[BUG] Claude Desktop Cowork hangs on "Sending request..." - path.conversation_uuid invalid UUID error

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?

Claude Desktop Cowork mode hangs indefinitely on "Sending request..." even though the backend VM spawns processes successfully.

The web log shows this error every time a Cowork task starts:
[REACT_QUERY_CLIENT] QueryClient error: Error: path.conversation_uuid: Input should be a valid UUID, invalid character: expected an optional prefix of urn:uuid: followed by [0-9a-fA-F-], found l at 1

Additionally, the log shows:
[LOCAL_SESSION] unknown sdk message type: stream_event

The backend works (processes spawn, VM connects, mounts succeed), but the frontend never displays the response.

Tried and failed:

• Fresh reinstall of Claude Desktop
• Clearing all app data (Application Support/Claude)
• Clearing Local Storage, IndexedDB, Cookies
• Fresh login
• Different folders (Dropbox, Desktop, with/without spaces in names)

Regular Chat mode works fine. Only Cowork is affected.

Claude Code Version:
Claude Desktop 1.1.351

Operating System:
macOS (Darwin 25.2.0)

What Should Happen?

Cowork should display Claude's response instead of hanging on "Sending request..."

Error Messages/Logs

2026-01-18 14:17:23 [error] [REACT_QUERY_CLIENT] QueryClient error: Error: path.conversation_uuid: Input should be a valid UUID, invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `l` at 1

  2026-01-18 14:11:51 [warn] [LOCAL_SESSION] unknown sdk message type: stream_event

Steps to Reproduce

1. Open Claude Desktop
2. Go to Cowork tab
3. Create new task
4. Select any folder
5. Send any message (e.g., "hi")
6. Observe: UI stays on "Sending request..." forever
7. Check ~/Library/Logs/Claude/claude.ai-web.log - shows UUID error

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Desktop 1.1.351 / Cowork VM SDK 2.1.8

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_