This might have an obvious answer for the more experienced here, but (potentially stupid question) why didn't you use dart for this?

Nothing against rust, just interested is all considering the dart/flutter relationship.

Speaking only for myself, I'm considering Flutter + Rust because I want to write everything in Rust, but there aren't great GUI options for Rust atm. I've heard good things about the rust<->dart bridge so it seems like a reasonable compromise, esp. given the Dart code to write Flutter UIs seems fairly declarative. Hoping to keep most of the logic in Rust and just the view in Flutter/Dart.