[BUG] image-only message (no text) returns 400 messages: text content blocks must be non-empty

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?

posting an image brings up this error, and that's all well and fine, but it nukes the thread and you can't reply in it again after that. have to move to a new one and start over.

What Should Happen?

you should be able to keep working, maybe claude just responds and say hey you need text, or maybe just be able to send an image without text in the message

Error Messages/Logs

Steps to Reproduce

paste an image and hit enter without text in the message

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

idfk

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_