Claude in Chrome: 'Browser extension is not connected' despite correct setup (macOS, Claude Desktop coexistence)

Description

Claude in Chrome consistently reports "Browser extension is not connected" despite everything being correctly configured. Both claude --chrome (terminal) and VSCode extension fail.

Environment

| Component | Version |
|---|---|
| Claude Code | v2.1.80 (npm, Homebrew node) |
| macOS | 15.7.4 (Sequoia), Apple Silicon |
| Chrome | 146.0.7680.153 |
| Node | v24.1.0 |
| Extension | v1.0.63 (fcoeoabgfenejglbffodgkkbkcdhcgfn) |
| Claude Desktop | Installed (native host config REMOVED) |

Key Observation

lsof -U | grep claude-mcp-browser shows only 1 connection (native host listening). No client ever connects to the socket. Chrome extension does not launch/connect to native messaging host.

What's Correct

• Native host config at ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.anthropic.claude_code_browser_extension.json — correct path, correct allowed_origins
• chrome-native-host script runs successfully, creates socket, logs "Socket server listening"
• Bridge socket exists: /tmp/claude-mcp-browser-bridge-zarett/*.sock
• Chrome profile account (zp28ogkc@gmail.com) matches Claude Code OAuth account
• .claude.json flags: claudeInChromeDefaultEnabled: true, cachedChromeExtensionInstalled: true, hasCompletedClaudeInChromeOnboarding: true
• Claude Desktop native host config removed (no conflict)

Steps Tried (all failed)

1. Renamed Claude Desktop native host config to .bak
2. Killed Chrome, restarted after native host config existed
3. Nuclear reset: removed ALL native host configs, deleted ~/.claude/chrome/, deleted bridge socket, uninstalled extension from Chrome, ran claude --chrome to recreate configs, reinstalled extension fresh from Chrome Web Store
4. Verified Chrome restarted AFTER config file creation (timestamp checked)
5. Tried from both terminal (claude --chrome) and VSCode extension
6. Extension has nativeMessaging permission in manifest

Additional Context

• Claude Desktop installed at /Applications/Claude.app but NOT running, native host config removed
• 8 Chrome profiles exist, extension installed on Profile 8 and Profile 21
• VSCode extension (v2.1.79) always passes --no-chrome flag — separate issue
• Extension installed on profile with matching Google account

Expected

tabs_context_mcp returns list of open Chrome tabs.

Actual

Claude in Chrome[tabs_context]
  ⎿  Tabs read

Browser extension is not connected.