Until now the only way a book got into Aoede was the in-app import button. On macOS you can now right-click an EPUB, PDF, or text file in Finder, choose Open With Aoede, or just drag it onto the icon, and it imports and opens straight into the reader.
The one decision worth noting is that Aoede registers as an alternate handler, not the default one. Double-clicking a PDF still opens Preview the way it always did. Aoede only shows up in the Open With menu when you go looking for it, so it earns a place in the workflow without taking over file types that already have a home. The open routes through onOpenURL into a small openExternalFiles path that dismisses onboarding first, so a file opened on a fresh install lands in the reader instead of getting stranded behind the welcome screen.