[BUG] Update notification still checks latest channel on stable Homebrew cask (regression from #41140)

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?

#41140 was closed as fixed in 2.1.92, but the fix is not working. I'm on 2.1.92 installed via the stable Homebrew cask (claude-code, not claude-code@latest) and still receive "Update available! Run: brew upgrade claude-code" every session. The advertised version is from the latest channel and is not available via brew upgrade.

$ claude --version
2.1.92 (Claude Code)

$ brew info --cask claude-code | head -2
==> claude-code (Claude Code): 2.1.92

$ brew outdated --cask claude-code
(no output — brew considers it current)

$ npm view @anthropic-ai/claude-code version
2.1.112

$ which claude
/opt/homebrew/bin/claude

$ ls -la $(which claude)
/opt/homebrew/bin/claude -> /opt/homebrew/Caskroom/claude-code/2.1.92/claude

The binary path is /opt/homebrew/Caskroom/claude-code/2.1.92/claude — contains claude-code not claude-code@latest, so stable channel auto-detection from the cask path should work per the fix in #41140.

autoUpdatesChannel is not set in ~/.claude/settings.json — relying on the auto-detection that 2.1.92 was supposed to add.

What Should Happen?

Update notification should check the stable channel (where 2.1.92 is current) and show no update available. It should not compare against the latest channel (2.1.112).

Steps to Reproduce

1. Install via brew install claude-code (stable cask)
2. Confirm version is 2.1.92
3. Do not set autoUpdatesChannel in settings
4. Launch claude — "Update available" banner appears referencing a version not available via brew upgrade

Claude Code Version

2.1.92

Platform

Homebrew (macOS)

Operating System

macOS Darwin 24.6.0 (arm64)

Additional Information

Regression from #41140. The comment claiming the fix shipped in 2.1.92: https://github.com/anthropics/claude-code/issues/41140#issuecomment-4254274046