Adrien Fillon enhanced the TLS Inspector component in the envoyproxy/envoy repository by improving observability and diagnostics for TLS handshake failures. Focusing on parseClientHello errors, Adrien implemented targeted debug logging in C++ to capture specific OpenSSL error details, enabling more effective troubleshooting of network issues. The work included introducing a new dependency to support advanced logging and instrumenting the filter’s error handling path to surface negotiation failures in logs. These changes addressed diagnosability gaps in TLS flows, allowing for faster triage and reduced resolution times, and demonstrated a focused application of C++, debugging, and network programming skills within a complex codebase.