Hey Andreas,
How are you? It seems like you’re always working on something interesting.
I ran across a similar problem and wasn’t able to figure out how to do this. It would be sort of cheating, but you could save the session data to a database and then use if from there. You could keep track of this database data by using a session flag. If it’s a “new” session, then clear the data from the database.
Have fun (I’m sure you will),
Yisrael