[BUG] Native installer's Chrome native host crashes on Windows (Bun v1.3.5 assertion failure)

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 Claude Code native installer (v2.1.34) bundles Bun v1.3.5 as its JavaScript runtime. On Windows, when Chrome launches the native messaging host via chrome-native-host.bat → claude.exe --chrome-native-host, Bun hits an internal assertion failure and panics before it can handle any communication from the Chrome extension.

This completely breaks the Chrome integration (/chrome) for Windows users on the native installer. The process starts briefly and creates the named pipe before crashing, making it appear healthy in process listings. The crash only becomes visible when running the native host manually in a terminal.

claude doctor reports everything OK because it doesn't test the native host codepath.

What Should Happen?

The native host should initialize, create a named pipe, and listen for connections from the MCP server without crashing. Running claude --chrome-native-host should start a long-lived process that handles Chrome extension communication via the native messaging protocol.

Error Messages/Logs

[Claude Chrome Native Host] Initializing...
[Claude Chrome Native Host] Creating socket listener: \\.\pipe\claude-mcp-browser-bridge-{username}
============================================================
Bun v1.3.5 (1e86cebd) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2
Args: "C:\Users\{user}\.local\bin\claude.exe" "--chrome-native-host"
Features: Bun.stdin(2) jsc standalone_executable
Builtins: "bun:main" "node:buffer" "node:child_process" ...
panic(main thread): Internal assertion failure
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

Crash report: https://bun.report/1.3.5/e_11e86cebEkgggC++08F+mvBoxhkf0389e__0shkwCA0eNrzzCtJLcpLzFFILC5OLSrJzM9TSEvMzCktSgUAiSkKPg

Steps to Reproduce

1. Install Claude Code via native installer (claude install) on Windows
2. Ensure Chrome extension "Claude" is installed and enabled
3. Run /chrome in Claude Code — shows "Browser extension is not connected"
4. Test the native host directly in a terminal:

``
echo "" | claude --chrome-native-host
``

1. Observe: Bun panics with "Internal assertion failure"

Note: The npm installation (npm install -g @anthropic-ai/claude-code) which uses Node.js instead of Bun does NOT crash — the issue is specific to the bundled Bun v1.3.5 runtime on Windows.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.34

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

Workaround

Use the npm installation (npm install -g @anthropic-ai/claude-code) which uses Node.js instead of Bun. Then manually update ~/.claude/chrome/chrome-native-host.bat to point to the npm version's node.exe and cli.js instead of the native installer's claude.exe.

Environment

• OS: Windows 11
• Claude Code: 2.1.34 (native installer)
• Bun: v1.3.5 (bundled with native installer)
• Chrome extension: Claude v1.0.45
• Chrome extension ID: fcoeoabgfenejglbffodgkkbkcdhcgfn

Notes

• The process starts briefly and creates the named pipe before crashing, making it appear healthy in process listings
• The crash only becomes visible when running the native host manually in a terminal
• claude doctor reports everything OK because it doesn't test the native host codepath
• The npm version (Node.js runtime) does NOT crash — the issue is specific to Bun on Windows
• Bun crash report URL: https://bun.report/1.3.5/e_11e86cebEkgggC++08F+mvBoxhkf0389e__0shkwCA0eNrzzCtJLcpLzFFILC5OLSrJzM9TSEvMzCktSgUAiSkKPg