Joel worked on the modelcontextprotocol/rust-sdk repository, focusing on stabilizing the Rust build process by addressing a critical compilation issue. He refactored the task_handler module to use the re-exported rmcp::serde_json path, which resolved errors for dependent crates that did not directly include serde_json. This change improved build reliability and reduced downstream friction for other developers integrating with RMCP macros. Joel applied his expertise in Rust, code refactoring, and error handling to enhance maintainability and cross-crate compatibility. Although the work centered on a single bug fix, it demonstrated careful attention to ecosystem stability and long-term codebase health.