[BUG] VS Code extension: MCP cloud connector OAuth flow doesn't open browser

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 using /mcp in the VS Code extension and selecting a built-in cloud connector (e.g., "claude.ai WordPress.com"), it shows "Authentication required." Clicking to authenticate does nothing — no browser window opens and no URL is displayed to copy manually.

What Should Happen?

a browser should launch to complete the authentication process

Error Messages/Logs

nothing happens

Steps to Reproduce

Steps to reproduce

Open Claude Code in VS Code extension
Run /mcp
Select "claude.ai WordPress.com" (or any cloud connector needing auth)
Click to authenticate
Nothing happens — no browser, no URL
What I've tried

Confirmed browser launching works from VS Code terminal (open https://google.com works fine)
Cleared ~/.claude/mcp-needs-auth-cache.json and restarted VS Code
WordPress.com appears in claudeAiMcpEverConnected in ~/.claude.json
No errors visible in VS Code Output panel
CLI claude mcp has no auth subcommand to use as workaround
Environment

macOS (Darwin 25.3.0)
Claude Code via VS Code extension (not standalone CLI)
Shell: bash

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

opus 4.6

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_