Smarter Models Killed the Harness. Here's What's Left — Jediah Katz, SpaceXAI
Smarter frontier models are making complex agent orchestration harnesses obsolete
“The shell is like the eyes and hands for the model.”
Jedidiah Katz, Cursor's longest-serving agent shell engineer (now at SpaceX post-acquisition), traces the evolution from 'prompt engineer' to 'context engineer' to 'shell engineer' and argues that increasingly capable models are collapsing the need for elaborate orchestration harnesses. Cursor's peak complexity demo involved 'Grind Swarm,' a multimodal multi-agent shell that was expensive to run, but just months later the industry—including Anthropic internally—began stripping harnesses back. The talk is a practitioner signal that the complexity ceiling for agent scaffolding may have already been hit.