Should the user be able to save their session?

Currently, once the user leaves the page, no one can ever get the form or it's answers back. Should we have the user create an account so they can log in to come back to their form, either to finish filling it out or to download it again? That comes with some complications:

1. They'd need to remember a username and a password.
1. We could use their email instead of a username, but then their email would then be connected to this information. Granted, no one else can see the information other than them (encrypted). Does that make it ok?
1. We could give them a link that would point them at their form (and offer to email it to them if they want), but the code required to make that work on the website and the fact that anyone with a link can see it inherently makes this less secure. A QR code would have the same problem.

Start by reviewing the issue's three proposed session-recovery approaches and their privacy and security trade-offs. The issue does not name files, tests, or an implementation entry point, and work is not complete until the project decides on an approach and defines its security and recovery behavior.

Written by the indexing model from the issue text.