Should xbo be a single (selfhosted) or multi (public) user service?

[xuatz]

If we have no intention to make it a multi user service; and by extension a service that should probably only run locally on the user's computer, we can probably ignore bookmark ownership and privacy/encryption concerns. It would also make the implementation easier.

However, if we want to provide a hosted solution, then I think user level encryption is probably mandatory. And it would do us good to implement this early as a first class citizen then an afterthought.