When adding a new task, would it be useful to type "@Whatever" and the label "Whatever" is created if it does not exist?
I feel like I want to do this all the time.
such option is already available. You can type @shopping within a task name and a label called "shopping" will be added.
Please refer to this help page for more information about labels: https://todoist.com/Help/viewLabels
Ah. It was complaining that the label didn't exist but then I esc'd out and hit return and it added the new label.