What if the biggest problem in healthcare isn’t diagnosis — it’s capacity? On this episode of Building One, Tomer Cohen sits down with Dr. Thomas Kelly, co-founder and CEO of Heidi, to unpack what it actually takes to build AI for one of the most complex, regulated, and human industries in the world. Before starting Heidi, Tom was a vascular surgeon. He saw firsthand how some of the most highly trained people on the planet were spending their days on low-value administrative work. Heidi began by listening to real patient visits and drafting clinical notes. Today, it’s expanding into the vast — and invisible — work around care: follow-ups, calls, scheduling, and coordination. In this conversation, we explore: What “doubling capacity” in healthcare really means Why personalization must be nearly perfect — measured almost like a clinical SLA What it takes to build AI that doctors actually trust How GPT-4 didn’t kill Heidi’s moat — it forced a radical pivot And how Heidi rewrote the healthcare go-to-market playbook by winning clinicians one by one Everyone talks about AI’s potential. This episode is about delivering it — in the real world, where trust is fragile, stakes are high, and a 5% edit can break the magic.