claude update fails with permission error even when npm prefix is user-owned

Bug Report

Version

2.1.77 (attempting to update to 2.1.81)

OS

macOS Darwin 25.3.0

Problem

claude update returns a permission error even though the npm prefix directories are owned by the current user (not root).

Exact Error

Warning: Insufficient permissions for auto-updates
Fix: Do one of: (1) Re-install node without sudo, or (2) Use `claude install` for native installation
New version available: 2.1.81 (current: 2.1.77)
Installing update...
Using global installation update method...
Error: Insufficient permissions to install update
Try running with sudo or fix npm permissions
Or consider using native installation with: claude install

Environment Details

npm prefix: /usr/local
owner of /usr/local/lib/node_modules: tallipszyc (user, not root)
owner of /usr/local/bin/claude: tallipszyc (user, not root)

Workaround

Running npm install -g @anthropic-ai/claude-code directly works without any permission issues.

Expected Behavior

claude update should succeed when the user owns the npm prefix directory, without requiring sudo.

Steps to Reproduce

1. Install claude-code via npm globally with user-owned prefix (/usr/local)
2. Run claude update
3. Observe permission error despite user owning all relevant directories