(** Recursive directory tree operations. *)

val hardlink :
  source:Fpath.t -> target:Fpath.t -> (unit, [> Rresult.R.msg ]) result
(** [hardlink ~source ~target] recursively hardlinks the tree rooted at
    [source] into [target]. Falls back to {!copy} on EMLINK (too many
    links). Symlink targets in the source tree are preserved as symlinks. *)

val copy :
  source:Fpath.t -> target:Fpath.t -> (unit, [> Rresult.R.msg ]) result
(** [copy ~source ~target] recursively copies the tree rooted at
    [source] into [target], preserving permissions and modification
    times. *)

val clense :
  source:Fpath.t -> target:Fpath.t -> (unit, [> Rresult.R.msg ]) result
(** [clense ~source ~target] removes files from [target] that are
    identical to their counterparts in [source] (compared by mtime).
    Also removes directories in [target] that become empty after
    removal. Used after overlay builds to extract only new/changed
    files. *)