processing:
  - branch:
        processors:
          - cache:
              key: ${! meta("umh_topic") }
              operator: get
              resource: last_state
        result_map: root.last_state = this

    - cache:
        key: ${! meta("umh_topic") }
        operator: set
        resource: last_state
        value: ${! json("state") }

With this you could cache the entries, and based on the umh_topic return either null or the aggregation 🙂 https://cdn.discordapp.com/attachments/984082664678125578/1425754541130776648/image.png?ex=68e8bce3&is=68e76b63&hm=14be8e2f56c891cae18a7d0d6873e9d70a48163069d486f568a21997a8637e36&