Marc-André Lureau developed per-file Vim and Emacs modeline support for the zed-industries/zed repository, enabling users to specify editor configurations directly within source files. He implemented safe, bounded modeline parsing by restricting reads to the first and last kilobyte of each file, and used Rust’s Arc to efficiently manage ModelineSettings without unnecessary cloning. This work focused on editor development and language parsing, laying the groundwork for future mode-to-language mapping and broader configurability. By updating documentation and collaborating with other contributors, Marc-André delivered a well-integrated feature that enhances onboarding and editor usability, demonstrating depth in configuration management and parsing performance.