Mason Daugherty
2ade674ffc
`ModelFallbackMiddleware` now removes unsupported cache keys and Fireworks session-affinity headers before fallback attempts, while preserving cache settings supported by the selected fallback model. --- When an agent falls back to another provider, explicitly supplied cache settings in `ModelRequest.model_settings` can reach a model that does not accept them and cause the fallback to fail. `ModelFallbackMiddleware` now removes `x-session-affinity` for non-Fireworks fallbacks and removes `prompt_cache_key` for providers outside Fireworks, OpenAI, and Azure OpenAI. It preserves unrelated settings and headers, retains the existing Anthropic cache-marker handling, and leaves the original request unchanged. Unit tests cover synchronous and asynchronous fallback, supported cache-key preservation, and header cleanup. Stacked on #38823. This PR contains only the fallback cleanup and its tests. The Fireworks middleware in the base PR works independently because its generated affinity is consumed directly by `ChatFireworks`. Review focus: provider support is determined through `_llm_type`; `prompt_cache_key` is shared by multiple providers and must not be treated as Fireworks-only.
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
model-profiles/ # Model capability profiles and CLI (`langchain-model-profiles`)
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.