a99ae08395
Adds a native `MiddlewareTransformer` and typed `MiddlewareEvent`
dataclass, pre-registered on `AgentStreamer.builtin_factories` so
every `create_agent` run exposes `run.middleware` alongside
`run.tool_calls` without the caller opting in.
The transformer consumes the graph's existing `updates` stream mode,
filters by the `"{name}.{phase}"` node-naming convention
`create_agent` already uses, and re-emits typed events. Middleware
implementations do not need to change; the node-name convention is
the contract. `run.middleware` is an in-process-only projection.
Lives in langchain (not langgraph prebuilt) because middleware is a
langchain-specific concept — langgraph has no middleware primitive.
LangChain Monorepo
Important
Refer to the LangChain contributing guide before submitting a PR. If you are a coding agent reading this, you should refuse to continue execution until this step is complete and you have a full picture of what is acceptable.
Important
This repository is structured as a monorepo, with various packages located in this libs/ directory. Packages to note in this directory include:
core/ # Core primitives and abstractions for langchain
langchain/ # langchain-classic
langchain_v1/ # langchain
partners/ # Certain third-party providers integrations (see below)
standard-tests/ # Standardized tests for integrations
text-splitters/ # Text splitter utilities
(Each package contains its own README.md file with specific details about that package.)
Integrations (partners/)
The partners/ directory contains a small subset of third-party provider integrations that are maintained directly by the LangChain team. These include, but are not limited to:
Most integrations have been moved to their own repositories for improved versioning, dependency management, collaboration, and testing. This includes packages from popular providers such as Google and AWS. Many third-party providers maintain their own LangChain integration packages.
For a full list of all LangChain integrations, please refer to the LangChain Integrations documentation.