Forrest Smith modernized lexer infrastructure across facebook/ocamlrep, facebook/relay, and facebook/buck2 by upgrading the Logos library to version 0.15, focusing on robust token parsing and error handling in Rust. He adapted the lexer APIs to accommodate breaking changes, such as shifting from Option to Result for token output, and improved whitespace and escaped newline handling using attribute-based skipping. His work ensured cross-repository compatibility and established a foundation for future parsing features. By managing dependencies and refining error reporting, Forrest enhanced the reliability and maintainability of compiler components, demonstrating depth in dependency management, lexer development, and Rust programming.