[wg0]

The authentication account should have a permanent stable identifier that should be the provider's responsibility to issue and manage.

Everything else including email and username should be changeable (provided there's no conflict with other accounts)

[Wowfunhappy]

> (provided there's no conflict with other accounts)

Couldn't you use this to figure out which emails have registered with Claude?

[bathtub365]

You can do this on almost every online service by trying to create an account with an email that already has an account.