Feature Request: Customizable Submit Keybinding (Cmd+Return instead of Return)

Feature Request

Summary

Add support for customizable submit keybinding, specifically the ability to use Cmd+Return (⌘+Return) instead of Return to submit chat messages in interactive mode.

Motivation

Many users are accustomed to using Cmd+Return for submitting messages in chat applications (Slack, Discord, Claude Web, etc.) where Return is used for line breaks. The current behavior in Claude Code CLI where Return submits the message can be disruptive for users who frequently need multi-line inputs or are accustomed to the Cmd+Return pattern.

Proposed Solution

Add a setting in ~/.claude/settings.json to customize the submit keybinding:

{
  "submitKey": "cmd+return"  // or "return" (default)
}

Or allow more flexible keybinding configuration:

{
  "keybindings": {
    "submit": "cmd+return",
    "newline": "return"
  }
}

Current Workarounds

• Option+Enter for multi-line input (but doesn't change submit behavior)
• \ + Enter for quick escape to multi-line
• Terminal-level key remapping (complex and fragile)

Additional Context

• Current behavior: Return = submit (fixed)
• Desired behavior: Cmd+Return = submit, Return = newline (configurable)
• This would align Claude Code CLI with the behavior of Claude Web and other modern chat applications

References

• Claude Web has "Submit with Enter" toggle in settings
• Similar feature requests in other CLI chat tools have been well-received

Thank you for considering this feature request!