Arnez developed GDB arch15 record/replay support for s390 in the espressif/binutils-gdb repository, focusing on enabling precise state capture and replay for modern z/Architecture targets. He implemented opcode handlers for bit manipulation, arithmetic, and vector operations in C, integrating them with GDB’s internal record/replay mechanisms. This work enhanced debugging fidelity and reproducibility, allowing developers to more effectively analyze and reproduce complex or intermittent issues on s390 systems. Arnez demonstrated strong skills in low-level programming, embedded systems, and debugging tools, delivering a feature that reduces time-to-root-cause and supports robust performance analysis for advanced mainframe workloads.