During July 2025, Gergely Segon focused on improving template instantiation safety in the dealii/dealii repository. He addressed a subtle but critical issue by implementing a preprocessor guard that ensures DoFInvalidAccessor template instantiations only occur when the structural dimension does not exceed the space dimension. This C++ solution, leveraging advanced template metaprogramming and preprocessor directives, prevents invalid configurations at compile time and reduces downstream runtime and configuration errors. By targeting this edge case, Gergely enhanced build reliability and stability for users configuring complex DoF layouts, demonstrating a deep understanding of C++ template mechanics and robust software engineering practices.