Decoupling the Brain from the Hands: Claude Managed Agents (Part 1 of 4) — Anthropic

The first version of Claude Managed Agents put everything in one container. Here's why Anthropic split it apart. NEXT UP: AI ENGINEER CODE SUMMIT Join us in SF for the second annual AIE CODE Summit, Nov 10–12, our last flagship summit of 2026. Applications live now: https://aie.codes Priyanka Phatak, who leads the Claude Managed Agents engineering team at Anthropic, defines an agent as a model in a loop with tools, plus a harness and a sandbox, and explains why harnesses encode assumptions that go stale with each new model. She walks through the first architecture, where the session, harness and sandbox shared one hard-to-debug 'pet' container, and the redesign into an append-only session log, a brain (harness plus Claude) and hands (sandboxes and tools). Credentials stay out of the sandbox and time to first token dropped about 90%. Then she introduces the core APIs with a simple joke-teller agent. This is part 1 of 4 of the Claude Managed Agents workshop from Anthropic. In this video: • Why harnesses carry model-specific assumptions • Decoupling session, harness and sandbox into replaceable parts • Injecting credentials at an egress proxy so Claude never sees them • The core flow: environment, agent, session, events SPEAKERS Priyanka Phatak, Member of Technical Staff, Anthropic (leads the Claude Managed Agents engineering team) Gabe Cemaj, Member of Technical Staff, Anthropic GitHub: https://github.com/gcemaj LINKS Claude Managed Agents docs: https://platform.claude.com/docs/en/managed-agents/overview Scaling Managed Agents: Decoupling the brain from the hands: https://www.anthropic.com/engineering/managed-agents CHAPTERS 0:00 Welcome and intros 0:58 Workshop agenda 2:05 What makes an agent work 3:06 Harnesses and model assumptions 4:16 Sandboxes and limiting blast radius 5:10 First architecture: all in one container 6:05 The pet vs cattle problem 7:45 Decoupling the brain from the hands 9:05 Keeping credentials out of the sandbox 9:49 Flexible compaction, faster first token 10:49 One brain, many hands 11:09 Interfaces outlast assumptions 11:39 Claiming API credits 12:24 Q&A: the three core interfaces 13:49 Building a joke-teller agent 15:18 Sessions and the event stream 16:33 Console quick start Recorded at the AI Engineer World's Fair 2026 in San Francisco. Subscribe for more talks from the engineers building with AI. AI Engineer: https://ai.engineer YouTube: https://www.youtube.com/@aiDotEngineer X: https://x.com/aiDotEngineer LinkedIn: https://www.linkedin.com/company/aidotengineer/ #Claude #AIAgents #AIEngineer