pub fn cache_dir_under(root: &Path, key: &str) -> Option<PathBuf>Expand description
The same derivation against an arbitrary root — for the local-container
placement, whose cache lives under the camp’s own .yah/cache and has
no HOST_ROOT to hang off. Split out for the same reason
super::forge_produced::host_path_under is: the key validation is the
whole safety content of both, and two copies is one copy that can be
fixed alone.