61fd90a2f3
Fixes missing `run.metadata.usage_metadata` population in `LangChainTracer` for real LLM/chat traces following #34414 - Fix extraction to read usage from serialized tracer message shape: `outputs.generations[*][*].message.kwargs.usage_metadata` - Remove non-serialized direct message shape handling (`message.usage_metadata`) from extractor to match real tracer output path - Clarify tracer docstrings around chat callback naming (`on_chat_model_start` + shared `on_llm_end`) to reduce ambiguity ## Why #34414 introduced usage duplication into `run.metadata.usage_metadata`, but the extractor read `message.usage_metadata`. In real tracer flow, messages are serialized with `dumpd(...)` during run completion, so usage metadata lives under `message.kwargs.usage_metadata`. Because of this mismatch, duplication did not trigger in real traces.
Packages
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.