Anthropic has updated Claude Code to allow separate coding sessions to message each other directly, eliminating the need to manually copy context between Terminal windows. This feature, shipped in Claude Code version 2.1.224, is available for macOS and Linux but is not currently available on Windows.

The update introduces two new tools: ListAgents, which identifies other active sessions on a Mac, and SendMessage, which delivers the communication. When a session receives a message, it appears as a labeled card with a link to the sender. Crucially, only text is passed between sessions; conversation history, files, and permissions remain private and are not shared.

This functionality connects sessions a user is already running separately on their Mac, rather than sessions spawned by Claude itself. Messages between sessions on the same machine stay local and never reach Anthropic's servers. This feature sits alongside existing subagents and Agent Teams tools, providing a streamlined way for one session to warn another of breaking changes or pass along essential task updates.