langchain-middleware

To add human-in-the-loop approval to a LangChain agent, you integrate custom middleware that creates pause points before executing dangerous tool calls. This requires setting up a Checkpointer and specifying a thread_id to manage the HITL workflow state.

Custom middleware in LangChain is used to intercept specific tool calls within agents, enabling you to add error handling, logging, and retry logic. It provides a framework to safeguard critical actions by pausing for human approval before execution.

Yes, you need a Checkpointer and a thread_id to pause LangChain tool calls for human review. These components are required to save the agent state and manage human-in-the-loop decision-making workflows effectively.

You generate structured output with LangChain middleware by implementing Pydantic or Zod schemas within your agent framework. This integration allows the middleware to format and validate tool call data for easier downstream processing.

Yes, you can use LangChain middleware to intercept and review sensitive emails before sending. By configuring an agent with human-in-the-loop pause points, the workflow pauses the email tool call to allow a human to review and approve the content.

The primary limitation of human-in-the-loop middleware in LangChain is its dependency on a Checkpointer and thread_id to function. Additionally, HITL workflows inherently introduce latency by pausing automated processes to wait for human decision-making.