Kostas Papageorgiou enhanced log schema validation in the panther_analysis_tool repository by expanding support for YAML test file formats. He implemented logic in Python to recognize both _tests.yaml and _tests.yml suffixes, ensuring consistent discovery and validation of schema test files. By introducing targeted test fixtures and improving schema validation coverage, Kostas strengthened the tool’s ability to catch configuration errors early and improved the reliability of data quality checks. His work focused on backend development, schema validation, and testing, resulting in a more robust feedback loop for developers and enabling faster detection of issues across varying YAML schema formats.