How to deal with silence input in conversation built by RASA?

Rasa Open Source
2
  1. how to detect user’s silence in conversation?

It’s best to do this in your front end (widget or mobile app).

  1. when user’s slience is detected, how to trigger my utter_action?

Silence isn’t detected. Rasa isn’t actively tracking the time since a last utternace was made.

You could write a separate app that monitors the tracker store or reads the event queue and your app could keep silence timers but it would be better for your front end UI to do this.