Irfan Sofyana focused on backend reliability improvements for the BerriAI/litellm repository, addressing a bug in the Bedrock model integration. He refined the handling of the anthropic_beta field so it is scoped exclusively to Anthropic models, preventing errors when non-Anthropic models such as Qwen and Llama are used. Using Python, Irfan implemented targeted regression tests to ensure the field is correctly applied only to Anthropic models, including those with cross-region prefixes. His work involved API integration and unit testing, aligning integration tests with the fix to reduce the risk of model-field leakage and improve the robustness of model validation.