but also for restraint/relationships).

[1]: https://astutegraphics.com/plugins/subscribe [2]: https://www.hotdoor.com/cadtools/ [3]: https://www.dora.run/