Developed customizable HTTP headers support for multimodal content downloads in the jd-opensource/xllm repository, focusing on enhancing flexibility and compliance in data transfer workflows. The implementation introduced a global configuration flag for default headers and enabled per-request header overrides, updating both the protocol buffers and downloader logic to support these features. Comprehensive unit tests were created to validate header parsing and merging, ensuring correctness and safety in header configurations. The work leveraged C++, CMake, and Protocol Buffers, with an emphasis on maintainable code and clear documentation. Collaboration and traceability were maintained through detailed pull requests and commit history throughout the development process.