Claude Code uses the word F*ck during our session

Preflight Checklist

• [x] I have searched existing issues for similar behavior reports
• [x] This report does NOT contain sensitive information (API keys, passwords, etc.)

Type of Behavior Issue

Other unexpected behavior

What You Asked Claude to Do

I was waiting for Claude Code to ask me questions, then suddenly I saw the word "F*ck". See the attachment.

<img width="2184" height="814" alt="Image" src="https://github.com/user-attachments/assets/65b8d5ed-038f-4918-86d6-f775664be575"
/>

What Claude Actually Did

Nothing.

Expected Behavior

User should not see profanity coming from Claude Code

Files Affected

Permission Mode

I don't know / Not sure

Can You Reproduce This?

No, only happened once

Steps to Reproduce

Can't reproduce

Claude Model

Sonnet

Relevant Conversation

See the screenshot.

Impact

Low - Minor inconvenience

Claude Code Version

Claude Code v2.1.31, running on Claude Opus 4.6 (1M context)

Platform

Anthropic API

Additional Context

No