[BUG] Desktop app sends corrupted model name in API URL — ANSI escape codes embedded in endpoint path (404)

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?

Claude Code desktop app hangs indefinitely on every prompt ('Churning...' state). The developer console reveals the cause: the API request URL contains ANSI terminal escape codes embedded in the model name — e.g. /api/organizations/8..aude-opus-4-6[1m] instead of /api/organizations/.../claude-opus-4-6. This causes a 404 on every request, so no response ever comes back.
The CLI (claude via Terminal) works fine on the same machine with the same account. Attempted fixes that did not help: clearing ~/.claude, removing Application Support/Claude, reinstalling the app, removing all MCP plugins, updating macOS from Sequoia to Tahoe.
MacBook Air M2, macOS Tahoe, Max plan, Claude Code desktop app v2.1.87, Node 22.14.0.

What Should Happen?

The desktop app should send the correct model name (e.g. claude-opus-4-6) in API requests without ANSI escape codes. Prompts should receive responses normally.

Error Messages/Logs

/api/organizations/87870912-456d-4c13-b2f1-d76a4c47ca1f/model_configs/claude-opus-4-6[1m]:1  Failed to load resource: the server responded with a status of 404 ()
index-CkTZiI-0.js:3 [REACT_QUERY_CLIENT] QueryClient error: Co: Not found
    at wo (index-CkTZiI-0.js:2:5915)
    at index-CkTZiI-0.js:3:72562
    at async index-CkTZiI-0.js:3:73872

Steps to Reproduce

1. Open Claude Code desktop app
2. Type any prompt (e.g. 'hello' or '/doctor')
3. App shows 'Churning...' indefinitely — no response ever arrives
4. Open developer console (Cmd+Option+I) → Console tab shows 404 error with corrupted model name containing ANSI codes in the API URL

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.87

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_