Sydney Runkle d5ba5d3511 feat(langchain): improved HITL patterns (#32996)
# Main changes / new features

## Better support for parallel tool calls

1. Support for multiple tool calls requiring human input
2. Support for combination of tool calls requiring human input + those
that are auto-approved
3. Support structured output w/ tool calls requiring human input
4. Support structured output w/ standard tool calls

## Shortcut for allowed actions

Adds a shortcut where tool config can be specified as a `bool`, meaning
"all actions allowed"

```py
HumanInTheLoopMiddleware(tool_configs={"expensive_tool": True})
```

## A few design decisions here
* We only raise one interrupt w/ all `HumanInterrupt`s, currently we
won't be able to execute all tools until all of these are resolved. This
isn't super blocking bc we can't re-invoke the model until all tools
have finished execution. That being said, if you have a long running
auto-approved tool, this could slow things down.

## TODOs

* Ideally, we would rename `accept` -> `approve`
* Ideally, we would rename `respond` -> `reject`
* Docs update (@sydney-runkle to own)
* In another PR I'd like to refactor testing to have one file for each
prebuilt middleware :)

Fast follow to https://github.com/langchain-ai/langchain/pull/32962
which was deemed as too breaking
2025-09-17 16:53:01 -04:00
2025-07-28 15:03:25 -04:00
2025-07-30 23:04:45 +00:00
2025-07-27 20:00:16 -04:00
2025-09-08 20:06:59 +00:00

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Note

Looking for the JS/TS library? Check out LangChain.js.

LangChain is a framework for building LLM-powered applications. It helps you chain together interoperable components and third-party integrations to simplify AI application development — all while future-proofing decisions as the underlying technology evolves.

pip install -U langchain

To learn more about LangChain, check out the docs. If youre looking for more advanced customization or agent orchestration, check out LangGraph, our framework for building controllable agent workflows.

Why use LangChain?

LangChain helps developers build applications powered by LLMs through a standard interface for models, embeddings, vector stores, and more.

Use LangChain for:

  • Real-time data augmentation. Easily connect LLMs to diverse data sources and external/internal systems, drawing from LangChains vast library of integrations with model providers, tools, vector stores, retrievers, and more.
  • Model interoperability. Swap models in and out as your engineering team experiments to find the best choice for your applications needs. As the industry frontier evolves, adapt quickly — LangChains abstractions keep you moving without losing momentum.

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While the LangChain framework can be used standalone, it also integrates seamlessly with any LangChain product, giving developers a full suite of tools when building LLM applications.

To improve your LLM application development, pair LangChain with:

  • LangSmith - Helpful for agent evals and observability. Debug poor-performing LLM app runs, evaluate agent trajectories, gain visibility in production, and improve performance over time.
  • LangGraph - Build agents that can reliably handle complex tasks with LangGraph, our low-level agent orchestration framework. LangGraph offers customizable architecture, long-term memory, and human-in-the-loop workflows — and is trusted in production by companies like LinkedIn, Uber, Klarna, and GitLab.
  • LangGraph Platform - Deploy and scale agents effortlessly with a purpose-built deployment platform for long-running, stateful workflows. Discover, reuse, configure, and share agents across teams — and iterate quickly with visual prototyping in LangGraph Studio.

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