Guillaume developed end-to-end background task support for the jlowin/fastmcp repository, enabling context propagation and authentication for distributed workers. He implemented Redis-backed notification queues and progress tracking, replacing polling with blocking operations to improve efficiency and reliability. His work included enhancing the Context class to propagate request identifiers and restore access tokens from Redis, ensuring secure background execution. In the modelcontextprotocol/python-sdk, Guillaume added icon theme support for light and dark modes, improving UI adaptability. He rewrote tests as integration tests using Python and async programming, increasing coverage and reducing brittleness, which deepened the reliability of background task workflows.