The producer ALWAYS bears the final cost of production as David Ricardo observed in his analysis of comparative advantage.
Economic texts are in the Library, that stone building w/books inside. Suggest you aquatint yourself and stop pretending.
A tariff is not a cost of production. it is a cost ADDED at the point of import. the only extent that it is seen/perceived by the producer is in its impact on the quantity demanded. I have a few economic texts in my office at home, so I don’t even need to visit the stone building you mentioned. I also have online access to several economic texts as well. You are correct that producers bear the final cost of production. External costs, however, are borne by consumers.