All tests run on an 8-year-old MacBook Air. Open a PDF on macOS and the OS quietly logs it in at least five places: Recent Documents (NSDocumentController) Finder's recent items (LSSharedFileList) App cache directory QuickLook thumbnail cache Rendering cache under ~/Library/Caches/ Sanctuary Viewer blocks all of them. Blocking Recent Documents macOS auto-registers opened files via NSDocumentCo