Windows: Chrome extension connection broken in 2.1.37, works in 2.1.19 (EADDRINUSE pipe conflict)

Environment

• OS: Windows 11
• Claude Code broken version: 2.1.37
• Claude Code working version: 2.1.19
• Chrome extension: Claude in Chrome (Beta) v1.0.47
• Node.js: v22.17.0

Description

Chrome extension integration fails to connect on Windows in version 2.1.37. Downgrading to 2.1.19 immediately resolves the issue — the extension connects and tabs_context_mcp returns tab data normally.

Error

When running the native host manually or when Chrome spawns it, it fails with:

[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Creating socket listener: \.\pipe\claude-mcp-browser-bridge-klein
[Claude Chrome Native Host] Socket server error: Error: listen EADDRINUSE: address already in use \.\pipe\claude-mcp-browser-bridge-klein

The --claude-in-chrome-mcp process and --chrome-native-host process both run, but they never establish a connection. tabs_context_mcp always returns "Browser extension is not connected."

Steps to Reproduce

1. Install Claude Code 2.1.37 on Windows
2. Install Claude in Chrome extension v1.0.47
3. Run claude --chrome
4. Extension shows "Status: Enabled, Extension: Installed" in /chrome
5. Any browser tool call returns "Browser extension is not connected"
6. Manually running the native host shows EADDRINUSE on the named pipe

Workaround

npm install -g @anthropic-ai/claude-code@2.1.19
claude --chrome

Extension connects immediately on 2.1.19.

Regression Window

Broken in 2.1.37, working in 2.1.19. The exact version where it broke is somewhere in between.

Related Issues

• #21363
• #22885