We are using the SSO mechanism, which is working great, with one exception.
If a user is logged in to our main site, then clicks a link to go to the forums, they are not logged in when they hit Discourse. They then hit login and transparently become logged in. This is a bit confusing.
It would be nice if Discourse could detect that the user is logged in to the main site. There are a couple of ways that this could be done, but the most straight forward is a redirect of all non-logged-in users via an SSO URL which will return indicating whether the user is logged in or not. This URL could be the existing SSO url with a parameter to indicate that a reply should come immediately even if the user isn’t logged in, or it could be a completely separate URL. Given that the reply in the case of the user being logged in should look like the reply for a successful SSO login, my gut feel would be to hit the same SSO URL with an extra parameter.
This behaviour could then be optionally enabled via a flag in the settings, maybe “Immediate SSO Login Check” or something like that.