[BUG] Cowork and Tahoe 26.5

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?

Your desktop app version (1.7196.0)
Your OS (macOS Tahoe 26.5)
The exact behavior (tasks stuck on "Starting up..." then endless thinking) only on cowork.
Any error messages from Console.app

What Should Happen?

Your desktop app version (1.7196.0)
Your OS (macOS Tahoe 26.5)
The exact behavior (tasks stuck on "Starting up..." then endless thinking) only on cowork.
Any error messages from Console.app

Error Messages/Logs

none never starts

Steps to Reproduce

open co work new chat or project and type anything even just "hi" it will say starting task then go to complex thinking foever it never starts. it worked just fine for the last month or so. i did recently sart getting 400 errors chat empty. now i cant use it at all.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

one before the newest

Claude Code Version

Version 1.7196.0 (2dbd78)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_