Demos, feedback loops, and AI-era product judgment with Ruben Casas

Kent talks with Ruben Casas about building products again in the AI-agent era: why experienced engineers can now stay close to customers and code, how demos turn vague ideas into something people can react to, and why product judgment matters more as implementation gets cheaper.They cover Postman, MCP, agent-driven UI, prototypes, early user feedback, feature product-market fit, and the engineering guardrails that help teams ship quickly without turning the product into a pile of disconnected features.(00:00) - Introduction to Product Engineering (00:48) - Ruben Casas and Postman (07:36) - Building products again in the AI era (19:38) - Finding customer pain points (22:32) - Demos and prototypes (28:53) - Getting people to care about your ideas (31:41) - Prioritizing product problems (41:25) - Homework: build a prototype demo Ruben brings a practical perspective from building developer tooling, platform work, and AI-agent products at Postman. The conversation starts with a shift many experienced engineers are feeling right now: agents make it possible to stay involved in higher-level product decisions while also getting hands-on with implementation again. That is exciting, but it also raises the bar for deciding what is worth building in the first place.A recurring theme in the episode is that demos and prototypes are not just engineering exercises. They are product tools. Ruben and Kent talk about starting from a real pain point, building just enough to show the opportunity, putting it in front of users quickly, and using that feedback to decide whether the idea deserves more investment. They also dig into the risk of shipping too many mildly useful features, and why product engineers still need architecture, testing, taste, and guardrails as more people use AI to touch production code.HomeworkFind a real problem that is bothering you.Use an agent to build a quick prototype for it, especially if you have not tried AI coding tools seriously yet.Record a short demo, send it to someone, and ask for feedback.ResourcesRuben CasasPostmanRethinking UI in Agent-Driven SystemsMCP AppsGuest: Ruben CasasCompany: PostmanGitHub: @infoxicator𝕏: @infoxicadorHost: Kent C. DoddsWebsite: kentcdodds.com𝕏: @kentcdoddsGitHub: @kentcdoddsYouTube: Kent C. DoddsPodcast: epicproduct.engineerSee on Epic Product Engineer