Why We Keep Process Data Outside the Engine — and Why It Changes Everything for Agentic BPM

There is a design decision at the heart of in-concert that surprises people when they first encounter it: the engine knows nothing about your data . No domain objects stored inside the engine. No variable interpolation in BPMN expressions. No built-in scripting that reaches into your database. When a process instance is running, the engine holds exactly one thing that belongs to you: an instanceId . Everything else — documents, application state, business context, AI responses — lives in your systems, bound to that id. This is not an oversight. It is the central architectural choice, and it shapes everything else about how in-concert works. And this is the beginning of #agenticbpm. The Problem with Data-Coupled Engines Traditional BPM engines — Camunda, Flowable, Activiti — manage process variables alongside process state. You deploy a BPMN, you pass in variables, and the engine stores them, interpolates them into conditions, and threads them through the execution. It is convenient at