During a two-month period, Michael Boelsterli focused on backend development and unit testing within the Symfony ecosystem, contributing to both the symfony/symfony and symfony/symfony-docs repositories. He addressed two targeted bugs, first correcting the async cache computation example in the documentation to ensure proper callable behavior and interface compliance, thereby improving reliability for developers referencing the docs. In the core Symfony codebase, he implemented input validation in the Arc constructor to prevent empty place names, including a unit test for the edge case where the name is '0'. His work utilized PHP and Symfony, emphasizing code correctness and documentation accuracy.