I've been thinking about something like this as well, for Rust.

I went back and forth with chatgpt trying to get how this would work and look, asked chatgpt to write a doc (warning not proof read, just an AI doc) : https://docs.google.com/document/d/1Kd_cFOXCCm66o7UoIW9Shgxi...

The idea is to have a `llm_fill_in! `macro that runs as a first pass of the build step. Basically, a cargo utility that let's you do stuff like:

```rust

fn add(a: i64, b: i64) -> i64 {

    llm_fill_in!("Adds a and b and returns the result");

```

(excuse the LLM verbosity in the doc, I just was brainstorming with it and asked it to write it as if it was creating an eng spec)

thanks, looks good.