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).
I work in industrial design and the use of Alias for surface modeling is quite prevalent (and has been for decades). It used to be called PowerAnimator, and marking menus were first added somewhere around the release of v6 (1995). Alias/Wavefront actually incorporated this functionality into their first release of Maya several years later, trying to innovate on the feature further with the use of hotbox menus [1][2].
Since Alias corp. was later acquired by Autodesk in the early 2000's, you can imagine Fusion 360 as being the symbolical evolution of it. Especially considering the current Alias UI has not changed much since 1999! [3][4]
If interested more on this topic, fun HCI bath-time reading: Gord Kurtenbach's 1993 dissertation on The Design and Evaluation of Marking Menus [5]. Not surprisingly, from Alias/Wavefront he went on to head Autodesk Research for most of the 2000's.
For your iPhone, you can use Color Filters under Accessibility -> Display & Text Size -> Color Filters. Set it to Color Tint and play around with the sliders to your liking (I personally set intensity to ~85%, hue ~8%, and compound it with Night Shift). I also use Reduce White Point (also located in the same place) to further reduce the screen brightness. With these two features, you can get your phone very similar to f.lux.
You can set these two features as active in Accessibility Shortcuts (bottom of the Accessibility menu), allowing them to be quickly toggled by triple clicking the power button. As an alternative gesture, you can also set Accessibility Shortcuts to activate via triple tap on the backside of the phone (Accessibility -> Touch -> Back Tap).
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/