/doctor reports phantom "npm-global" install when npm prefix shares ~/.local/bin with native installer

Description

/doctor flags my native install as a duplicate npm-global install. Both rows in the warning point to the same path (the native installer's symlink), and npm -g uninstall @anthropic-ai/claude-code is a no-op because there is no npm package — only the native binary.

Diagnostics output

⚠ Multiple installations found
├ npm-global at /Users/me/.local/bin/claude
└ native     at /Users/me/.local/bin/claude

⚠ Leftover npm global installation at /Users/me/.local/bin/claude
  └ Run: npm -g uninstall @anthropic-ai/claude-code

Environment

• macOS (Darwin 25.4.0), zsh
• Claude Code 2.1.131, installMethod: "native", autoUpdates: false
• npm config get prefix → /Users/me/.local ← so npm's global-bin dir is /Users/me/.local/bin/
• readlink ~/.local/bin/claude → /Users/me/.local/share/claude/versions/2.1.131 (native install target)
• npm ls -g @anthropic-ai/claude-code → empty
• ~/.local/lib/node_modules/@anthropic-ai/ does not exist

Root cause (best guess)

The detector appears to treat "binary present in \\$(npm config get prefix)/bin\" as proof of an npm install. When a user's npm prefix happens to be ~/.local (a common XDG-ish layout), it collides with the native installer's symlink directory and produces a false positive.

Suggested fix

Before declaring a binary an npm install, verify the symlink target is under node_modules/@anthropic-ai/.... If readlink resolves to ~/.local/share/claude/versions/<v>/, classify as native regardless of which directory the symlink itself sits in.

Reproduction

npm config set prefix ~/.local
# install Claude Code via the native installer (drops symlink at ~/.local/bin/claude)
claude
> /doctor

Workaround

Move npm prefix off ~/.local (npm config set prefix ~/.npm-global + PATH update). Otherwise harmless — the native install works correctly.