RAILS/DEVISE - Setting a devise cookie to persist across different subdomains

Question

I use devise for authentication and want the following to work:

1. User logs in at [http://mydomain.com].
2. The user makes a payment at [https://secure.mydomai

Answer 1

Addendum: if it still doesn't work although you're pretty sure you deleted your old cookies, rename the cookie's key – just to make sure. (after hours of troubleshooting, this was all I really had to do to make it work.)