Claude in Chrome: Browser extension not connected after Claude Code auto-update (Windows)

Description

Claude in Chrome stopped working after Claude Code auto-updated. The extension's MCP bridge fails to connect despite all components appearing correctly configured.

Environment

• OS: Windows 11 Home 10.0.26200
• Claude Code: v2.1.150 (auto-updated 2026-05-25)
• Chrome: v148.0.7778.179
• Extension: Claude v1.0.72 (extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn)
• Native host binary: dated 2026-05-22 (1,012,560 bytes)
• Last working: 2026-05-22

Symptoms

• mcp__claude-in-chrome__tabs_context_mcp always returns "Browser extension is not connected"
• Extension works fine in its own chat UI (direct claude.ai connection)
• Chrome DevTools MCP (CDP-based) connects to Chrome without issues

Diagnostics performed

1. Native messaging host: Registry key correct at HKCU:\SOFTWARE\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_browser_extension, manifest valid (stdio type, correct allowed_origins including the extension ID)
2. Native host process: Chrome spawns chrome-native-host.exe on startup, but it shows near-zero CPU usage (0.015s) - appears idle
3. Named pipe: claude-mcp-browser-bridge-{COMPUTERNAME} exists and accepts connections (verified via PowerShell NamedPipeClientStream)
4. No enterprise policies: HKLM/HKCU:\SOFTWARE\Policies\Google\Chrome empty, no cloud management enrollment, no MDM enrollment, Chrome Local State shows azure_active_directory=0, enterprise_mdm_win=0
5. Extension permissions: manifest.json includes nativeMessaging permission
6. Console errors: v1/toolbox/shttp/mcp/<uuid> returns 405 (Method Not Allowed) - this appears to be the MCP connection endpoint being rejected server-side

Steps attempted (all failed)

• Killed and let Chrome respawn native host
• Toggled extension off/on
• Full Chrome restart (Menu > Exit)
• Completely uninstalled and reinstalled extension from Chrome Web Store
• Disabled ad blocker and Grammarly extensions
• Ran claude --chrome to attempt native host refresh
• Clicked "Reconnect Extension" from /chrome menu in Claude Code
• Closed Claude Desktop app
• Terminated remote Linux sessions
• Multiple Claude Code session restarts

Suspected root cause

Version mismatch between Claude Code (v2.1.150, updated 2026-05-25) and the native host binary (dated 2026-05-22). The --chrome flag and extension reinstall do not update the native host binary. The 405 on v1/toolbox/shttp/mcp/ suggests a protocol or endpoint change that the current native host/extension combination doesn't support.

Expected behavior

Claude Code auto-update should also update the native host binary, or at minimum the native host should remain compatible across minor version updates.