[BUG] bundled avx is not running and installing avx2 on newer CPU's

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?

bundled avx is not running and installing avx2 on newer CPU's

Critical finding before I save: the latest Claude Code (2.1.150) IS the baseline Bun
build. Anthropic ships Claude Code with the baseline Bun bundled-in — confirmed via
strings: Bun v1.3.14 (Linux x64 baseline). There is no newer Claude Code version (2.1.150
IS latest). So updating system Bun won't fix Claude Code's crash; we'd need Anthropic to
ship an AVX2 build. The system-Bun upgrade is still worth doing for OpenMontage's
bun-based scripts.

Honest answer: simple for system Bun, but it won't actually fix Claude Code's crash —
because Claude Code bundles its own Bun runtime inside the 2.1.150 executable. That
bundled Bun is baseline, and you can't swap it without recompiling Claude Code. Only
Anthropic can fix that — file an issue or wait.

But yes, I'll do the system Bun reinstall now — it'll help OpenMontage's mermaid script
and any other Bun tool. Just be clear-eyed: the Claude Code session crash you saw won't
stop happening from this.

What Should Happen?

Update shipping claude with newer version of BUN

Error Messages/Logs

Bun v1.3.14 (521eedd6) Linux x64 (baseline)────────────────────────────────────────────────
Linux Kernel v6.17.0 | glibc v2.39| Reset: 4hr 1m | Cost: $29.85
CPU: sse42 popcnt avx avx2xt: [██████░░░░░░░░░░] 387k/1000k (39%)
Args: "/home/ant/.local/bin/claude" "--dangerously-skip-permissions"
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) WebSocket(13) abort_signal(26) fetch(691) jsc spawn(3247) standalone_executable process_dlopen(2) yaml_parse(709) claude_code 
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" "node:constants" "node:crypto" "node:dns" "node:events" "node:fs" "node:fs/promises" "node:http" "node:https" "node:module" "node:net" "node:os" "node:path" "node:path/posix" "node:path/win32" "node:perf_hooks" "node:process" "node:readline" "node:stream" "node:stream/consumers" "node:stream/promises" "node:string_decoder" "node:timers/promises" "node:tls" "node:tty" "node:url" "node:util" "node:vm" "node:zlib" "node:worker_threads" "ws" "node:http2" 
Elapsed: 21362314ms | User: 783974ms | Sys: 183258ms
RSS: 0.33GB | Peak: 0.73GB | Commit: 0.33GB | Faults: 1285 | Machine: 67.32GB

panic(main thread): Segmentation fault at address 0x7DAA46AB8020
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

Steps to Reproduce

Happens during rendering.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Code v2.1.150

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_