feat: add image content support in LangGraph message serialization #3393
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davidzhao
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Sep 13, 2025
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the change itself looks good. could you fix the type errors please?
…rt mixed content types
I've fixed the type errors in the latest commit, could you take another look? |
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Adds image content support to LangGraph message serialization so that messages containing images are properly handled by LangChain/LangGraph pipelines.
Introduced
_serialize_chat_message_content()to handle multimodalChatMessagecontent:Text-only → returns string (backward-compatible).
Multimodal → returns list of blocks:
{"type": "text", "text": "..."}{"type": "image_url", "image_url": {"url": "<image_url>"}}Updated
LangGraphStream._chat_ctx_to_state()to use the serializer forAIMessage,HumanMessage, andSystemMessage.Why
Previously, image content wasn’t serialized into LangChain’s multimodal format, preventing proper handling in graph pipelines.