[BUG] Cowork 403 "Request not allowed" on Pro plan

Preflight Checklist

• [ ] 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?

• Plan: Claude Pro Account
• Error: Failed to authenticate. API Error: 403 {"error":{"type":"forbidden","message":"Request not allowed"}}
• Chat mode works fine, only Cowork fails
• Claude Desktop version: latest
• Network: proxy confirmed working (api.anthropic.com reachable)
• Claude Code /status shows: Login method: Claude Pro Account, Proxy set correctly

What Should Happen?

Cowork should authenticate successfully and allow task submission, just like Chat mode does on the same account. Currently, every task submitted in Cowork returns a 403 "Request not allowed" error immediately, while Chat mode works perfectly fine.

Error Messages/Logs

Steps to Reproduce

1. Log in to Claude Desktop with a Claude Pro account
2. Switch to the Cowork tab
3. Select any project folder
4. Submit any task (e.g. "Hello")
5. Immediately receive error: Failed to authenticate. API Error: 403 {"error":{"type":"forbidden","message":"Request not allowed"}}

Note: Chat tab works perfectly fine on the same account. Claude Code CLI also works fine with the same credentials.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.98

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_