illegal hardware instruction" on Intel Core i5-3470S (Ivy Bridge, no AVX2) - crashes on startup

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?

Claude Code version: latest via npm (@anthropic-ai/claude-code)
OS: macOS
CPU: Intel(R) Core(TM) i5-3470S CPU @ 2.90GHz (Ivy Bridge, 2012)
Architecture: x86_64
AVX2 support: hw.optional.avx2_0: 0 (NO AVX2)
Node.js: v22.22.3
Terminal: zsh
iMac: Intel iMac (late 2012)

What Should Happen?

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.

Error Messages/Logs

zsh: illegal hardware instruction  claude

Steps to Reproduce

Comportamiento observado:

Primera instancia de Claude Code abierta ANTES de la actualización funcionaba
Cualquier intento de abrir Claude Code después de reinstalar falla inmediatamente
claude --version también falla con el mismo error
El binario /usr/local/bin/claude apunta a claude.exe (Bun runtime) que requiere AVX2

Pasos para reproducir:

npm install -g @anthropic-ai/claude-code
claude
Crash inmediato con "illegal hardware instruction"

Issues relacionados:

#21018
#5864
#10408

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

zsh: illegal hardware instruction claude --version

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_