Staging is not deleting
Add anything to the cleanup list with ⌫, from a view, the inspector, easy wins, duplicates or an app’s leftovers. Nothing happens to it. The list shows every path, its size and where it came from.
The confirmation
When you confirm, each path is checked again in the engine — not in the interface — and anything the rules refuse is dropped from the batch with the reason shown. What remains is moved to the Trash through the same call Finder makes.
What cannot be staged
Volume roots, your home folder itself, the shared folder, macOS’s own directories and DiskDuo’s own application and data are blocked outright, however they are reached.
Easy wins
The sidebar gathers the places that fill up by themselves, each measured from your scan: Downloads, caches and logs, iOS simulator runtimes, large media, node_modules, build artifacts, Xcode data, the Trash and package manager caches. A folder that matches a category claims what is inside it, so nothing is counted twice.
Quick Clean on Home stages every category the engine does not flag for a second look, and opens the same review sheet.