Anthropic AI Updates: October 4, 2026

1. Claude Code 2.1.289 Lets Mods and Plugins Spawn Teammate Agents

Anthropic. Claude Code 2.1.289, tagged on October 3, adds agent.spawn for teammates to the extension API. It also keeps one agent id across plugin hook events and reports idle and waiting states in $.agent.list(). Together these let mod and plugin authors start teammate agents and track each agent’s state from hooks, building on the mods system Anthropic introduced on October 1. Most of the rest of the release fixes permission-rule enforcement and rendering stability for mods and plugins. Source