pub fn watch(
root: &Path,
recursive: bool,
per_dir: bool,
hints: HintSender,
) -> Result<WatchBackend>Expand description
Arm a native watch on root feeding hints. Must be called before
the engine’s initial enumeration so nothing slips between scan and arm.
With per_dir (see per_dir_watching_pays) only root is armed here
and the reconciler arms the rest as it enumerates, so excluded subtrees
never cost a descriptor.