What
When another Claude Code session sends a message while you're working, it now appears with contextual framing that helps Claude understand the message source.
Details
- Messages from peer sessions are labeled: "A peer session sent a message while you were working"
- Claude is instructed: "This is from another Claude session, not your user. After completing your current task, decide whether/how to respond."
Evidence
Peer session notification framing (search for "A peer session sent a message")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.