Sebastion contributed to security and performance improvements across two open-source repositories over a two-month period. For NousResearch/hermes-agent, he addressed a path traversal vulnerability in .worktreeinclude processing by implementing repository-root and worktree boundary checks, using JavaScript and file handling techniques to ensure paths remained within safe boundaries. He reinforced these changes with targeted tests to validate the new constraints, reducing security risks in build workflows. In mrdoob/three.js, Sebastion enhanced loader performance by removing legacy JSON format worker code, streamlining asset loading and simplifying maintenance. His work demonstrated depth in path manipulation, security, and front end development using JavaScript and Python.