When trouble shooting things like invalid arc commands, it would be very useful to check the G Code without actually running it.
The $C mode for GRBL will do that, but using right now is very awkward and requires low-level knowledge. Having CM support it and handle the awkwardness would be a huge win.
Yes, I know how to use it, but most people don’t, and there are weird corner cases depending on whether or not the run ended successfully or with an error.
It’s exactly the kind of thing that a computer can handle better.
This feature request has been made in the past, and there’s at least one opensource communication/control program which implements it (hashes a file, and checks a list of stored hashes, and if not present, then runs file in check mode first).
I suspect it’s a performance concern — we’ll have to see.
I didn’t mean to suggest that CM should run check mode on every file - just that check mode be available more easily, and could be used manually to trouble shoot files that are giving problems.