Worked on the opensearch-project/k-NN repository to address a critical bug in source filtering for derived sources, focusing on backend reliability and data integrity. Implemented a fix in Java to ensure that a field cannot be both included and excluded during source filtering, thereby preventing conflicting configurations and reducing the risk of misconfiguration in production environments. Enhanced the testing suite to include regression checks that validate non-conflicting include and exclude rules, and updated documentation to reflect the corrected filtering logic. This work emphasized backend development and testing, contributing to more robust and predictable filtering behavior within the codebase.