Proactive messaging with Kafka

I'm trying to send proactive messages in NODEJS, and I know how it could be done once you start it from an event, like for example, a user join a channel, or even on a onMessage() event, where you can get the context and then get a list of users and finally send then some message. It is pretty clear on the docs.

But I have a different scenario. I intend to get a message, and then send it to a broker like Apache Kafka.

Once it is done, I will subscribe my bot to another topic in Apache Kafka, and then I will send it back to the user.

I will try to summarize my issue:

I get a message by using the onMessage() event, and instead of reply that message strait foward I send it to Apache Kafka to be processed; by this time I will lost the context.

Later when Apache Kafka processed the answser to be sent to the user I don't have the context anymore. But I could store de userID and TenantID and try to recreat the context and then simplely send it.

My problem is: I have no idea how to get the context outside of an event, even if I have the user and tenant id.

I've made a diagram in order to make it clear, I hope it does.

Could you help me?

Thanks in advance.