.Net: Bug: Unexpected Accumulation of Previous Assistant Messages in Final Response Using InvokeStreamingAsync

[nels-ai-source]

Describe the bug
When using the InvokeStreamingAsync method of ChatCompletionAgent, and receiving multi-turn conversation responses in the OnIntermediateMessage, it was found that the final assistant message included previous assistant messages. It appears that the last message accumulates all previous assistant messages. I am not sure if this is a bug, but it has caused confusion during usage.

To Reproduce
Steps to reproduce the behavior:

Define a ChatAgent with provided tools.

ChatCompletionAgent agent = new()
{
    Instructions = processRequest.AgentRequest.Instructions,
    Kernel = processRequest.Kernel,
    HistoryReducer = new ChatHistoryTruncationReducer(6, 4),
    Arguments = new KernelArguments(new OpenAIPromptExecutionSettings
    {
        Temperature = 0,
        FunctionChoiceBehavior = FunctionChoiceBehavior.Auto(functions: processRequest.AgentRequest.Functions, autoInvoke: processRequest.AgentRequest.Functions?.Count > 0, options: new() { RetainArgumentTypes = true })
    })
};

Receive messages in OnIntermediateMessage and notice overlapping data.
Expected behavior
Each message should be independent and non-repetitive.

Platform

Language: C#
Source: 1.56.0
IDE: Visual Studio
OS: Windows