[BUG] Desktop Claude Code messages stuck on "cooking" indicator - message_store_sync_blocked error (March 21, 2026)

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 Code conversations are stuck with the "cooking" indicator showing indefinitely. Messages are not being sent to the backend and disappear when returning to the
conversation.

What Should Happen?

Messages should send normally, receive AI responses, and not disappear. The "cooking" indicator should only show briefly during processing.

Error Messages/Logs

From logs (`~/Library/Logs/Claude/unknown-window.log`):
  [COMPLETION] message_store_sync_blocked
  [DESKTOP_API] Failed to get MCP server config, proceeding without MCP servers

Steps to Reproduce

1. Open Claude Code Desktop (new or existing conversation)
2. Type a message and send
3. Message shows "cooking" indicator
4. Message never completes
5. When navigating away and back, message has disappeared

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.78

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

## Additional Context

• This affects ALL new conversations (tested 4+ conversations)
• Status page shows "All Systems Operational" but issue persists
• Earlier incident today (resolved 01:42 UTC) may not be fully resolved
• Cache clearing and reinstalling did not fix the issue
• Issue occurs even with MCP servers disabled