langchain

11a54b1f - docs: clarify `SystemMessage` usage in LangGraph agent notebook (#32320) (#32346)

docs: clarify `SystemMessage` usage in LangGraph agent notebook (#32320) (#32346) Closes #32320 This PR updates the `langgraph_agentic_rag.ipynb` notebook to clarify that LangGraph does not automatically prepend a `SystemMessage`. A markdown note and an inline Python comment have been added to guide users to explicitly include a `SystemMessage` when needed. This improves documentation for developers working with LangGraph-based agents and avoids confusion about system-level behavior not being applied. --------- Co-authored-by: Mason Daugherty <mason@langchain.dev>