Function kernel_path 

pub fn kernel_path() -> PathBuf

Where the Mode B kernel is looked for.

BECK_KERNEL names the module; without it, the path cargo build -p beck-wasm --release --target wasm32-unknown-unknown writes to, relative to the working directory. The kernel is a build artefact of this workspace rather than something compiled into the binary, because building it needs a target the compiler’s own build does not: making beck depend on a wasm toolchain to serve a Mode A page would be the wrong trade.