[BUG] `claude upgrade` re-download full binrary even already latest

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 upgrade
Current version: 2.1.81
Checking for updates to latest version...
Claude Code is up to date (2.1.81)

Seems every time you run claude upgrade, it will fully re-download(as it download around 230MB of data) the binrary from the claude server, even the version is already lastest.

What Should Happen?

Check the latest version and if already latest, skip re-download.

Error Messages/Logs

-

Steps to Reproduce

1. Run cluade upgrade
2. See the network traffic it cost

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.81

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

iTerm2

Additional Information

_No response_