Andrey Zaitsev focused on maintainability and environment consistency across AdguardTeam repositories during September 2025. He updated the AdguardTeam/KnowledgeBase by refining documentation for the AdGuard Browser Extension MV3, clarifying rule application order and removing outdated references to Quick Fixes, using Markdown to ensure clarity for future contributors. In AdguardTeam/HostlistsRegistry, he centralized Node.js version validation by moving checks into the compose file, standardizing environment enforcement at both startup and build stages. His work leveraged JavaScript and build automation skills, addressing infrastructure and documentation needs rather than user-facing features, and demonstrated a methodical approach to repository hygiene and process improvement.