Glossary
Preview before cleaning
A required look at the files a clean will touch, before anything is removed.
A preview is the list of items an action will affect, shown while you can still refuse. For a disk cleaner, it is the difference between a path you recognize and a path you would have regretted. It is not a summary count. A count without names is how the wrong node_modules disappears.
Disk Housekeeper always previews before cleaning. That includes Smart Clean and Autopilot. Auto-Sort is previewed before the sort is applied. The default removal destination is the Trash, which is a second chance after the preview, not a replacement for it.