[BUG] Switching devices leads to stale prompt replay if one device has network partitioned

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

If I have a session open in Claude for Mac (Mac OS Claude 1.8555.2 (a476c3) 2026-05-22T23:04:37.000Z) and the same session opened in Claude.app (iOS), resuming Claude for Mac's session after a network partition can replay a stale prompt.

What Should Happen?

After resuming a session, Claude for Mac should recognize the current session state and not replay old prompts.

Error Messages/Logs

I don't see any obvious errors, but after resuming & replaying the stale prompt, Claude will reply "I think this is a stale message".

Steps to Reproduce

1. Start a session in Claude for Mac.
2. Join the session in Claude.app for iOS.
3. Sever the MacOS network connection.
4. Enter several prompts in iOS.
5. Wait until Claude for Mac displays a "Try Again" button to resume the session.
6. Reconnect network to MacOS.
7. Click "Try Again"
8. The session will resume, and an older prompt will appear in a new user message bubble at the end of the conversation and will submit.
9. Claude may reply that the message is stale.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Mac OS Claude 1.8555.2 (a476c3) 2026-05-22T23:04:37.000Z

Platform

Other

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_