All the alpha is in the remaining 20%

How does a hackathon project become infrastructure for more than 2,000 open-source repositories and reach 1.4 million monthly npm downloads? In this episode of The Merge, Hendrik Krack sits down with Simon Farshid, founder of Assistant UI, to explore what it really takes to build production-ready AI chat for AI agents. Simon explains why the visible chat window is only the surface. Behind it are streaming responses, state management, message editing, attachments, voice, interruptions, agent backends, and the level of polish users now expect from every AI product. The conversation also examines how AI coding agents are changing software engineering. When implementation becomes easier, writing clear specifications, understanding the product, reviewing edge cases, and having good taste become the real competitive advantages. As Simon puts it: “All the alpha is in the remaining 20%.” In this episode: • Why state management is the hardest part of AI chat • How Assistant UI grew from a hackathon project • The future of AI agents and generative interfaces • Why product taste is becoming an essential engineering skill • TypeScript vs. Python for building AI agents • How coding agents are creating more full-stack engineers • Simon’s automated CodeRabbit review and repair loop • How Assistant UI approaches open source and monetization • Why great engineers will lean forward instead of letting AI do everything CHAPTERS 00:00 — The 80% trap and the rise of product taste 01:19 — Meet Simon Farshid 01:56 — What is Assistant UI? 02:44 — From hackathon project to startup 03:32 — 2,000 repositories and 1.4M monthly downloads 05:28 — Why building AI chat is harder than it looks 07:23 — Designing a modular open-source product 08:43 — Why taste is the new engineering bottleneck 10:29 — TypeScript vs. Python for AI agents 13:24 — How coding agents are changing engineering teams 16:25 — Building a business around open source 20:38 — The future of AI chat and generative interfaces 23:17 — “They said chat was dead” 27:38 — Generative dashboards and new UI primitives 29:28 — The future role of software developers 30:36 — Running coding agents in a CodeRabbit review loop 34:10 — Lean forward: where the remaining 20% lives 35:57 — Rapid-fire questions Explore Assistant UI: https://www.assistant-ui.com/ Assistant UI on GitHub: https://github.com/assistant-ui/assistant-ui Try CodeRabbit: https://www.coderabbit.ai/ Subscribe for more conversations with the engineers and founders building the future of software development. #AIAgents #AIChat #AICoding