Worked on the openai/codex repository to upgrade the Ollama Model Provider API, focusing on standardizing integrations by defaulting to the Responses API format. Used Rust and backend development skills to implement a version check that alerts users of legacy Ollama versions, reducing the risk of runtime format mismatches. Developed a temporary chat-format provider to bridge the transition period, ensuring backward compatibility while the old format is phased out. This approach established a clear deprecation path and enabled smoother upgrades for downstream teams, improving reliability for model provider integrations and supporting a controlled migration to the new API format.