Package-version trace metadata now uses the LangChain-owned `metadata["lc_versions"]` convention instead of the user-owned `metadata["versions"]` key. Metadata merging is narrowed so only `lc_versions` accumulates nested package-version entries, while generic nested metadata keeps normal last-writer-wins behavior. ## Changes - Renamed `BaseLanguageModel._add_version()` trace metadata from `versions` to `lc_versions`, including docstrings and the non-dict replacement warning. - Scoped `_merge_metadata_dicts()` nested-map accumulation to only `lc_versions`; duplicate package entries remain last-writer-wins and `lc_versions` mappings are copied defensively. - Preserved user-owned `metadata["versions"]` semantics by keeping it out of package-version tracking and generic nested metadata merging. - Updated runnable snapshots and partner package metadata assertions across Anthropic, DeepSeek, Fireworks, Groq, Hugging Face, MistralAI, Ollama, OpenAI, OpenRouter, Perplexity, and xAI to expect `lc_versions`. ## Testing - Added/adjusted core tests for `lc_versions` accumulation, duplicate package overwrite behavior, non-dict `lc_versions` replacement, defensive copying, and `metadata["versions"]` last-writer-wins behavior. - Ran focused core and partner metadata tests plus Ruff checks for changed areas.
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.