Ridley's Cohort said:If, for the sake of argument, you accept that Initiative does not happen until combat is possible, then there is no Surprise. The moment that the door is open, the party is presumed to be aware (or at least get their Spot checks). There is no moment in time when both the door is open and the party is automatically unaware. It is a chicken and egg problem.
This is like claiming that because an invisible character becomes visible when he attacks someone, he does not get his sneak attack damage and prevent an opponent from losing his Dex bonus if the opponent makes a Spot roll.
Surprise is surprise. Your opponents do NOT have to be in total concealment for them to surprise you.
Your definition here would force Surprise (with no chance of a Spot roll) to only occur if the opponent has total concealment.
If the rules meant that, they would have explicitly called it out.