[BUG] /terminal-setup command on Zed deletes user config without any warnings

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 using the new /terminal-setup command on zed, Claude Codes deleter user keymap config and replaces with the setting for creating a new line with Shift+Enter

  {
    "context": "Terminal",
    "bindings": {
      "shift-enter": ["terminal::SendText", "\^[\r"],
    },
  }

Currently it silently creates a .bak file. There is no warning or indication to the user that their keymaps config was modified.

This can be very problematic as Zed allows you to add multiple keymaps on different modes, in particular for vim modes, when you could replicate leader keymaps (e.g. https://gist.github.com/oca159/0b480ed6555056418905b6e59af33674)

What Should Happen?

There is two options:

• Add the new kepmap at the bottom
• Inform the user that the file has been modified and he should verify the new config.

Error Messages/Logs

Steps to Reproduce

• Enter Claude on Zed
• Run /terminal-setup

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.0.74

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

_No response_