[Release] langchain-ai/langchain langchain-core==1.4.5: langchain-core==1.4.5

langchain-core version 1.4.5 introduces validation for tool call chunks during streaming, fixes an async tracer fallback issue in sync contexts, and tightens structured output model fallbacks. This release improves streaming reliability and error handling for chat models and structured outputs.

Key Points

• •Tool call chunks are now validated during streaming to ensure data integrity
• •Async tracer `on_chat_model_start` callback now has proper fallback behavior in synchronous contexts
• •Structured output model fallbacks have been tightened to prevent unexpected behavior
• •Standard tests enhanced to catch tool call streaming issues early
• •Improved compatibility between async and sync execution contexts
• •Better error handling for chat model initialization and structured outputs

Workflow Diagram

Concepts