- Write the backend in Rust
- Write the UI in Flutter
- Tie them together using gRPC. You get an API and ability to run client and server on different machines as well
I looked at the flutter to rust bridge and started to play with it, but assuming your UI can withstand the slight overhead of gRPC I found it a simpler way to proceed (although I'm not that far in yet)
Instead I wrote my own RPC system using Serde and Bincode. Communication is over stdio, that way you can support SSH access extremely easily (like VSCode remote).
Unfortunately it was for a company so the code isn't public, but there really wasn't much code to the RPC system at all since you don't need to worry about versioning, authentication, transport, etc. I write a very simple schema language, used Nom to parse it and generate Rust, Typescript and Dart code. The Rust code generation is trivial since you can just `#[derive(Serialize...]`. Typescript / Dart was a bit more complicated (you have to implement Bincode) but it's not very difficult really.
By far the most complex thing is trying to integrate with SSH. If you call `ssh` directly then you end up having to parse non-machine-readable prompts and errors and so on. But if you use a proper SSH library then you end up having to implement ssh-agent, read `~/.ssh/config` etc. yourself which isn't fun either.
NOTE: I found this crate that would likely help with Dart codegen of message types: https://crates.io/crates/serde-generate. While stdin/out wouldn't likely work for me, I could use a TCP socket bound to localhost or named pipe as alternative for the transport piece.
So like a web app.