launcher/build.rs

//! Rebuild the crate when the build identity changes.
//!
//! `option_env!("SM121_VERSION")` is baked at compile time, but cargo does not
//! treat an env var as an input on its own — without this line a cached build
//! keeps the old value (the add-on's 1.3.6/1.3.7 images both shipped "dev"
//! from a warm `target/` cache mount). `cargo:rerun-if-env-changed` makes the
//! crate recompile whenever the version passed by the CI changes.
fn main() {
    println!("cargo:rerun-if-env-changed=SM121_VERSION");
}