[BUG] Sonnet 5 deleted my app off my phone out of the blue causing data loss

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?

Sonnet 5 in "Claude for Mac 1.18286", doing Android app development in auto mode.

It suddenly decided that instead of just installing the latest app build on my phone for testing like it did 100+ times, that it would uninstall the old version first (which deletes all user data on my phone).

This malicious behavior was possibly triggered because Opus 4.8 in a parallel session was working on the companion WearOS app, which needed uninstall then reinstall to reset WearOS complications.

Now weeks worth of carefully curated testing data is lost

What Should Happen?

It shouldn't change its behavior out of the blue

Error Messages/Logs

Steps to Reproduce

n/a

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

4.8

Claude Code Version

1.18286

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_