[BUG]

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The Chrome extension native host crashes immediately on startup with a Bun runtime panic when attempting to create
a Windows named pipe. This prevents the Claude in Chrome extension from connecting to Claude Code.

Running the native host manually shows:

[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Creating socket listener: \\.\pipe\claude-mcp-browser-bridge-MattP

panic(main thread): Internal assertion failure
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

The extension service worker console is completely blank (no logs), confirming the native host dies before any
communication.

Tested on both stable (2.1.25) and latest (2.1.37) - same crash on both versions.

What Should Happen?

The native host should start successfully and allow the Chrome extension to connect. Calling
mcp__claude-in-chrome__tabs_context_mcp should return tab information instead of "Browser extension is not
connected".

---
Error Messages/Logs

[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Creating socket listener: \\.\pipe\claude-mcp-browser-bridge-MattP
============================================================
Bun v1.3.5 (1e86cebd) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2
Args: "C:\Users\MattP\.local\bin\claude.exe" "--chrome-native-host"
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) jsc standalone_executable
Elapsed: 448ms | User: 453ms | Sys: 187ms
RSS: 0.58GB | Peak: 0.58GB | Commit: 0.58GB | Faults: 141098

panic(main thread): Internal assertion failure
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

Bun crash report: https://bun.report/1.3.5/e_11e86cebEugggC++08F+mvBoxhkf0389e__0shkwCA0eNrzzCtJLcpLzFILC5OLSrJzM9
TSEvMzCktSgUAiSkKPg

Error Messages/Logs

The native host should start successfully and allow the Chrome extension to connect. Calling
  mcp__claude-in-chrome__tabs_context_mcp should return tab information instead of "Browser extension is not
  connected".

  ---
  Error Messages/Logs

  [Claude Chrome Native Host] Initializing...
  [Claude Chrome Native Host] Creating socket listener: \\.\pipe\claude-mcp-browser-bridge-MattP
  ============================================================
  Bun v1.3.5 (1e86cebd) Windows x64 (baseline)
  Windows v.win11_dt
  CPU: sse42 avx avx2
  Args: "C:\Users\MattP\.local\bin\claude.exe" "--chrome-native-host"
  Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) jsc standalone_executable
  Elapsed: 448ms | User: 453ms | Sys: 187ms
  RSS: 0.58GB | Peak: 0.58GB | Commit: 0.58GB | Faults: 141098

  panic(main thread): Internal assertion failure
  oh no: Bun has crashed. This indicates a bug in Bun, not your code.

  Bun crash report: https://bun.report/1.3.5/e_11e86cebEugggC++08F+mvBoxhkf0389e__0shkwCA0eNrzzCtJLcpLzFILC5OLSrJzM9
  TSEvMzCktSgUAiSkKPg

Steps to Reproduce

1. Install Claude Code 2.1.37 (latest) on Windows 11
2. Install "Claude in Chrome" extension from Chrome Web Store (v1.0.47)
3. Complete extension onboarding in Chrome
4. In Claude Code, try any browser automation command
5. Receive error: "Browser extension is not connected"

To verify the crash, run manually:
echo '{"type":"ping"}' | "C:\Users\<user>\.local\bin\claude.exe" --chrome-native-host

Configuration verified as correct:

• Registry entry exists at

HKCU\Software\Google\Chrome\NativeMessagingHosts\com.anthropic.claude_code_browser_extension

• Manifest file exists and contains correct extension ID (fcoeoabgfenejglbffodgkkbkcdhcgfn)
• Batch file and claude.exe both exist at expected paths

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.25

Claude Code Version

2.1.37

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_