An open paragraph with a draft that was not applied yet was not counted as unsaved work, so closing the tab or quitting skipped the save prompt. The test opens a paragraph, types into it, and checks that first_dirty() reports the tab (and not before typing, nor after the original text is typed back). Without the line_editor check in has_unsaved_work, first_dirty() stays None and the assertion fails (left: None, right: Some(0)).