Who are the protagonist and antagonist of the frame story and the "framed" story in "The Celebrated Jumping Frog of Calaveras County?"
Protagonist for the framed story would be I, correct? Antagonist for framework story would be Simon Wheeler?
In "The Celebrated Jumping Frog of Calaveras County," the framework, otherwise referred to as the narrative (how it is narrated), is how the story is told, the structure of the entire thing. This framework (called syuzhet in Russian formalism) contains the outer and inner story; that is the story of the conversation between Simon Wheeler and the narrator ("I" who is purported to be Twain himself) as well as the inner story about Smiley, the frog, and the Stranger.
Using the image of a framed picture, the outer story is the frame and the inner story is the picture, that which is "framed" by the outer story (the frame).
The protagonist of the outer (frame) story is the narrator, Twain or "I," and the antagonist is Wheeler because he duped the narrator into listening to his tale in spite of the fact that Twain didn't want to hear it. From the framed inner story, even though Wheeler is a swindler, Wheeler winds up being the protagonist who is duped by the Stranger, the antagonist.
However, an argument could be made that both Smiley and the Stranger are protagonists of the framed story. The narrator recognizes sincerity in the way Wheeler treats his tale: " . . . he regarded it as a really important matter, and admired its two heroes as men of transcendent genius in finesse." Wheeler regards each man as a hero for being able to win bets. So, protagonist, in the case of the framed story, is not necessarily the "good guy." A protagonist, for Wheeler, is a successful guy. In fact, since the Stranger swindles the swindler, he might be a better candidate for the protagonist of the inner story.