[BUG] Cowork: ALL session chat histories truncated - only last user message visible across ~1967 sessions

[teresa31033103]

Preflight Checklist

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

What's Wrong?

In the Claude Desktop app (Cowork mode, Windows Microsoft Store version), ALL session chat histories have been truncated. Approximately 1967 sessions are affected.

Symptoms:

• Only the last user message remains visible in every Cowork session
• All prior conversation history (both user and assistant messages) before that final message has disappeared from the UI
• This affects ALL sessions simultaneously, not just specific ones

Investigation findings:

• Session transcripts are still accessible via the backend API (read_transcript returns full data)
• IndexedDB LevelDB files in AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\IndexedDB still contain data (verified with strings and plyvel)
• The data is NOT physically deleted - only the UI fails to render it
• Cache clearing, app restart, and computer restart do NOT resolve the issue

Related issues: #27752, #33130, #29793, #29684, #27349

This appears to be the same IndexedDB rendering/corruption issue reported in #33130, but specifically affecting Cowork mode on Windows.

What Should Happen?

All Cowork session chat histories should display their full conversation history (all user and assistant messages) when opened in the UI, matching the data available via the backend API.

Error Messages/Logs

No specific error messages in the UI. Sessions simply show truncated history.

IndexedDB investigation confirms data exists:
- LevelDB files contain session data (verified via strings command and plyvel)
- Backend API read_transcript returns full conversation transcripts
- Custom comparator idb_cmp1 in use

Path: AppData\Local\Packages\Claude_pzs8sxrjxfjjc\LocalCache\Roaming\Claude\IndexedDB\https_claude.ai_0.indexeddb.leveldb

Steps to Reproduce

1. Open Claude Desktop app (Windows, Microsoft Store version)
2. Navigate to Cowork mode
3. Open any existing session from the sidebar
4. Observe: only the last user message is visible; all prior conversation (user + assistant messages) is missing
5. Repeat with any other session - same result across all ~1967 sessions
6. Use read_transcript API - full conversation data is returned (proving backend data is intact)
7. Inspect IndexedDB files in AppData - data exists in LevelDB binary files
8. Clear app cache, restart app, restart computer - issue persists

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

No response

Claude Code Version

Claude Desktop (Windows Microsoft Store) - Cowork mode - Claude_pzs8sxrjxfjjc

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Critical issue affecting ~1967 Cowork sessions with important AI VTuber project context.

Related issues: #27752, #33130, #29793, #29684, #27349

Root cause likely IndexedDB corruption/rendering failure (same as #33130).

Environment: Windows 11, Claude Desktop Microsoft Store (Claude_pzs8sxrjxfjjc)

[github-actions]

Found 3 possible duplicate issues:

1. Cowork: Context compaction permanently removes scrollable conversation history from UI #37273
2. Conversation history missing on resume (except last message) #24304
3. [BUG] Cowork: Minor version update permanently deletes chat history and scheduled tasks #38055

This issue will be automatically closed as a duplicate in 3 days.

• If your issue is a duplicate, please close it and 👍 the existing issue instead
• To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

[teresa31033103]

This is NOT a duplicate. Please do not auto-close this issue.

The suggested duplicates (#37273, #24304, #38055) describe different symptoms or are already closed without resolution. This issue specifically reports:

1. Cowork mode (not Claude Code CLI) session history corruption on Windows (Microsoft Store version)
2. ALL ~1967 sessions affected simultaneously - not individual session loss
3. Backend API still returns full data, confirming this is a client-side IndexedDB rendering failure, not data loss
4. Root cause analysis points to IndexedDB corruption with custom idb_cmp1 comparator (same pattern as [BUG] claude desktop-code lost after restart previous chats, cowork dont work #33130)

This is a critical data accessibility bug affecting the entire Cowork session database. The scale (1967 sessions) and the specific platform (Windows Store Claude Desktop) make this a unique report that requires engineering investigation.

Please remove the "invalid" label and assign this to the appropriate team.

[MarcusDelvecchio]

same issue

[fangmaster35]

Same, and I would add on, is there a need to truncate locally run chat history. Github Copilot and any other that i know of keeps the history of the entire chat and compacts in the background using that compaction as the point to send chat data to the cloud. Yet, the user still will be able to see the entire chat (and. information that was paid for through our token usage for reference at any point we desire to look atit )

[github-actions]

Closing for now — inactive for too long. Please open a new issue if this is still relevant.