[BUG] Chrome native messaging host crashes on startup (Bun internal assertion failure) — Windows 11

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?

Environment:

• Claude Code version: bundled with Bun v1.3.11 (a2743b6d)
• OS: Windows 11 Pro 10.0.26200 (x64)
• Chrome: with Claude extension v1.0.61
• CPU: x64 with sse42, avx, avx2, avx512

Symptom:
Every call to mcp__claude-in-chrome__tabs_context_mcp returns "Browser extension is not connected". The /chrome command produces no
error but the bridge never starts.

Root cause:
The Chrome native messaging host (claude.exe --chrome-native-host) crashes immediately on startup with a Bun internal assertion failure. The named pipe \\.\pipe\claude-mcp-browser-bridge-[user] is never created, so the Chrome extension has nothing to connect to.

Reproduction:
"C:\Users\[user]\.claude\chrome\chrome-native-host.bat"

Crash output:
[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Creating socket listener: \\.\pipe\claude-mcp-browser-bridge-[user]
============================================================
Bun v1.3.11 (a2743b6d) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2 avx512
Args: "C:\Users\[user]\.local\bin\claude.exe" "--chrome-native-host"
Features: Bun.stdin(2) jsc standalone_executable
Builtins: "bun:main" "node:async_hooks" "node:buffer" "node:child_process" "node:crypto" "node:fs" "node:fs/promises" "node:net"
"node:os" "node:path" "node:process" "node:stream" "node:timers/promises" "node:url" "node:util"
Elapsed: 76ms | User: 78ms | Sys: 0ms
RSS: 0.30GB | Peak: 0.30GB | Commit: 0.42GB | Faults: 73661 | Machine: 0.14TB

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

Verified working:

• Extension installed and active in Chrome (LevelDB updated today)
• Registry native messaging host entry exists at

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

• Native host JSON config is valid, points to correct bat file
• claude.exe exists at C:\Users\[user]\.local\bin\claude.exe
• Crash is 100% reproducible, occurs every invocation

What Should Happen?

Chrome should work.

Error Messages/Logs

Steps to Reproduce

Opened Chrome

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_