adjudicator-respond.sol

// in the adjudicator contract:

function respond(State memory s1, State memory s2) public {
    // check that the first state matches the stored challenge
    assertHashMatches(s1, stored_challenge_hash);
    
    // framework checks
    assertValidSignature(s2);
    assertSameAppDefinition(s1, s2);
    assertTurnNumIncrements(s1, s2);
    // … etc.
    
    // app-specific checks
    app = NitroApp(s2.AppDefinition);
    assert(app.validTransition(s1, s2));
 
    // once all checks have passed, cancel the challenge
    cancel_challenge();
}