Worked on security and reliability improvements across the ggml-org/llama.cpp and jeejeelee/vllm repositories, focusing on backend development using Python and C++. Enhanced the CORS proxy in llama.cpp by implementing header prefix sanitization, which prevents sensitive authentication headers from being forwarded, and validated the changes with both unit and end-to-end tests. Addressed a path resolution bug in vllm by ensuring local media paths are always resolved to absolute paths, improving robustness across different environments. Emphasized test-driven development with pytest and pathlib, contributing to operational reliability and codebase quality through targeted features and bug fixes within a collaborative workflow.