[BUG] Claude Code - User Prompt Submit inconsistent

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?

User Prompt Submit is breaking in three different ways

a) Not applying consistently to each user prompt
b) Being applied to assistant messages
c) Being applied recursively as well (happening twice to the same user message)

Claude Code SDK version = 1.0.113

What Should Happen?

User Prompt Submit should apply consistently to just the user prompts

Error Messages/Logs

Steps to Reproduce

It's not very consistent - it's just weird behaviour with the user prompt submit hook

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.0.113

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_