Claude Code v2.1.224 added the ability for sessions to message each other 1. That version was published to npm on August 7, 2026, at 01:36 UTC 2. Claude finds reachable peers with ListAgents and delivers to one by name with SendMessage 3. Per the official documentation, a message is a piece of text one Claude writes to another, never conversation history or files 3.
The receiving side has defined limits. A message from another session never counts as the user’s consent, so it cannot answer a pending permission prompt, and a command inside the message text arrives as plain text and is not executed 3. Whether an arriving message is delivered, held, or dropped is set with crossSessionInbound 3.
The feature runs on macOS and Linux and is not offered on native Windows 3. Messages to a session on the same machine travel over a per-session socket and never pass through Anthropic servers 3. The following release, v2.1.225, let SendMessage start a conversation by name with Remote Control sessions on other machines rather than only replying to them 1.
Sources
- Claude Code CHANGELOG - Anthropic official repository (v2.1.224 and v2.1.225 entries)
- @anthropic-ai/claude-code registry metadata - npm (publish timestamps per version)
- Message your other Claude Code sessions - Claude Code official documentation