Anthropic updates Claude Code with cross-session messaging

Anthropic has released version 2.1.224 of Claude Code, introducing a "Cross-Session-Messaging" feature for macOS and Linux users. This update allows independent Claude Code sessions running in different terminal windows to communicate with one another via plain text.

To facilitate this, the system utilizes two primary tools: ListAgents, which identifies active sessions on the machine, and SendMessage, which delivers text to a specific session. The communication is handled locally through Unix domain sockets, ensuring that messages remain on the device and are not sent to Anthropic's servers. This architecture is designed to enhance privacy by ensuring that session histories, full files, and permission settings are not transferred between sessions.

This feature aims to reduce the manual burden on developers who previously had to copy and paste context between different workstreams. While it allows for information sharing—such as alerting one session that an API interface has changed—it does not grant automatic permissions or allow one session to take control of another. Windows support and integrations for platforms like Google Agent Platform and Microsoft Foundry are currently unavailable.