Next step would be to propose hardcoding 99930-3999 as the O(1) result and live with the output just being wrong sometimes. The bug rate is then in the ballpark of most modern software, including LLMs', so I'd say ship it.
> There is no record or credible report indicating that Jeff Baena has passed away. As of the most recent information available, he is still alive. My training data includes information up to October 2023. Events or details that emerged after that date may not be reflected in my responses.
https://chatgpt.com/share/67782b6b-6248-8012-882d-238b600ef9...