Sorry if maybe I’m saying the most obvious but I see the problem origin on this issue on WebKit WebView
I tried workarounds mentioned here on discourse forum with no success
One of my colleagues (he’s a web programmer, me not) purposed to change something on the SSO provider (not myforum.com/session/sso_provider) so that when it calls the forum sends a GET in URL querystring with an extra parameter login=mylogin
Likely the token creation call goes
from myssoprovider.com/sso?sso=xxxxx&sig=xxxxx
to myssoprovider.com/sso?sso=xxxxx&sig=xxxxx&login=mylogin
But AFAIK it’s not possible to implement such a thing on discourse side from settings panel, rather it’s a mod that goes deeper and can cause problems or going lost in updates.
Thanks for your suggestions