AI agent stack distilled into four parts in viral 20-minute talk

In late June 2026, a free video distilling how AI agents are built into four parts — Harness, Loop, Memory and Evals — was published and is being widely referenced among developers. The roughly 19-to-20-minute walkthrough lays out the whole picture of AI agents, and circulated amid the growing practical use of coding agents, framed around the claim that it offers the same diagram sold by expensive paid courses for free.