Building applications with LLMs through composability
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Kacper Włodarczyk 26a3256fc6
community[major]: DynamoDBChatMessageHistory bulk add messages, raise errors (#30572)
This PR addresses two key issues:

- **Prevent history errors from failing silently**: Previously, errors
in message history were only logged and not raised, which can lead to
inconsistent state and downstream failures (e.g., ValidationError from
Bedrock due to malformed message history). This change ensures that such
errors are raised explicitly, making them easier to detect and debug.
(Side note: I’m using AWS Lambda Powertools Logger but hadn’t configured
it properly with the standard Python logger—my bad. If the error had
been raised, I would’ve seen it in the logs 😄) This is a **BREAKING
CHANGE**

- **Add messages in bulk instead of iteratively**: This introduces a
custom add_messages method to add all messages at once. The previous
approach failed silently when individual messages were too large,
resulting in partial history updates and inconsistent state. With this
change, either all messages are added successfully, or none are—helping
avoid obscure history-related errors from Bedrock.

---------

Co-authored-by: Kacper Wlodarczyk <kacper.wlodarczyk@chaosgears.com>
2025-04-01 11:13:32 -04:00
.devcontainer community[minor]: Add ApertureDB as a vectorstore (#24088) 2024-07-16 09:32:59 -07:00
.github infra(GHA): description is required based on schema definition (#30305) 2025-03-17 18:42:42 +00:00
cookbook docs,langchain-community: Fix typos in docs and code (#30541) 2025-03-28 19:21:16 +00:00
docs community[minor]: Improve Brave Search Tool, allow api key in env var (#30364) 2025-03-31 14:48:52 -04:00
libs community[major]: DynamoDBChatMessageHistory bulk add messages, raise errors (#30572) 2025-04-01 11:13:32 -04:00
scripts infra: update mypy 1.10, ruff 0.5 (#23721) 2024-07-03 10:33:27 -07:00
.gitattributes Update dev container (#6189) 2023-06-16 15:42:14 -07:00
.gitignore infra: gitignore api_ref mds (#25705) 2024-08-23 09:50:30 -07:00
.pre-commit-config.yaml docs: fix builds (#29890) 2025-02-19 13:35:59 -05:00
.readthedocs.yaml docs(readthedocs): streamline config (#30307) 2025-03-18 11:47:45 -04:00
CITATION.cff rename repo namespace to langchain-ai (#11259) 2023-10-01 15:30:58 -04:00
LICENSE Library Licenses (#13300) 2023-11-28 17:34:27 -08:00
Makefile langchain: clean pyproject ruff section (#30070) 2025-03-09 15:06:02 -04:00
MIGRATE.md Proofreading and Editing Report for Migration Guide (#28084) 2024-11-13 11:03:09 -05:00
poetry.toml multiple: use modern installer in poetry (#23998) 2024-07-08 18:50:48 -07:00
pyproject.toml langchain: clean pyproject ruff section (#30070) 2025-03-09 15:06:02 -04:00
README.md docs: edited the badge to an acceptable size (#30586) 2025-04-01 07:17:12 -04:00
SECURITY.md docs: single security doc (#28515) 2024-12-04 18:15:34 +00:00
uv.lock openai[patch]: support Responses API (#30231) 2025-03-12 12:25:46 -04:00
yarn.lock box: add langchain box package and DocumentLoader (#25506) 2024-08-21 02:23:43 +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.

LangChains ecosystem

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.

Additional resources

  • Tutorials: Simple walkthroughs with guided examples on getting started with LangChain.
  • How-to Guides: Quick, actionable code snippets for topics such as tool calling, RAG use cases, and more.
  • Conceptual Guides: Explanations of key concepts behind the LangChain framework.
  • API Reference: Detailed reference on navigating base packages and integrations for LangChain.