[BUG] Bun crash on Windows 11 ARM64: panic "incorrect alignment"

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?

Bug Description

Claude Code VSCode extension crashes immediately on Windows 11 ARM64 with a Bun runtime panic. This has been happening consistently for the past 2 days. The extension is completely unusable.

Environment

• OS: Windows 11 Home ARM64 (10.0.26200)
• CPU: ARM64 (neon fp aes crc32 atomics)
• RAM: 16.76GB
• VSCode Extension: anthropic.claude-code v2.1.49 (win32-arm64)
• Bun Version: v1.3.10 (bundled with extension)

Error Log

What Should Happen?

Claude Code should start normally without crashing. The extension panel should open and be usable.

Error Messages/Logs

Bun v1.3.10 (1423d3c8) Windows arm64
Windows v.win11_dt
CPU: neon fp aes crc32 atomics

panic(thread 21008): incorrect alignment

oh no: Bun has crashed. This indicates a bug in Bun, not your code.

https://bun.report/1.3.10/W_11423d3cmgkgEugogCwmzrfwl0uiBgyvBw32CwmvBo7xB44wCwvhgmCw236lC4i16lCg6xjkBgsjufCYKERNEL32.DLLg0jCCSntdll.dlloqi1BA0eNrLzEvOLypKTS5RSMzJTM/LTc0rAQBMcwep

Error from Claude: Error: Claude Code process exited with code 3

Steps to Reproduce

1. Install Claude Code extension v2.1.49 on Windows 11 ARM64 device
2. Open any project in VSCode
3. Open the Claude Code panel
4. Extension crashes immediately on startup with Bun panic

Note: No win32-x64 build exists on the marketplace as a workaround.
Upgrading the bundled Bun version may resolve the ARM64 alignment issue.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.49 (worked until ~Feb 20, 2026)

Claude Code Version

2.1.49 (win32-arm64)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

• Device: Windows 11 ARM64 (Snapdragon/ARM processor)
• RAM: 16.76GB
• Bun version bundled: v1.3.10
• Bun crash report: https://bun.report/1.3.10/W_11423d3cmgkgEugogCwmzrfwl0uiBgyvBw32CwmvBo7xB44wCwvhgmCw236lC4i16lCg6xjkBgsjufCYKERNEL32.DLLg0jCCSntdll.dlloqi1BA0eNrLzEvOLypKTS5RSMzJTM/LTc0rAQBMcwep
• No win32-x64 build available on marketplace as workaround
• The crash is in Bun's memory alignment on ARM64, not in Claude Code's logic