This is great and a very interesting use case.
Custom tools already have support now for scripting so we have a great vehicle for this kind of change.
I am thinking Persona + forced tool use - then from the tool we can run the flow given we already have all the infra to do so. Just need to give custom tools the ability to trigger other llm calls, something that is reasonably simple to add.
Interestingly given custom tools have support for rest calls they can run the entire flow (and just use the discourse rest api to wire this up)
Let me have a think about this over the weekend, and will reply again next week with how I think we can swing this.
Automation chaining is also a very interesting approach here, @joffreyjaffeux have you thought about this problem?