Claude in Chrome: list_connected_browsers always 'not connected' despite correct native host config (Windows 11)

Environment

• Platform: Windows 11 Pro 10.0.26200
• Claude Code CLI version: 2.1.209
• Chrome: native install, managed browser (org GPO, unrelated ExtensionSettings policy confirmed NOT blocking this extension ID)
• Extension: Claude in Chrome, installed via Chrome Web Store (fcoeoabgfenejglbffodgkkbkcdhcgfn), enabled, logged in with same account as claude CLI

Bug

mcp__claude-in-chrome__list_connected_browsers (and /chrome status) always returns:

Browser extension is not connected. Please ensure the Claude browser extension is installed and running...

Earlier in this session it also intermittently surfaced as:

Couldn't list connected browsers: JSON Parse error: Unexpected identifier "Browser"

(matches #69196 — plain-text "not connected" string apparently fed into JSON.parse() client-side)

Troubleshooting already done (all passed)

1. Extension installed, enabled, logged into levi@smart2b.nl — same account as CLI login.
2. Full Chrome restart (all chrome.exe processes killed via Task Manager, not just window close).
3. Full OS reboot.
4. Checked chrome://policy — org ExtensionSettings policy present but targets an unrelated extension ID (epolmhmpbkmljidnmbdjppnbgbhelalg, not fcoeoabgfenejglbffodgkkbkcdhcgfn) — ruled out as cause.
5. Verified native messaging host registration in registry:

• HKCU:\SOFTWARE\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_browser_extension → present
• HKCU:\SOFTWARE\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_code_browser_extension → present

1. Verified manifest JSON content for both hosts — allowed_origins correctly includes chrome-extension://fcoeoabgfenejglbffodgkkbkcdhcgfn/.
2. Verified native host binaries exist and are reachable:

• C:\Users\Levi\AppData\Roaming\Claude\ChromeNativeHost\chrome-native-host.exe — exists
• C:\Users\Levi\.claude\chrome\chrome-native-host.bat → wraps C:\Users\Levi\.local\bin\claude.exe --chrome-native-host — binary exists, claude --version returns 2.1.209 (Claude Code) successfully.

Despite every static config check passing, the runtime connection between extension and CLI never establishes. This strongly suggests the bug is in the actual stdio/native-messaging runtime handshake, not in host registration — consistent with other open Windows-specific reports (#23104, #58201, #69196, #21415, #22025, #23218).

Expected

list_connected_browsers / /chrome should detect the logged-in, enabled extension.

Actual

Always reports "not connected" regardless of extension state.