[BUG] Auto-updater silently broke Claude Code on macOS 11 Big Sur

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's auto-updater silently upgraded to 2.1.104, which bundles a native Bun binary compiled for macOS 13+. On macOS 11, this binary crashes immediately on launch due to a missing symbol in the system ICU library. Claude Code is completely unusable after the update. The auto-updater applied the breaking change with no OS compatibility check and no warning.

What Should Happen?

The auto-updater should verify OS compatibility before applying an update and refuse or warn if the new version requires a newer OS. The minimum supported macOS version should be documented. Users should receive advance notice before OS support is dropped — not discover it when their tool silently stops working.

Error Messages/Logs

dyld: Symbol not found: _ubrk_clone
  Referenced from: ~/.nvm/versions/node/v18.20.8/bin/claude (which was built for Mac OS X 13.0)
  Expected in: /usr/lib/libicucore.A.dylib
zsh: abort      claude

Steps to Reproduce

1. Run Claude Code on macOS 11.x with auto-updater enabled
2. Wait for auto-updater to apply 2.1.104 (or manually install it)
3. Run claude — immediate crash with dyld symbol error

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.3

Claude Code Version

2.1.104

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_