As far as I understood it from the doc and experienced it in my S2 app, the sessions are not keep alive ones.
Even if it may be a security weakness at some points and in some business contexts, many users will ask for keep alive sessions, and do not want to be forced to reconnect after a given amount of time.

Do you think it could be possible to implement this in the next future of S2?
With a new parameter such as idle_lifetime?

Thanks