[BUG] [REGRESSION] Claude Code no longer allows for additional headersHelper on oauth MCP servers

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?

In version v2.1.101, a major change was including per the changelog:

Fixed the /mcp menu offering OAuth-specific actions for MCP servers configured with headersHelper; Reconnect is now offered instead to re-invoke the helper script

This was actually a feature, not a bug, because it allowed for forwarding additional headers to MCP Proxy servers such as LiteLLM and still allowed for usage of the native Oauth2 servers. Without this functionality, we can no longer use the MCP Proxy feature of LiteLLM properly since the "Authenticate" option has been removed. This should be restored to allow for custom headers to be forwarded in addition to oauth

What Should Happen?

I should be able to Authenticate/Re-authenticate an OAuth MCP server as well as have a custom headersHelper that sends additional needed headers.

Error Messages/Logs

Steps to Reproduce

1. Create an entry such as the following in your ~/.claude.json under .mcpHeaders:

"time": {
    "headersHelper": "/Users/dennis.henry/fetch-mcp-headers.sh",
    "type": "http",
    "url": "https://litellm.host.here/time/mcp"
  }

1. And add a ~/fetch-mcp-headers.sh with the following content:

#!/bin/sh
TOKEN="$(op item get 'litellm-api-key')"
printf '{"x-litellm-api-key":"Bearer %s"}\n' "$TOKEN" 

1. Start claude code and type /mcp
2. Navigate to time MCP and hit Enter
3. Note no Authenticate or Re-Authenticate option, just Connect

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

1.1.100

Claude Code Version

1.1.101

Platform

AWS Bedrock

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_