[BUG] Code tab fails on every message with "u._addDefaultMeta is not a function" (Windows desktop app)

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?

Every message sent in the Code tab of the Claude desktop app on Windows fails immediately with:

Something went wrong — u._addDefaultMeta is not a function

The Chat tab in the same app works normally. Only the Code tab is affected.
This started ~2 days ago and persists across new sessions and app restarts.

Environment:

• Windows 11, build 26200.8875
• Claude Code CLI: 2.1.211 (running claude from the terminal works fine)

Tried without success:

• New session
• Full app restart (including quitting from the system tray)
• npm install -g @anthropic-ai/claude-code (installed 2.1.211, no change)

Note: the CLI installed via npm works, so this appears to be the app's bundled Code component, not the CLI.

What Should Happen?

Messages sent in the Code tab should be processed normally, as they are in the Chat tab.

Error Messages/Logs

Steps to Reproduce

1. Open the Claude desktop app on Windows
2. Click the Code tab
3. Start a new session and send any message
4. The error appears immediately: "Something went wrong — u._addDefaultMeta is not a function"

Happens on every message, in every session. The Chat tab in the same app works normally.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.211 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

Note: the Terminal/Shell field is not applicable — this issue occurs in the Code tab of the Claude desktop app, not in a terminal.