I can see how to do this (Gif 1 of 3):
But I need a mitred corner. At a corner this tight wrt to the radius, Rhino - understandably, I guess - doesn’t know what is intended without additional definition. Wondering if there’s a way to provide that without adding an extra step? (Gif 2 of 3)
Ensuring both paths extend beyond the curve’s radius provides Rhino with enough definition, but it then requires a trimming step in most cases. Maybe there’s a more efficient way?