Mason DaughertyandGitHub
385033fd9c
Preserve LangChain package-version trace metadata when graph-bound config and invoke-time config both contribute `lc_versions`. The earlier broad nested metadata merge has been narrowed to the LangChain-owned `lc_versions` namespace, so arbitrary user metadata keeps the existing last-writer-wins behavior. ## Changes - Add a shared metadata merge path used by `merge_configs()` and `ensure_config()` so top-level metadata keys are preserved across bound and runtime configs. - Special-case only `metadata["lc_versions"]` for one-level package-version accumulation; duplicate package entries remain last-writer-wins and non-mapping values still replace. - Keep generic nested metadata maps, including user-owned `metadata["versions"]`, as replacement-only to avoid changing arbitrary metadata semantics. - Raise the `langchain-core` lower bound to `>=1.4.7` so LangGraph’s `lc_versions` handling aligns with the lc-core package-version instrumentation. - Cover both config merge helpers with tests for `lc_versions` accumulation, non-recursive replacement within the package map, generic nested metadata replacement, and defensive copying of mapping values. ## Test note The stream event assertions for `test_imp_exception` now avoid depending on leaked internal task-path metadata. With older `langchain-core`, callback metadata could be mutated by later task runs, so every task event in this test appeared to have the final task path index. That made even the `task_with_exception` start event report `metadata["langgraph_node"] == "my_task"`, which is inconsistent with the event name. `langchain-core>=1.4.6` preserves per-event metadata more accurately: the first `my_task`, `task_with_exception`, and second `my_task` report distinct task path indexes. The test now asserts the stable behavior instead: event sequence, tags, required metadata, root stream payloads, exception handling, and final outputs, without requiring the old leaked task index.
Low-level orchestration framework for building stateful agents.
Trusted by companies shaping the future of agents – including Klarna, Replit, Elastic, and more – LangGraph is a low-level orchestration framework for building, managing, and deploying long-running, stateful agents.
pip install -U langgraph
Tip
If you're looking to quickly build agents, check out Deep Agents — a higher-level package built on LangGraph for agents that can plan, use subagents, and leverage file systems for complex tasks.
For an equivalent JS/TS library, check out LangGraph.js and the JS docs.
Why use LangGraph?
LangGraph provides low-level supporting infrastructure for any long-running, stateful workflow or agent:
- Durable execution — Build agents that persist through failures and can run for extended periods, automatically resuming from exactly where they left off.
- Human-in-the-loop — Seamlessly incorporate human oversight by inspecting and modifying agent state at any point during execution.
- Comprehensive memory — Create truly stateful agents with both short-term working memory for ongoing reasoning and long-term persistent memory across sessions.
- Debugging with LangSmith — Gain deep visibility into complex agent behavior with visualization tools that trace execution paths, capture state transitions, and provide detailed runtime metrics.
- Production-ready deployment — Deploy sophisticated agent systems confidently with scalable infrastructure designed to handle the unique challenges of stateful, long-running workflows.
Tip
For developing, debugging, and deploying AI agents and LLM applications, see LangSmith.
LangGraph ecosystem
While LangGraph can be used standalone, it also integrates seamlessly with any LangChain product, giving developers a full suite of tools for building agents.
To improve your LLM application development, pair LangGraph with:
- Deep Agents – Build agents that can plan, use subagents, and leverage file systems for complex tasks.
- LangChain – Provides integrations and composable components to streamline LLM application development.
- 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.
- LangSmith Deployment – 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 LangSmith Studio.
Documentation
- docs.langchain.com – Comprehensive documentation, including conceptual overviews and guides
- reference.langchain.com/python/langgraph – API reference docs for LangGraph packages
- LangGraph Quickstart – Get started building with LangGraph
- Chat LangChain – Chat with the LangChain documentation and get answers to your questions
Discussions: Visit the LangChain Forum to connect with the community and share all of your technical questions, ideas, and feedback.
Additional resources
- Guides – Quick, actionable code snippets for topics such as streaming, adding memory & persistence, and design patterns (e.g. branching, subgraphs, etc.).
- LangChain Academy – Learn the basics of LangGraph in our free, structured course.
- Case studies – Hear how industry leaders use LangGraph to ship AI applications at scale.
- Contributing Guide – Learn how to contribute to LangChain projects and find good first issues.
- Code of Conduct – Our community guidelines and standards for participation.
Acknowledgements
LangGraph is inspired by Pregel and Apache Beam. The public interface draws inspiration from NetworkX. LangGraph is built by LangChain Inc, the creators of LangChain, but can be used without LangChain.