[BUG] Claude in Chrome v1.0.66 — not connected in Cowork mode despite native host running (macOS, April 2026)

Description

Claude in Chrome extension v1.0.66 (updated April 2, 2026) fails to connect to Claude Desktop Cowork mode. The extension shows CSP (Content Security Policy) errors blocking inline scripts in options.html. All individual components work correctly — the extension is installed and enabled, the native messaging host process is running, and the user is signed in — but Cowork MCP tools (tabs_context_mcp, switch_browser, etc.) consistently return "Browser extension is not connected."

Environment

• OS: macOS (MacBook Pro)
• Chrome: Latest stable (April 2026)
• Extension: Claude in Chrome (Beta) v1.0.66
• Extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn
• Claude Desktop: Latest version (Cowork mode)

Steps to Reproduce

1. Open Chrome with Claude in Chrome extension v1.0.66 installed and enabled
2. Sign in to extension with valid Anthropic account
3. Open Claude Desktop in Cowork mode
4. Attempt to use any Claude in Chrome MCP tool (e.g. tabs_context_mcp, switch_browser)
5. Result: "Browser extension is not connected"

Diagnostic Results

Native Messaging Host: Running correctly

ps aux | grep chrome-native-host
thanakorns 4483 /Applications/Claude.app/Contents/Helpers/chrome-native-host chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/

No Claude Code CLI conflict: Only com.anthropic.claude_browser_extension.json exists in NativeMessagingHosts directory.

Extension Errors (from chrome://extensions):

Executing inline script violates the following Content Security Policy directive
script-src self. Hash: sha256-kFwyFWA0myfqRcE5y2d5UX8g0o2QFHSmCz1gWSW0xpk=

Context: options.html:8 (anonymous function)

What was tried (all failed)

• Cleared Chrome cache and cookies
• Signed out/in to extension
• Toggled extension off/on
• Removed and reinstalled from Chrome Web Store
• Killed all processes, restarted in correct order
• Verified native host process running
• Attempted switch_browser MCP command multiple times

Suggested Fix

Move the inline script in options.html/sidepanel.html to an external .js file, or add the script hash to the CSP in manifest.json.

Related Issues

• #41879 #24982 #34331 #21699 #20690