Stop langgraph manually?

[sanjiv-upgiant]

Langgraph currently has END node which will terminate the flow, but sometimes, you would want to terminate any time you would want, so that it would manually end the flow. Is there anyway we can do this?

Maybe from callbacks or signals to interrupt the flow and END it?

[hinthornw]

Like this: https://langchain-ai.github.io/langgraphjs/how-tos/human-in-the-loop/?
Or in any given node you can have a conditional edge after it that ruotes to END if some condition is met

(Moved to a discussion) I think right now there's a couple things.

1. If I'm' just running code locally, and i want to programmatically cancel tasks, I often use asyncio.create_task() to start the code block then cancel the task if needed. Since each step is checkpointed, you'd have your state saved at the last completed step.
2. Once you're thinking about deploying this, we are working on making it easier to create APIs here: https://github.com/langchain-ai/langgraph-example - still python only but working on a JS variant as well

You can start and cancel jobs at will !

[justinlevi]

I have a similar use case where I have a chain defined as:

export async function generationChain(
  abortSignal?: AbortSignal,
): Promise<Runnable<GenerationInput, AIMessageChunk, RunnableConfig>> {
  // Pull in the prompt
  // https://smith.langchain.com/hub/rlm/rag-prompt
  /*
  HUMAN

  You are an assistant for question-answering tasks. Use the following pieces of retrieved context to answer the question. If you don't know the answer, just say that you don't know. Use three sentences maximum and keep the answer concise.

  Question: {question} 

  Context: {context} 

  Answer:
  */
  // const prompt = await pull<ChatPromptTemplate>('rlm/rag-prompt');
  const prompt = ChatPromptTemplate.fromMessages([['human', human]]);

  // LLM
  const llm = new ChatOpenAI({
    modelName: OPENAI_MODEL_4oMini,
    temperature: 0,
  });

  return prompt.pipe(
    llm.bind({
      signal: abortSignal,
    }),
  );
}

I have some ui that sends a request to my server to abort an ongoing stream. I'd like to force the END node after catching the AbortError so I can get one more checkpoint added with the partial generated content