[BUG] & (background) shortcut sends text as regular message instead of spawning background task

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?

The & prefix shortcut (documented as "& for background" in the help screen) does not work. Instead of spawning a background task, the text after & is sent as a regular message to the conversation.

For example, typing & test should launch a background agent with the prompt "test", but instead it arrives as plain text in the chat.

What Should Happen?

The & prefix should intercept the input and spawn a background task with the remaining text as the prompt.

Error Messages/Logs

No error messages. The input is silently treated as a regular message.

Steps to Reproduce

1. Open Claude Code CLI
2. Type & test and press Enter
3. Observe that the message is sent as regular text instead of being processed as a background task
4. The assistant receives "& test" as a plain user message

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

2.1.96 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

The help screen (visible at the bottom of the CLI) correctly lists & for background as a shortcut, but the feature does not activate when used.