How Reddit’s designers build ultra-realistic prototypes with Figma + Cursor

With Claire Vo, Blair Metcalf · Sunday, November 1, 2026

Blair Metcalf, principal UX engineer at Reddit, discusses the architecture and impact of Reddit Proto, an internal vibe-coding harness used across Reddit's product and UX organizations. He details how the team abstracted Git, integrated live authenticated production data, and built custom Model Context Protocol (MCP) servers to map design tokens into Cursor for rapid feature prototyping and automated engineering handoffs.

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Key takeaways

Blair Metcalf built an internal tool called Reddit Proto that converts visual UI annotations directly into targeted Cursor prompts. Read more →
Executives routinely kill design prototypes because static lorem ipsum feeds and mock accounts do not match their personal interests. Read more →
Reddit built Reddit Proto, a dedicated desktop application that hides Git, terminal commands, and file directories so designers and product managers can code in Cursor without technical friction. Read more →
Reddit Proto reached 100% adoption across Reddit's product and UX teams, with a company dashboard tracking over 700 active prototypes. Read more →