Developed a user-configurable mechanism for accumulating tool call IDs in streaming OpenAI responses within the langchain4j/langchain4j repository. This work introduced the accumulateToolCallId flag to the streaming pipeline, allowing users to customize ID handling while maintaining backward compatibility by default. The implementation involved propagating the new setting through both the OpenAiStreamingChatModel and OpenAiStreamingResponseBuilder, utilizing Java and backend development skills. Additionally, addressed a duplicate tool call ID issue in streaming responses, resulting in cleaner and more predictable UI behavior. The changes improved the reliability of streaming flows and established a foundation for more flexible ID management in future updates.