When ChatGPT launched, Stack Overflow faced a cataclysmic shift: developer behavior was changing overnight. In this episode, Teresa Torres talks with Ellen Brandenburger, former product leader at Stack Overflow, about how her team navigated the disruption, prototyped AI features, and eventually built an entirely new business line. Ellen shares the inside story of Overflow AI—from the first scrappy prototypes of conversational search, through multiple iterations with semantic search and RAG, to the tough decision to roll the product back when it couldn’t meet developer standards. She also explains how Stack Overflow turned a looming threat into opportunity by creating technical benchmarks and licensing its Q&A corpus to AI labs. This episode offers a rare look at what it really takes to adapt when a platform-defining shift hits—and what product managers, designers, and engineers can learn about prototyping, evaluating quality, and building in uncertainty.