How to use interrupt with astream for frontend interaction?

LangSmith Product Help Deployment
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1

Hi team, thank you for the great work on LangGraph! I’m working on a project and need some help understanding how to properly use interrupt in combination with the astream function.

Setup

  • Frontend: Streamlit app with a simple streaming chat interface.

  • Backend: LangGraph agent with the following node flow:

    1. generate_plan

    2. human_decision — this is where I use interrupt

    3. execute_plan — this executes tools based on the approved plan

The flow looks like this:

generate_plan -> human_decision (interrupt) -> [user approves] -> execute_plan
                                      |
                                 [user rejects]
                                      ↓
                             back to generate_plan with user feedback

My Question

I’m unclear on how to handle the interrupt inside an astream call so that:

  1. The interrupt can pause and wait for user input from the frontend.

  2. The frontend can properly receive and respond to the interrupt (e.g. show a message, buttons, or form for user feedback).

  3. I can then resume the graph flow once the user responds.

What I’d like to understand is:

  • What is the recommended way to yield/return the interrupt back to the frontend when using agraph.astream()?

  • What object/type should I expect or listen for on the frontend side to know when an interrupt has occurred?

  • How do I resume the LangGraph flow after the user provides their input?

Any examples, tips, or best practices would be hugely appreciated!

#help:langgraph

2

Hi! This docs page should help you get started, there is a specific section in Interrupts: How to integrate LangGraph into your React application - Docs by LangChain

3

But i don’t want to use the Langgraph server , i want to implement the backend myself, the langgraph server doesnt provide me with what i want