[BUG] Claude in Chrome: --claude-in-chrome-mcp crashes on startup with TypeError (Spread syntax requires iterable)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report
• [x] I am using the latest version of Claude Code

What's Wrong?

The --claude-in-chrome-mcp subprocess crashes immediately on startup with TypeError: Spread syntax requires ...iterable not be null or undefined, preventing the Chrome extension from ever connecting to Claude Code CLI.

The native messaging host starts fine and creates its socket, but the MCP bridge process crashes before it can connect — so tabs_context_mcp always returns "Browser extension is not connected."

What Should Happen?

The MCP bridge process should start without crashing and connect to the native messaging host socket, allowing the Chrome extension to communicate with Claude Code CLI.

Error Messages/Logs

TypeError: Spread syntax requires ...iterable not be null or undefined
      at <anonymous> (/$bunfs/root/claude:694:1548)
      at <anonymous> (/$bunfs/root/claude:11:1011)
      at <anonymous> (/$bunfs/root/claude:1825:512)
      at <anonymous> (/$bunfs/root/claude:11:1011)
      at <anonymous> (/$bunfs/root/claude:2596:2404)
      at <anonymous> (/$bunfs/root/claude:11:1011)
      at <anonymous> (/$bunfs/root/claude:4814:9627)
      at <anonymous> (/$bunfs/root/claude:11:1011)
      at <anonymous> (/$bunfs/root/claude:4814:14370)
      at <anonymous> (/$bunfs/root/claude:11:1011)

Bun v1.3.10 (macOS arm64)

Steps to Reproduce

1. Install Claude Code v2.1.50 on macOS arm64
2. Install the Claude in Chrome extension
3. Start a Claude Code CLI session in any terminal
4. Run /chrome to enable the Chrome extension
5. Any mcp__claude-in-chrome__* tool call returns "Browser extension is not connected"
6. To see the actual crash, manually run the MCP server:

``bash
~/.local/share/claude/versions/2.1.50 --claude-in-chrome-mcp &>/tmp/chrome-mcp-debug.log &
sleep 2 && cat /tmp/chrome-mcp-debug.log
``

1. The TypeError crash is in the output

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

2.1.50 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

• Terminal: Ghostty
• macOS: 15.6 (Build 24G84)
• Architecture: arm64 (Apple Silicon)
• Bun: 1.3.10
• Native messaging host (chrome-native-host) starts correctly and creates its socket at /tmp/claude-mcp-browser-bridge-<user>/<pid>.sock
• Native messaging host config (com.anthropic.claude_browser_extension.json) correctly points to ~/.claude/chrome/chrome-native-host
• Chrome spawns the native host on extension load (confirmed via ps aux)
• The crash happens in the MCP server process itself, not the native host
• No other Claude processes (Claude Desktop, Conductor) were running at time of reproduction
• Previously had Claude Desktop installed which had overwritten the native messaging host config (separate known issue) — fixed that, but the MCP server crash is independent