Yeah, I guess it’s not so bad for the datasucker case (where the successful run on archives is replaced with a successful run on HQ, but there is still a single “successful run” trigger).
It gets a little dodgy to me with sec testing – looking at the “conditional abilities” in the rules reference, I think that the explanation for what happens comes from
If the trigger condition of a conditional ability is met by a
specific timing structure of the game (for example, “When
your turn begins…”) and that timing structure becomes invalid
between the trigger condition being met and the ability
triggering, then the triggered ability never triggers and does
not resolve. A timing structure becomes invalidated by that
structure ending prematurely, usually due to simultaneous
effects or chain reactions.
In this case, I think the interpretation is that sneakdoor’s redirect to HQ and Sec Testing’s ability are both satisfied by the successful run on Archives.
If the runner resolves sneakdoor first, then the archives sec test falls into the situation above (the “successful run on archives” trigger is no longer valid once sneakdoor replaces it). Additionally, from the “ordinal events” section of the rules reference:
When an ability refers to a specific ordinal instance of
something happening (e.g. “the first time”, “the second time”,
etc.), it refers to that instance and only that instance. If a
replacement or prevent ability happens, the game still counts it
toward the number of times the replaced or prevented event has
occurred.
if you resolve the sneakdoor first in this situation, the sec testing effect on archives will not trigger again this turn (even though it was replaced with a successful run on HQ, there has already been a successful run on Archives this turn).
In the case of sec test on archives AND hq, you are going to cause at least one of them to fizzle: either you resolve archives sec test, sneakdoor, hq sec test (in which case the HQ sec test cannot replace the “access cards” that the archives sec test already replaced) OR you resolve sneakdoor, archives sec test (fails), hq sec test.
In both cases, the “first run” on both HQ and archives has been used for the turn.
This feels a little straighter in my head, so unless anybody tells me that @3N1GM4’s response and my reading of the rules ref are bogus, I’m going to claim that I understand a thing now.
