Tekumara contributed to the openai/codex repository by addressing a critical sandbox policy issue that blocked numpy usage within secure environments. Focusing on sandbox security and system configuration, Tekumara modified the seatbelt base policy to permit reading the hw.physicalcpu property, which was necessary for numpy imports to function correctly inside the sandbox. This targeted bug fix restored parity between sandboxed and host behaviors, enabling reliable numpy-dependent data processing and testing workflows. The work, implemented using the Seatbelt Policy Language, reduced the need for workarounds and improved the stability of experimentation in secure contexts, demonstrating depth in low-level policy configuration.