I mean sure, you can get the user to download/upload files, but this is very awkward and not suited for storing every change. (But is good for migrating and backing up the data). Having to get the user to manually break the data out of the browser is not a good UX for day-to-day work.
I know that Chrome is pushing for a filesystem API but I don't know if that will be exempt from the usual ephemerality. IIRC it is just a private storage space with a filesystem-like API.
Chrome has an API that allows you to save to files without a new download every time. They made a pretty nice library that wraps that API on Chrome and it gracefully degrades on other browsers.
i noticed this behavior in a drawing app called excalidraw. first save opens a file dialog, subsequent saves just update the file, basically like a standard local text editor.
i keep doing 'save as' to create new files because i don't trust it lol
I know that Chrome is pushing for a filesystem API but I don't know if that will be exempt from the usual ephemerality. IIRC it is just a private storage space with a filesystem-like API.