[BUG] Desktop update breaks Cowork project-session linkage — no pre-update data protection

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?

Desktop updates break Cowork project-session linkage. After relaunch, conversation history disappears from projects. The data survives on disk — spaces.json, session JSONs with valid spaceId references, memory files, and audit logs are all intact under local-agent-mode-sessions/. The update creates new instance/account UUIDs, orphaning the previous session tree. The UI stops rendering history even though the data structure is valid. This happens on every update.

What Should Happen?

The app should automatically snapshot and migrate local session state as part of its update process. Before applying any update, snapshot spaces.json, all local_*.json session metadata, /spaces/ memory directories, .project-cache/, and audit logs. After relaunch, migrate them into the new ID hierarchy so project-session linkage is preserved. Every user who hits Relaunch should have their project continuity preserved without doing anything manually.

Error Messages/Logs

Steps to Reproduce

1. Create a Cowork project with a linked folder
2. Run one or more conversations within that project
3. Confirm conversation history appears in the project sidebar
4. Wait for a desktop update prompt and hit Relaunch
5. After relaunch, open the project — conversation history is gone
6. Verify data still exists on disk at ~/Library/Application Support/Claude/local-agent-mode-sessions/ — spaces.json and session JSONs retain correct spaceId linkage but the UI does not render them

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

claude-code 2.1.85

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_