finally done...makes a difference if you make a stupid fatal error along the way.
no green. Thought it would be tough until I spotted a pair in a square.
EZPZ. It didn't have any of the usual Medium tricks with virtuals. But it did have an example of what I call "distributed elimination," where two cells must be the same, and two numbers were forbidden in one of them and another number was forbidden in the second. So the fourth number went into both.