Oh, this is very, very cool, and very, very timely!

Paper here: https://declarative-dragging.github.io/D2.pdf

IMO one of the remaining gaps of agentic coding is that it's hard for even multimodal LLMs to check interactive motion effects for correctness and "feel." Like, sure, they can take screenshots of a few snapshotted states, but in terms of how things react as underlying nodes move and (potentially) reflow. How do you QA the feel of moving your wrist rapidly in the context of nested zones?

The answer is that you avoid the need to: you have a (nearly-provably) correct foundation that ensures that behavior is predictable regardless of state, and just render accordingly.

The paper's approach is incredible here: simultaneous optimistic rendering of multiple possible states, and a composable algebra (a small combinator language) over how drop zones and distance are derived - allowing for an extremely high-level interface in practice. Everything feels snappy and right, and the code you write is about as minimal as you can get - though the paper notes that state management is somewhat complex. But this seems solvable!

Once this is ported to HTML, it'll become an incredible part of the modern dev toolkit. I'm very excited for what this means.