A scan is saved beside the config and read back after a restart. The next scan starts from it: on a pool with snapshots zfs diff names what changed and only those folders are read; elsewhere a folder whose mtime is unchanged keeps its list and only its kept files are stat'ed again. A cancelled scan keeps what it walked and Resume reads the rest. Forget drops the saved result. The treemap is every file a tile, grouped by folder, with no nested boxes: the folder chains of a Linux system made a staircase of empty headers. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>