if a FeatureScript creates a sketch, how do you get Onshape to 'realize' that it is a sketch?

In a FeatureScript, I programatically create an populate a sketch. all is well, i see my sketch, and
it is selected when i select the feature in the tree.

My sketch generates closed geometry suitable for extrusion. But when doing an extrude, I cannot select the feature, like I can a sketch.
I must instead manually select all of the entities in the sketch using the mouse.

Is it possible for me to somehow tell Onshape that the feature has created a sketch, which is suitable for selection in extrusion/sweeps?  Built-in sketches allow this.