[Bug]: AGUI protocol fails to correctly serialize LLM responses when using OllamaChatModel

[CodeWang20]

Describe the bug
When using the official AGUI example with OllamaChatModel, calling the /agui/run endpoint returns an error response: messageId cannot be null.

To Reproduce
For easier debugging and to inspect raw requests/responses, I modified the stream parameter in the streamWithHttpClient call inside OllamaChatModel from true to false. Specifically, in the doStream method:

    @Override
    protected Flux<ChatResponse> doStream(
            List<Msg> messages, List<ToolSchema> tools, GenerateOptions options) {
        return streamWithHttpClient(
                messages,
                tools,
                options.getToolChoice(),
                OllamaOptions.fromGenerateOptions(options),
                false);
    }

When sending a request as per the example, debugging shows that the raw response from Ollama does not contain an id field:

As a result, AguiEvent fails to extract a messageId, causing the client-side to throw an error:

Expected behavior
The system should return the LLM’s response content successfully.

Environment

• AgentScope-Java Version: 1.0.8
• Java Version: 17
• OS: windows

Additional context
When using OpenAIChatModel under identical conditions, everything works as expected.

In contrast, when using JdkHttpTransport with OpenAI, the actual HTTP response does include an id field:

Thus, AguiEvent correctly obtains the messageId, and the client receives the expected response: