d3eb2296e7
Fixes #37835 --- When Pydantic collects fields for a `BaseLanguageModel` subclass that defines a `dict()` method, inherited annotations can resolve `dict` against the subclass namespace instead of the builtin. With Pydantic 2.14.0a1 this caused `BaseLanguageModel.metadata: dict[str, Any] | None` to fail during rebuild/import with `'function' object is not subscriptable`. This qualifies the inherited `metadata` field annotation as `builtins.dict[...]`, matching the existing pattern in chat models, and documents why the runtime import cannot move behind `TYPE_CHECKING`. It also adds a regression test that rebuilds a `BaseLanguageModel` subclass with a `dict()` method so core catches this failure before partner packages hit it at import time. Related to #37924, which hardens `_create_subset_model_v2`; this PR fixes the `BaseLanguageModel` class-construction failure directly.
🦜🍎️ LangChain Core
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Quick Install
uv add langchain-core
🤔 What is this?
LangChain Core contains the base abstractions that power the LangChain ecosystem.
These abstractions are designed to be as modular and simple as possible.
The benefit of having these abstractions is that any provider can implement the required interface and then easily be used in the rest of the LangChain ecosystem.
⛰️ Why build on top of LangChain Core?
The LangChain ecosystem is built on top of langchain-core. Some of the benefits:
- Modularity: We've designed Core around abstractions that are independent of each other, and not tied to any specific model provider.
- Stability: We are committed to a stable versioning scheme, and will communicate any breaking changes with advance notice and version bumps.
- Battle-tested: Core components have the largest install base in the LLM ecosystem, and are used in production by many companies.
📖 Documentation
For full documentation, see the API reference. For conceptual guides, tutorials, and examples on using LangChain, see the LangChain Docs. You can also chat with the docs using Chat LangChain.
📕 Releases & Versioning
See our Releases and Versioning policies.
💁 Contributing
As an open-source project in a rapidly developing field, we are extremely open to contributions, whether it be in the form of a new feature, improved infrastructure, or better documentation.
For detailed information on how to contribute, see the Contributing Guide.
Resources
- LangChain Academy — comprehensive, free courses on LangChain libraries and products, made by the LangChain team
- Code of Conduct — community guidelines and standards