Function canonicalize_path 

fn canonicalize_path(path: &str) -> String

Resolve a directory to its realpath and apply NFC normalisation. Wraps the CLI’s _canonicalize_path (falls back to the input, NFC-normalised, when the path can’t be canonicalised: most commonly because it doesn’t exist). NFC is essential on filesystems that don’t auto-normalise (Linux ext4, Windows NTFS) so decomposed inputs still hash to the CLI’s on-disk project-key layout.