Worked on stability improvements and test coverage in the dealii/dealii repository, focusing on enforcing partitioner consistency within block-based systems. Addressed a bug in MGTransferMatrixFree::initialize_dof_vector by ensuring that vector and transfer partitioners remain equal, which prevents assertion failures in debug mode when differing partitioners are used. Developed an automated test to verify this behavior and guard against future regressions. The solution was implemented in C++ and leveraged expertise in the Finite Element Method, Multigrid Methods, and parallel computing. These changes improved the robustness of partitioner handling while maintaining the existing performance profile, with no regressions observed in preliminary checks.