Worked on modernizing the build infrastructure for the risc0/zirgen repository by upgrading the Rust toolchain to version 1.83. This involved updating toolchain configuration files and making minor compatibility adjustments to ensure stable builds with the latest Rust features. The work also included enforcing license header compliance across all source files, reducing licensing risk and aligning with current best practices. Focused on build system configuration and code maintenance, the changes improved security, maintainability, and access to new language capabilities. The approach emphasized careful validation of build compatibility, ensuring that the repository remained stable and reliable throughout the upgrade process.