Over a two-month period, contributed to the openai/openai-agents-python and openai/codex repositories by delivering six new features focused on backend and SDK development. Work included building a beta SDK for Sandbox Agents, enabling persistent, isolated agent workspaces with manifest and snapshot support, and enhancing model parsing for greater robustness. In openai/codex, refreshed Python SDK types, overhauled PyPI packaging, and unified versioning to streamline releases. Additionally, implemented API-key based authentication for remote exec-server registration in Rust, enforcing domain restrictions and secure credential handling. Emphasized API design, CI/CD, and testing to improve developer workflows and ensure reliable, maintainable codebases.