Worked on improving file IO reliability and data integrity in the modal-labs/modal-client repository by implementing strict data type validation for SandboxFile write operations. Used TypeScript to enforce that only Uint8Array data can be written, introducing pre-gRPC validation to catch errors before they cross service boundaries. This approach reduced the risk of data corruption and runtime failures, while also expanding test coverage to ensure robustness. Focused on front end development and testing, the work included adding unit tests to verify that invalid input types trigger appropriate errors, ultimately strengthening the reliability of file writing functionality within the codebase.