Allow custom command for "Open in" setting

What variant of Codex are you using?

App

What feature would you like to see?

Similar to https://github.com/openai/codex/issues/10443

Would like to a hook to add a custom open in option. I'd imagine this would call a provided script and pass it arguments containing the file.

My use case is that I want to open in emacs, but my setup is bespoke enough that I'd like full control of how the file is actually opened (but approximately /Applications/Emacs.app/Contents/MacOS/bin/emacsclient -n -r $FILE)

Additional information

_No response_