Claude in Chrome: browser extension not connected despite extension showing Connected status

Bug description

claude --chrome MCP tools consistently return "Browser extension is not connected" despite the Chrome extension popup showing "Connected" status. Tried 20+ connection attempts in a single session — same error every time.

Environment

• Claude Code version: 2.1.39
• OS: macOS 26.2 (Build 25C56), arm64
• Chrome version: 144.0.7559.133
• Node: N/A (native install)
• Shell: zsh

Steps to reproduce

1. Launch claude --chrome from terminal
2. Open Chrome with Claude in Chrome extension installed
3. Extension popup shows "Connected" status
4. Call tabs_context_mcp with createIfEmpty: true
5. Returns: "Browser extension is not connected"
6. Call switch_browser — same error
7. Repeated 20+ times — always same result

Diagnostic details

Process state

claude --chrome  (PID 27738, running)
Chrome 144.0.7559.133 (multiple helper processes running)

Port scan

Checked ports 55243, 12333, 3456, 8765, 9222 — no MCP server listening on any port.

MCP configuration

• claude mcp list shows "No MCP servers configured"
• claude mcp add claude-in-chrome ... returns "this name is reserved"
• Adding under alternate name chrome-browser did not resolve the issue

Settings files

• ~/.claude/settings.json — no MCP config
• Project .claude/settings.local.json — no MCP config
• MCP tools are visible in the tool list (indicating built-in registration via --chrome flag) but connection fails

Expected behavior

tabs_context_mcp should connect to Chrome and return tab information when the extension shows "Connected" status.

Actual behavior

Every MCP tool call returns the same error:

Browser extension is not connected. Please ensure the Claude browser extension is installed 
and running (https://claude.ai/chrome), and that you are logged into claude.ai with the 
same account as Claude Code.

Additional context

• The extension was toggled off/on in chrome://extensions
• Chrome was fully restarted
• The extension popup consistently shows "Connected"
• lsof -i -P | grep chrome shows no listening ports from Chrome extension
• This blocks visual verification of code changes in a development workflow