Gavin Williams focused on backend reliability by addressing Bedrock LLM cost estimation issues in the DataDog/dd-trace-py and dd-trace-js repositories. He improved AWS Bedrock model cost tracking by ensuring the correct model provider and model name were consistently passed to the backend estimator, reducing the risk of mispricing for customers. His work involved API integration and backend development using both Python and JavaScript, with thorough testing across 29 Bedrock models and seven vendors. By aligning backend logic and UI mapping, Gavin enhanced observability and accuracy in LLM span traces, demonstrating careful attention to cross-repository consistency and robust validation practices.