[BUG] Cowork 403 "Request not allowed" on Pro plan - macOS - account not enabled

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?

What's Wrong?
Cowork fails with a 403 authentication error on every attempt. Regular Claude chat works fine on the same account.

Error Message:
Failed to authenticate. API Error: 403 {"error":{"type":"forbidden","message":"Request not allowed"}}

Steps to Reproduce:

1. Open Claude Desktop
2. Switch to Cowork tab
3. Submit any task or message
4. 403 error appears immediately

Environment:

• Plan: Claude Pro
• OS: macOS
• Claude Desktop Version: (check About Claude in menu)
• Network: VPN (ClashX Meta), system proxy configured at 127.0.0.1:7890
• api.anthropic.com is reachable and returns HTTP 200 via proxy

Troubleshooting Already Attempted:

• Verified system HTTP/HTTPS proxy is correctly set (127.0.0.1:7890)
• Confirmed api.anthropic.com is reachable via curl (HTTP 200)
• Cleared Claude Desktop cache (Cache, Code Cache, Session Storage)
• Re-authenticated after cache clear
• Regular Claude chat works perfectly on the same account and network

Expected Behavior:
Cowork should authenticate successfully and process tasks for Pro plan subscribers.

Account Email:
[liugrantted@gmail.com]

What Should Happen?

Cowork should authenticate and process tasks normally, just like regular Claude chat does on the same account.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Desktop on macOS
2. Navigate to the Cowork tab
3. Select any project folder or type any message
4. Click send / submit the task
5. Error appears immediately: 403 "Request not allowed"

Claude Model

Sonnet (default)

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.76 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_