During July 2025, Chengnan Cai developed Doubao LLM model support for the hacksider/trae-agent repository, focusing on backend extensibility and unified model orchestration. He introduced a dedicated client wrapper for Doubao, integrating it into the main LLM client factory to streamline onboarding of new models. His work included implementing API key and base URL initialization, chat history management, and chat completion handling with optional tool support, all using Python. By concentrating on API integration and LLM integration, Chengnan enabled smoother client experiences and improved the system’s ability to support additional models, reflecting a thoughtful, feature-driven engineering approach without reported bugs.