Claude Code Chrome integration fails to connect when Claude Desktop (Cowork) is also installed

[ch-804]

Description

Claude Code's Chrome browser integration (tabs_context_mcp) never connects when Claude Desktop is also installed
with the Cowork/browser feature enabled. The extension remains in a disconnected state even with Claude Desktop fully
closed.

Environment

• Claude Code version: 2.1.59
• Extension version: 1.0.56
• Extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn
• OS: macOS (Darwin 25.3.0)
• Chrome: latest

Root Cause (Investigated)

Both Claude Desktop and Claude Code register native messaging hosts for the same extension ID:

• com.anthropic.claude_browser_extension → /Applications/Claude.app/Contents/Helpers/chrome-native-host
• com.anthropic.claude_code_browser_extension → ~/.claude/chrome/chrome-native-host

Claude Desktop force-installs the extension via Chrome's External Extensions policy (~/Library/Application Support/Google/Chrome/External Extensions/fcoeoabgfenejglbffodgkkbkcdhcgfn.json), causing Chrome to label it "Added
by a third-party". The extension's service worker opens the Desktop Cowork side panel UI but never initiates a
connection to Claude Code's native host.

Steps to Reproduce

1. Install Claude Desktop with Cowork/browser integration enabled
2. Install Claude Code and set up Chrome integration
3. Close Claude Desktop completely
4. Attempt to use Claude Code's Chrome tools — connection always fails

What Was Tried

• Full Chrome restarts (multiple)
• Removing and reinstalling the extension
• Verified native messaging host config is correct with matching extension ID
• Verified Claude Code binary is functional (native host creates socket successfully)
• Verified account match (same email in Claude Code auth and claude.ai in Chrome)
• Temporarily hiding Desktop's native messaging host file — did not resolve it

Expected Behavior

Claude Code's Chrome integration should work independently of whether Claude Desktop is installed.

Actual Behavior

tabs_context_mcp always returns: "Browser extension is not connected"

The extension only opens the Desktop Cowork side panel UI and does not connect to Claude Code's native messaging host.

[enkr1]

Still experiencing this on macOS (Darwin 25.3.0, Chrome latest). tabs_context_mcp returns "Browser extension is not connected" consistently. Been broken for days. Any update on a fix? @anthropics/claude-code

[alennugi]

Environment: macOS, Chrome with multiple profiles (Default + Profile 2, 7, 9, 10, 11, 12), Claude Desktop (Cowork mode)

Debugging session findings:

1. chrome-native-host process starts successfully (PID visible in Activity Monitor) — Chrome ↔ native messaging host communication works
2. The bridge from native host → Cowork VM is broken — tabs_context_mcp always returns "not connected"
3. com.anthropic.claude_code_browser_extension.json and com.anthropic.claude_browser_extension.json both reference the same extension ID (fcoeoabgfenejglbffodgkkbkcdhcgfn), causing conflicts when both are active
4. External Extensions policy (~/Library/Application Support/Google/Chrome/External Extensions/) force-installs the extension into ALL Chrome profiles — previous cleanup commands targeting only Default profile had no effect
5. No Playwright/Puppeteer/Chromium processes running — no external automation conflict
6. Full reinstall of Chrome + Claude Desktop + clearing all caches did not fix the issue (Chrome Sync restores extension state)
7. Disabling External Extensions + re-authorizing extension + restarting Chrome — still fails

Conclusion: The native messaging host starts but cannot establish the socket connection back to the Cowork VM. This appears to be the same regression from the Feb 2026 Claude Desktop update.