[keycloak-dev] Better support authenticationSessions in multiple browser tabs

I am looking at https://issues.jboss.org/browse/KEYCLOAK-5797 issue now. It's about the fact, that when user has opened browser with multiple browser tabs, then after successful login in tab1 (clientA), he may be redirected to the incorrect client (clientB, which was opened in tab2). The thing is, that authenticationSession was tracked by the cookie and didn't support multiple clients. So both browser tabs "tab1" and "tab2" used same authenticationSession, which can reference just one of the clients, hence there could be the conflict and one of the tabs redirected to incorrect client after authentication. I am working on a fix, that allow better support for multiple clients. What I am doing is, that there is "RootAuthenticationSessionModel", which is now referenced by the ID from the cookie. That root session can reference more actual authentication sessions through the map like "Map<String, AuthenticationSessionModel>" . The key is the client UUID. In the Authentication SPI, there are no changes. Those still use the AuthenticationSessionModel as before. This is easily possible as we have "client-id" parameter already available during authentication flows in every tab. So every browser tab can reference correct client and redirect to it. However even with the fix, there is another corner case about support for multiple browser tabs with *same* client. This will be still an issue, especially for the javascript clients. I've created another JIRA https://issues.jboss.org/browse/KEYCLOAK-5938 with the example issue, which can be simulated with our admin console. To properly support multiple tabs of same client, the key will need to be like: "client-id + state" instead of just "client-id" The "state" will need to be either the OIDC/SAML state or some randomly generated string (As in both the OAuth2 and SAML, the state/relayState parameter is not mandatory AFAIK), which will need to be added to the URL during authentication flows as well. Fixing this will take me another few days of work (maybe 2?) as there will need to be change in many files for adding the new parameter + some more authenticationSession model changes etc. So I wonder if we want to: 1) Fix this in 3.4.1 . Will likely mean to delay the release? 2) Fix this in 3.4.2. It will affect many files and there is some chance of regression (hopefully not big as we have lots of the tests for various other corner cases) 3) Fix this later in 4.X . My vote is 1 or 2. WDYT? Any other possibility? Marek