Smarter Models Killed the Harness. Here's What's Left — Jediah Katz, SpaceXAI
Is the agent harness dead? Jediah Katz, Cursor's longest-tenured agent-harness engineer and now at SpaceX, explains why fancy harnesses no longer add coding intelligence: the data flywheel teaches models the skills harnesses used to patch in.
He then argues why the harness matters more than ever. It opens new frontiers like Grokbot, and it owns what models can't absorb: infrastructure, trust and security, and efficiency. He closes with predictions, including that 90% of agent work runs off the laptop within six months. Chapters: - 00:00 Is the harness dead? - 01:09 From prompt engineer to harness engineer - 02:02 What's inside an agent harness - 02:59 Peak harness, and the backlash - 05:00 What the research says - 06:16 The data flywheel - 07:34 The harness unlocks the next frontier - 12:07 What models can't absorb: infra, trust, efficiency - 14:21 What's next for harnesses - 17:36 Long live the harness Jediah Katz — X: https://x.com/jediahkatz | https://cursor.com Join us in SF for the second annual AIE CODE summit: https://aie.codes our last flagship summit of 2026. Applications live now!
The text is the source's own description of its publication. The content belongs to AI Engineer.
More from AI Engineer
Inside Arca's Long-Horizon Agents That Run the Business - Aman Singh, Arca
AI Engineer 23 Oct
Real AI Agent Attacks and What Would Have Stopped Them — Andrey Rybka, Bloomberg
AI Engineer 23 Oct
Outside of tech there has been no financial payoff to US companies for using AI, now viewed as a margin-hurting cost center, as VC-backed firms burn more tokens
Techmeme 4 h ago
Source: Replit recently moved most AI spend from Anthropic to OpenAI, which gave 30%+ off in a deal worth $100M+/year, after Anthropic discontinued its discount
Techmeme 6 h ago