> The idea of it potentially just up and vanishing with a browser update.

Anyone writing applications in the browser should be very cautious to note that many browsers will jettison some types of their website storage if disk space is low.

This is frustrating at the best of times, but if there's no server-side backup then frustration would be an understatement.

I am not sure if this caveat applies to localStorage but from experience it does to IndexedDB — seemingly even in Electron applications (??).