Developed and integrated proxy pass-through response guardrails with hooks for the BerriAI/litellm repository, focusing on enhancing backend reliability and observability. The work introduced opt-in post-call guardrails that allow success and failure hooks to be invoked after response processing, ensuring responses can be modified or logged without disrupting existing flows. Improvements included provider-agnostic error handling, enriched metadata, and defensive exception management to resolve cyclic imports. The implementation also addressed compatibility by stripping stale headers when modifying responses. Comprehensive unit testing validated guardrail behavior across edge cases. The project leveraged Python for API and backend development, emphasizing maintainability and robust test coverage.