In cockpit and via API, it is already possible to retrieve the sum of "cleanable" process instances by process definition: https://docs.camunda.org/manual/latest/reference/rest/history/process-definition/get-cleanable-process-instance-report/

This is also displayed on the history cleanup page in Cockpit: https://docs.camunda.org/manual/latest/webapps/cockpit/cleanup/

Currently the sum of all cleanable process instances, decision instances, case instances is not easily accessible (user has to calculate sum manually). It would be helpful if the sum of all cleanable process instances or decision instances could be retrieved with one request or visible in cockpit directly.

AT:

• Sum of all cleanable process instances can be retrieved from API
• Sum of all cleanable decision instances can be retrieved from API
• Sum of all cleanable process instances is visualised in Cockpit
• Sum of all cleanable decision instances is visualised in Cockpit