Scaling Managed Agents: Decoupling the brain from the hands

This post introduces Claude Managed Agents, a hosted service that decouples the agent's 'brain' (Claude and harness) from its 'hands' (sandboxes and tools) and 'session' (event log). This architectural shift addresses issues of component coupling, 'pet' infrastructure, and security vulnerabilities. Key technical contributions include: treating harnesses and sandboxes as cattle, enabling independent failure and recovery; implementing a secure security boundary by preventing direct credential access from sandboxes; using the session log as a durable, external context object for long-horizon tasks; and improving time-to-first-token (TTFT) by provisioning sandboxes only when needed, leading to significant latency reductions.