Even though it's Puccini, the SF Opera has run Il Trittico (the triptych) only twice before Wednesday night's opening. And for the first time on this stage, the same soprano, Patricia Racette, is singing the lead in all the three one-act pieces, a rare feat since they are all so varied: the first one is drenched in tragic realism, the second one in religious transcendence and the last one is a rubicund farce of stolen heritage. The same baritone, Paolo Gavanelli, is also singing the male lead in all pieces, scoring the middle point on a technicality, since it's an all nun affair in a convent.