Claude Code 2.1.290 adds Managed Agents onboarding and hardens plugin permissions, scheduled tasks and very large WebFetch sessions

What changed

Anthropic released Claude Code 2.1.290 at 23:33 UTC on October 5, or 07:33 on October 6 in Beijing. The release adds /claude-api managed-agents-onboard for building Managed Agents configurations from a URL or quickstart such as deep-researcher, while plugin tool.check hooks now receive agentId and the organization-required approval ceiling. It also supports partial session names for claude attach and claude logs, adds a Deny action to the sign-in approval page, and fixes silent truncation beyond 100,000 characters in WebFetch, scheduled tasks failing after resume/background handoff, Cowork cloud sessions hanging after container restarts, and several symlink/permission-boundary issues.