How can I add a template for Assistant to the user's request in ChatAsync() with History?

### Description

await foreach (string response in session.ChatAsync(new ChatHistory.Message(AuthorRole.User, input),
    inferenceParams,
    cancellationTokenSource.Token))

After the user's request, I want to add:

role: assistant, message: think\n\nthink\n\n

This is necessary to explicitly disable reflection for Qwen3. Because the /think or /no_think directives don't work stably.
