Max Shaev focused on backend development for the JetBrains/phpstorm-stubs repository, addressing stability and usability concerns in PHP stubs. During the month, he delivered a targeted bug fix for the array_filter function, ensuring it could be called without a callback by introducing a default value for the callback parameter. This change prevented potential errors and improved the robustness of PHP code relying on these stubs. Working primarily with PHP, Max demonstrated attention to detail in maintaining compatibility and reliability for developers using the stubs. The work was limited in scope but addressed a real-world issue affecting PHP backend workflows.