Checked other resources

• This is a bug, not a usage question. For questions, please use the LangChain Forum (https://forum.langchain.com/).
• I added a clear and detailed title that summarizes the issue.
• I read what a minimal reproducible example is (https://stackoverflow.com/help/minimal-reproducible-example).
• I included a self-contained, minimal example that demonstrates the issue INCLUDING all the relevant imports. The code run AS IS to reproduce the issue.

Example Code

from langgraph.graph import MessagesState, StateGraph

def node_1(state):
    return {"a": 1}

def node_2(state):
    return {"b": 2}

# 添加节点
builder = StateGraph(MessagesState)
builder.add_node("开始", node_1)
builder.add_node("结束", node_2)

# 设置流程
builder.set_entry_point("开始")
builder.add_edge("开始", "结束")
builder.set_finish_point("结束")

# 编译图
graph = builder.compile()

print(graph.get_graph().draw_mermaid())

Error Message and Stack Trace (if applicable)

Description

When node names are Chinese text and Chinese text length is the same, mermaid image is wrong:

the reason I saw is: It replace Chinese text to "__" (one Chinese char, one _ symbol)

System Info

langgraph==0.6.6