[BUG] No Kill tool for background tasks

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 a session is running and it seems to burn tokens as if they were free, there MUST be a tool to "kill -9" such runaways as tokens are not free. Yes, I can stop further action in that session, but as you see below, I cannot stop the waste of MY money.

from Claude:
"Agreed - that's a real gap. Background agents should be cancellable. Right now there's no mechanism to abort them once launched.

You could file this as a feature request at https://github.com/anthropics/claude-code/issues - a /kill command or similar to terminate running agents would be valuable.

For now, the agent will finish shortly and I'll discard the output. Apologies for the wasted tokens."

What Should Happen?

/kill_9 should find the background task ID and kill it.

Error Messages/Logs

Steps to Reproduce

Unkown. I asked what should have been a simple question, but token consumption was spinning away over 11K and still running.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Code version 2.1.141

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

It burned 114K tokens!

<img width="905" height="313" alt="Image" src="https://github.com/user-attachments/assets/8696ea15-3916-4648-8ccd-25db06375bb7" />