How to update subgraph state outside of execution?

LangSmith Product Help Deployment
1

I have a LangGraph workflow where a sub-agent completes a process and stores results both in my own database and in the LangGraph database.

However, I also want to perform some operations on the same thread_id simultaneously, which requires updating the same field in the state at the same time. From my understanding, LangGraph currently doesn’t support this kind of concurrent state update. Is that correct?

So I am considering updating my own DB first via a separate API, and then syncing that state back to LangGraph. I saw the update_state method, but it seems like it doesn’t support subgraphs.

My questions are:

  1. Is there any method to update subgraph state outside of execution?

  2. If not, what’s the recommended way to keep my DB and LangGraph’s state in sync in this scenario?