Worked on the anza-xyz/kit repository to address a critical issue in offchain message handling by implementing strict validation for message size limits. Developed logic in TypeScript to enforce the inclusion of the v0 preamble during size checks, ensuring that oversized offchain messages are reliably rejected. Enhanced error handling and message encoding processes to maintain the integrity and reliability of offchain communications. Added comprehensive tests to verify that messages exceeding the allowed size are correctly identified and rejected. Documented the changes through a tracked changeset, contributing to the overall robustness and maintainability of the codebase during the development period.