I had need to implement a new SingleSessionCommandService (logical mirror of the original unless registerRollbackSync (), which is no longer invoked and JoinTransaction).
The primary thread creates statefulKnowledgeSession via JPA (JTA). The secondary thread load the session, insert facts, fire rules, startProcess, and dispose.
In @PreUpdate on SessionInfo, when you create the same snapshot is retrieved correctly, during the insertion of a fact, I get a NPE on org.drools.reteoo.ReteooWorkingMemory at 245: factHandle is null. In debugging I verified that the method throws the exception FromNode.evaluateAndPropagate captured by the command.