Use case: User fills out a form to add a product and register at once. When the user has submitted the combined form, the app authenticates the user and is logged in (assume validations passed) without the need to confirm or login.
I've removed the confirmable feature out, but when the user fill out the form, it succeeds, but the user doesn't get logged in unless they go to a login form. This isn't such a great experience, so is there a way to Register a user and immediately log them in?