Cross-Session Messaging in Claude Code

Claude Code sessions can now send each other a summary of what they are working on, so you do not have to re-explain a task in a second session.

One session sends the other a written summary of the task, not your conversation history and not your files
The receiving session picks the message up mid-task rather than waiting until it finishes what it is doing
Sessions find each other with a ListAgents tool and send with SendMessage, and they can reach sessions running on any of your machines
Messages sent into a session that is running with permission checks turned off are held for your approval first, while messages to normal sessions deliver automatically
Two new settings, crossSessionInbound and dialogExpiry, control that approval behavior
Shipped in Claude Code v2.1.224 for macOS and Linux including WSL 2, with no native Windows support yet