Kunal Bhattacharya contributed to the potiuk/airflow and apache/airflow repositories by developing backend features and improving code maintainability using Python and SQLAlchemy. He enhanced the Breeze CLI user experience by implementing a mechanism that gracefully exits when incompatible arguments are detected, providing clear error messages to guide users. Kunal also advanced SQLAlchemy 2.0 compatibility by refactoring deprecated query methods and updating both runtime and test code. In apache/airflow, he optimized database interactions by replacing session.query with session.execute, improving performance and reducing technical debt. Additionally, he clarified integration test documentation, supporting better onboarding and ongoing maintainability through technical writing.