Cowork 403 'Request not allowed' error on Max plan - persists after cache clear and re-auth

Bug Description

Cowork feature fails with a 403 authentication error every time a task is submitted. Regular Claude Desktop chat works fine on the same account.

Error message:

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

Environment

• Plan: Max (Pro) subscriber ($200/month)
• Claude Desktop version: 1.1.6679
• OS: macOS
• Network: Connected via VPN (ClashX proxy), US exit IP confirmed. API endpoint api.anthropic.com is reachable (verified with curl).

Steps to Reproduce

1. Open Claude Desktop
2. Go to Cowork tab
3. Select a project folder and submit any task
4. Immediately get 403 "Request not allowed" error

What I've Tried

• Verified Max subscription is active at claude.ai/settings
• Confirmed Claude Desktop is the latest version (1.1.6679, downloaded fresh)
• Cleared all cache: deleted Local Storage, Session Storage, Cookies, Cache, and Code Cache from ~/Library/Application Support/Claude/
• Relaunched Claude Desktop and completed fresh OAuth login
• Verified VPN connectivity: api.anthropic.com is reachable, public IP shows as US location
• Confirmed system proxy (ClashX on 127.0.0.1:7890) is correctly routing traffic
• Regular chat mode works perfectly on the same account and setup

Expected Behavior

Cowork should authenticate successfully and process tasks, just like regular chat does.

Actual Behavior

Every Cowork task submission immediately fails with 403 "Request not allowed". The error dialog offers "Try again" and "Share feedback" buttons. Clicking "Try again" produces the same error.

Notes

This appears to be the same issue reported by other Max plan users. The OAuth token is obtained and cached successfully, but the Cowork feature's API calls are rejected server-side.