Claude Code lets your independent sessions message each other to share findings, coordinate work, and report status without you manually copying information between terminals. Messages are delivered between tool calls and filtered through permission controls that prevent sessions from approving actions or changing configuration on each other's behalf. You can prompt Claude to send a message, or it'll detect when another session needs information and send it automatically.

• Claude Code sessions (v2.1.224+, macOS/Linux) can now message each other automatically or on request, using ListAgents/SendMessage tools, without interrupting running processes.
• Cross-machine messaging is one-way by default—remote or web sessions can only reply to existing threads, not initiate them, and replies from sessions without Remote Control arrive without a return address.
• Incoming messages are treated as system info, not user commands, so they can't approve permissions, change config, or run commands—permission prompts still trigger as normal.
• Inbound behavior is configurable per session via crossSessionInbound, with automatic naming (e.g. "myapp-3f") and /list-agents to see reachable sessions.