[BUG] [JetBrains] Invalid beta flag error when using Opus 4.6 (1M context) model

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?

When selecting "Opus 4.6 (1M context)" model in the JetBrains plugin,
every request fails with a 400 error due to an invalid beta flag (double comma ,,).

What Should Happen?

Switching to "Opus 4.6" (without 1M context) works fine.

Error Messages/Logs

API Error: 400 {"error":{"message":"invalid beta                                                                                                                                                                              
     flag,,betas:claude-code-20250219,interleaved-thinking-2025-05-14,redact-thinking-2026-02-12,context-management-2025-06-27,effort-2025-11-24","type":"invalid_request_error","param":null,"code":"internal_error"}}

Steps to Reproduce

1. Open JetBrains IDE with Claude Code plugin installed
2. Select model: "Opus 4.6 (1M context)"
3. Send any message

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

0.1.14-beta

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PyCharm terminal

Additional Information

_No response_