[BUG] Conversations created on Desktop app not syncing to Web/Mobile — same account

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?

I started a conversation on the Claude Desktop app and continued it over several days. The conversation displays and works normally on Desktop, but it does not appear at all on the Claude mobile app, even though I’m signed in with the same account on all devices. I searched both inside and outside Projects on mobile and found no trace of the conversation.
This appears related to existing reports: anthropics/claude-code#81658 and anthropics/claude-code#58477

What Should Happen?

I travel frequently and rely on accessing conversations started on my laptop from my mobile device. This sync failure is preventing me from using Claude reliably as a daily work tool, and is a factor in whether I renew my subscription.

Error Messages/Logs

Steps to Reproduce

1. Sign in to the same Anthropic account on both Claude Desktop app and Claude mobile app (or claude.ai web).
2. Start a new conversation on the Claude Desktop app and send several messages over multiple days.
3. Open the Claude mobile app (or claude.ai web) signed in with the same account.
4. Search for the conversation using both "recent chats" and keyword search — inside and outside any Projects.
5. Expected: the conversation should appear and sync normally across devices.
6. Actual: the conversation does not appear at all on mobile/web, even though it displays and works normally on Desktop.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Sonnet 5

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_