Andreas worked on the envoyproxy/gateway repository, focusing on enhancing HTTPS compatibility for gateway deployments. He implemented scheme header transformation to ensure correct handling of the :scheme header when proxying requests to HTTPS upstream services, addressing protocol mismatches in mixed HTTP/HTTPS environments. His approach included introducing a ClientTrafficPolicy option to control header behavior and refactoring the public API for clearer client semantics. Using Go, along with skills in API design and Kubernetes, Andreas delivered a targeted feature that reduces protocol errors and improves reliability. The work demonstrated thoughtful engineering with attention to backward compatibility and maintainability in backend systems.