Unverified50% confidenceFactExact time
Message State内部维护一个消息列表，新消息通过Reducer策略默认以追加模式合并到已有列表中
1
Sources
50%
Confidence
Long-term
Relevance
8/22/2026
First Seen
Sources
Related Claims
UnverifiedIn LangGraph, each message field uses the add_messages reducer by default; nodes only need to return newly added messages, and the framework automatically appends them to the history list rather than overwriting it.64% similarUnverifiedThe system prompt is placed at the top of the messages list on every API call, identified by role: system.63% similarUnverifiedThe old prompt= parameter remains available, and LLM will automatically upgrade it to a single-message array in the background to maintain backward compatibility.62% similarUnverified多轮对话中System消息设定行为基调和约束，user消息代表用户输入，assistant消息是模型的历史回复62% similarUnverifiedA System Prompt is persistent and remains in effect throughout the entire session.62% similar
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