Peter Eik expanded the ReactOS SDK by implementing foundational support for Intel AVX-512 extensions, focusing on future-proofing the system for advanced hardware compatibility. Working in the reactos/reactos repository, he added new AVX-512 extension definitions and aligned SDK symbols with Intel ISA documentation, ensuring a seamless path for subsequent integration. His approach emphasized low-level and system programming in C, carefully avoiding any changes to current runtime behavior while enabling future performance optimizations. The work demonstrated a methodical understanding of system architecture, laying essential groundwork for future feature development and integration without introducing instability or regressions into the existing codebase.