[BUG] `claude update` falsely reports leftover npm global install when native launcher is in npm global prefix directory

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 update reports a leftover npm global installation even when @anthropic-ai/claude-code is not installed via npm.

This appears to happen when the native Claude Code launcher is installed at ~/.local/bin/claude and npm's global prefix is also ~/.local. Claude Code seems to classify the launcher path as npm-global based on the npm prefix/bin directory, even though the actual launcher is the native install symlink.

Verified local state:

~/.local/bin/claude -> ~/.local/share/claude/versions/2.1.128

The npm global package is absent:

npm list -g --depth=0 @anthropic-ai/claude-code
# empty / not installed

Running the suggested cleanup command is a no-op:

npm -g uninstall @anthropic-ai/claude-code
# up to date

### What Should Happen?

If `@anthropic-ai/claude-code` is not installed in the npm global package tree, `claude update` should not report a leftover npm global installation.

It should recognize the launcher as native when:

```text
~/.local/bin/claude -> ~/.local/share/claude/versions/<version>

### Error Messages/Logs

```shell
$ claude update
Current version: 2.1.128
Checking for updates to latest version...

Warning: Multiple installations found
- npm-global at /home/<user>/.local/bin/claude
- native at /home/<user>/.local/bin/claude (currently running)

Warning: Leftover npm global installation at /home/<user>/.local/bin/claude
Fix: Run: npm -g uninstall @anthropic-ai/claude-code
Claude Code is up to date (2.1.128)

$ npm -g uninstall @anthropic-ai/claude-code

up to date in 123ms

Steps to Reproduce

1. Install Claude Code using the recommended native installer:

``bash
curl -fsSL https://claude.ai/install.sh | bash
``

1. Use an npm global prefix that resolves to ~/.local:

``bash
npm prefix -g
# /home/<user>/.local
``

1. Verify the Claude launcher is native:

``bash
ls -l ~/.local/bin/claude
# ~/.local/bin/claude -> ~/.local/share/claude/versions/2.1.128
``

1. Verify the deprecated npm package is not installed:

``bash
npm list -g --depth=0 @anthropic-ai/claude-code
# empty / not installed
``

1. Run:

``bash
claude update
``

1. Observe that Claude Code reports both npm-global and native at the same launcher path and recommends npm -g uninstall @anthropic-ai/claude-code, even though the npm package is already absent.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

Unknown

Claude Code Version

2.1.128 (Claude Code)

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

The warning disappears if npm's prefix is overridden for the command:

NPM_CONFIG_PREFIX="$HOME/.npm-global" claude update

That suggests the detection is based on npm global prefix/path overlap rather than actual npm package presence.

Impact: this does not block updates, but it creates a persistent misleading warning and recommends a cleanup command that cannot resolve the issue.