public Geometry Sketch {get;}

// Occurs when a sketch is completed. SketchCompleted event is fired by 
//  - COTS construction tools (except annotation, dimension geometry types), 
//  - Edit Vertices, Reshape, Align Features
//  - 3rd party tools with FireSketchEvents = true
// Register for the SketchCompleted event
SketchCompletedEvent.Subscribe(sketchCompletedEventArgs
  =>
{
  // get the sketch
  var finalSketch = sketchCompletedEventArgs.Sketch;

  // do something with the sketch - audit trail perhaps
});