Building Pi, and what makes self-modifying software so fascinating

Brought to You By: • Statsig — ⁠ The unified platform for flags, analytics, experiments, and more. • Sonar – The makers of SonarQube, the industry standard for automated code review • WorkOS – Everything you need to make your app enterprise ready. — Mario Zechner is the creator of Pi, a minimalist, self-modifying AI coding agent, that is the foundation upon which OpenClaw (created by Peter Steinberger) is built. Meanwhile, Armin Ronacher is the creator of Flask, and a longtime user of Pi. The pair are also friends. I sat down with Mario and Armin for the latest episode of the Pragmatic Engineer Podcast for an interesting conversation about AI and their reservations about it – even though both are heavily invested in building AI-powered tools. Mario explains why he built Pi, and gives his take on why it has become so popular. Armin walks us through how he uses AI tools, including building a game with Pi, and why he always puts human judgment firmly at the heart of his approach. We cover the risks of over-automation, the limits of agentic workflows, and why strong engineers with informed judgment still matter. We also get into the challenges of working with code written by non-engineers, and whether open source can withstand a tidal wave of agent-generated code. — Timestamps (00:00) Intro (07:30) How Mario, Armin, and Peter Steinberger met(15:15) How 30 dev teams use AI agents: learnings (21:50) The importance of judgment (24:26) Challenges when non-engineers write code (28:30) Downsides of over-automation (32:18) Pi (48:09) OpenClaw + Pi (50:54) “Clankers” (57:32) Open source and AI (1:00:22) Complexity as the enemy (1:02:50) Building an AI-native startup (1:11:52) “Slow the F down” (1:16:40) MCPs vs. CLI (1:25:03) Predictions and staying up to date — The Pragmatic Engineer deepdives relevant for this episode: • The impact of AI on software engineers in 2026: key trends • Cycles of disruption in the tech industry • The AI engineering stack • The creator of OpenClaw: "I ship code that I don't read" • What is inference engineering? Deepdive — Production and marketing by ⁠⁠⁠⁠⁠⁠⁠⁠ https://penname.co/⁠⁠⁠⁠⁠⁠⁠⁠ . For inquiries about sponsoring the podcast, email podcast@pragmaticengineer.com. Get full access to The Pragmatic Engineer at newsletter.pragmaticengineer.com/subscribe