pub fn detect_language_cache_root(
candidate: &Path,
) -> Option<(&'static str, PathBuf)>Expand description
If candidate sits inside a known language cache, return (label, root)
where root is the path truncated at the end of the marker directory (no
trailing slash). resolve_path uses this to auto-register a session read-only
root so the retry resolves without a config edit or a subprocess (#899).