During December 2025, Mateusz Junkier focused on reliability and test stability improvements in the nrfconnect/sdk-zephyr repository. He addressed two critical bugs by enhancing the robustness of the device flashing process and normalizing test paths for Kconfig tracing. Using Python scripting and embedded systems expertise, Mateusz introduced a dynamic timeout mechanism for serial-port flashing, reducing flakiness and debugging overhead. He also made test path validation repository-agnostic, improving consistency across different environments. While the work did not involve new feature development, it demonstrated depth in diagnosing and resolving complex issues, ultimately contributing to more stable CI pipelines and predictable device bring-up.