Djordy Koert enhanced boolean handling in Symfony’s serialization components, focusing on the ObjectNormalizer within the symfony/symfony and symfony/serializer repositories. He implemented robust validation logic in PHP to ensure integer representations of booleans, such as 0 and 1, are correctly filtered using FILTER_BOOL during serialization and deserialization. By expanding test coverage and refining type handling, Djordy addressed edge cases where boolean values could be misclassified, thereby improving data normalization and overall data integrity. His work leveraged object-oriented programming and unit testing to reduce misinterpretation of boolean data, resulting in more reliable API behavior and fewer downstream support issues.