Blair Metcalf is the principal UX engineer at Reddit and the builder of Reddit Proto, the company’s in-house vibe-coding harness. With a design system MCP that maps Reddit’s product language to production code, Proto has reached 100% adoption across Reddit’s UX and product org, and more than 700 prototypes are live on it.
Listen or watch on YouTube, Spotify, or Apple Podcasts
Why Reddit built its own prototyping harness
How designers share prototypes with leadership safely
Why real Reddit data beats mock data
How one annotation becomes a code edit in Cursor
What a “feature capsule” is
Why Blair built a “Rosetta stone”
Blair’s surprising fix when AI goes sideways
Who turned out to be Reddit’s best prototypers
** Firecrawl**—Give your AI agents web data and beyond
(▶00:00) Introduction to Blair
(▶02:31) Reddit Proto demo
(▶09:15) Annotations to Cursor: the targeted edit workflow
(▶11:19) Internal deployment and adoption
(▶14:14) How leadership reviews and gives feedback
(▶15:52) Engineering handoff and the feature capsule
(▶17:50) How the custom MCP was built
(▶21:41) Quick recap
(▶24:55) Lightning round and final thoughts
• Cursor: https://www.cursor.com/
• Figma: https://www.figma.com/
• Figma MCP (Figma’s Model Context Protocol integration): https://www.figma.com/mcp-catalog/
• Code Connect (Figma’s code mapping tool): https://www.figma.com/developers/code-connect
• Gemini: https://gemini.google.com/
• ChatGPT: https://chatgpt.com/
• Vercel (referenced as inspiration for internal deploy infra): https://vercel.com/
• Reddit: https://www.reddit.com/
• Kubernetes: https://kubernetes.io/
LinkedIn: https://www.linkedin.com/in/jblairmetcalf
ChatPRD: https://www.chatprd.ai/
Website: https://clairevo.com/
LinkedIn: https://www.linkedin.com/in/clairevo/
Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email jordan@penname.co.
