Claude Managed Agents dynamic workflows hit public beta: the lead agent writes an orchestration program running up to 64 concurrent threads and 1,000 agents per run

Anthropic expanded dynamic workflows in Claude Managed Agents to public beta. Instead of delegating to subagents one by one, the lead agent writes a workflow program that the server runs in the background as a workflow run, organized in phases that fan out agents, pass results between them, loop until a review passes, and handle failures. Agents can be defined inline or picked from workflows.predefined_agents, and all share the session sandbox. Documented limits: 64 threads working at once per run, 1,000 agents per run lifetime, 24h default lifetime, 10 open runs per session. Runs have no separate price; thread tokens count toward the session budget. Enable via multiagent.type multiagent_20261001 with workflows enabled.