Constant GENERATED_HEADER 

pub const GENERATED_HEADER: &str = "\
<!-- @generated from wit/ by crates/lattice-plugin-api (render.rs).
     Do not edit: run `UPDATE_SITE_REFERENCE=1 cargo test -p lattice-plugin-api`. -->

";

The first line of every generated file. Says what generated it and how to regenerate it, so nobody hand-edits a file the next test run reverts.