Oxan refined static type definitions for mysqli usage in the phpstan/phpstan-src repository, focusing on improving PHPStan’s analysis accuracy and developer productivity. By updating the return type for mysqli_fetch_all and mysqli_result::fetch_all from a generic array to a more precise list of arrays, Oxan aligned static type hints with actual runtime behavior. This adjustment reduced false positives in static analysis and enabled safer, more accurate auto-completion for projects using mysqli. The work demonstrated a strong understanding of PHP, type hinting, and static analysis, ensuring compatibility with existing tests and usage patterns while enhancing the reliability of PHPStan’s recommendations.