v2.1.72 standalone Linux binary crashes with illegal instruction on Haswell (i7-4790K)

Description

Claude Code v2.1.72 standalone Linux binary crashes immediately with an illegal instruction on Intel Haswell CPUs. v2.1.71 works fine on the same machine.

Environment

• OS: Ubuntu (Linux 6.8.0-83-generic x86_64)
• CPU: Intel Core i7-4790K @ 4.00GHz (Haswell, supports SSE4.2, AVX, AVX2)
• Installation: Standalone binary via ~/.local/bin/claude symlink
• Working version: 2.1.71
• Broken version: 2.1.72

Steps to reproduce

1. Install Claude Code v2.1.72 standalone binary on a Haswell-era (4th gen Intel) system
2. Run claude --version

Actual behavior

Bun v1.3.11 (26f7d870) Linux x64 (baseline)
Linux Kernel v6.8.0 | glibc v2.39
CPU: sse42 popcnt avx avx2
Args: "claude" "--version"
Features: jsc standalone_executable 
Builtins: "bun:main" 
Elapsed: 92ms | User: 34ms | Sys: 60ms
RSS: 1.24GB | Peak: 0.19GB | Commit: 1.24GB | Faults: 0 | Machine: 33.52GB

panic(main thread): Segmentation fault at address 0x5E360A42FDC
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

Shell reports: Illegal instruction (core dumped)

Expected behavior

claude --version prints the version and exits cleanly (as it does with v2.1.71).

Workaround

Repoint the symlink back to v2.1.71:

ln -sf ~/.local/share/claude/versions/2.1.71 ~/.local/bin/claude

And disable auto-updates to prevent re-downloading 2.1.72:

// ~/.claude/settings.json
{ "autoUpdaterStatus": "disabled" }

Analysis

This appears to be a Bun runtime regression. The crash report identifies Bun v1.3.11 with the baseline x64 target, which should be compatible with Haswell. The v2.1.71 binary (which works) likely used a different Bun version. The crash is at startup before any user code runs.