[BUG] duplicated slash commands when scrolling

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?

When naming a slash command the same as one of the commands that ship with Claude Code, it will create duplicates when scrolling through the commands.

What Should Happen?

One custom slash command should show a single line.

Error Messages/Logs

Steps to Reproduce

1. Create a slash command named "plan" or "review".
2. Open Claude Code and scroll through the list
3. When hitting this command, duplicate line will start appearing.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.59

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

<img width="1316" height="961" alt="Image" src="https://github.com/user-attachments/assets/c5644250-3c4b-4c70-a780-faf5f35befb7" />