Proof of concept

Nothing fancy. Still it already allows:

• Start/stop recording even if Recorder is in background (hold Command-Shift-5).
• Preview the editor for custom file name format in Preferences (non yet functional).
• Get recording revealed in Finder every time after recording is completed (will be a preference in the future).
• Set the custom file name format via defaults (from command line).
• Set the custom directory for saving via defaults (from command line).

Brewed ffmpeg/jq is required.