Worked on the aws-athena-query-federation repository to enhance the accuracy of query passthrough validation by refining SQL statement validation logic within DDBQueryPassthrough. Addressed a bug by replacing a broad disallowed-keywords check with a more precise rule that ensures only statements starting with SELECT are permitted, thereby reducing the risk of misclassifying valid queries. Utilized Java for backend development and leveraged AWS Lambda to support serverless execution. Demonstrated a methodical approach to SQL parsing and code refactoring, focusing on improving security and reliability for federated queries while maintaining clear commit-level traceability throughout the development process.