During June 2025, Marcus Legendre focused on backend security enhancements for the codecentric/c4-genai-suite repository, specifically addressing a path traversal vulnerability in the REIS file upload flow. He implemented a Python-based solution that sanitizes file paths and restricts uploads to a designated temporary directory, effectively mitigating risks of arbitrary file access. Marcus reinforced these changes by adding automated tests to validate the new security controls and prevent future regressions. His work aligned with code scanning recommendations and industry best practices, demonstrating depth in backend development and security. The update improved platform safety without altering user-facing features or workflows.