A few points I want to make:
• I don't mean to actually claim that 'Lighthouse doesn't block the second-turn effects of Duration–Attacks'
is the correct interpretation of the rules—just that it's not
obviously incorrect. I think plausible arguments can be made both ways, and in fact both interpretations may be compatible with the official rules. I agree with Schneau that a rule-book clarification would probably be needed.
• This argument doesn't apply to Moat, because Moat and Lighthouse have slightly different wording as regards timing. With Lighthouse, what happens
when an Attack is played is that the Attack doesn't affect you. What happens with Moat
when an Attack is played is just that you reveal the Moat. If you do reveal the Moat, then you're told "you are unaffected by the Attack", but that clause isn't bound to any specific time.
• As a point of meta-game logic, it's certainly
desirable for Lighthouse and Moat to block attacks in the same way, but for the purposes of this discussion I'm talking about what the cards and rules
say, not what they
should say. (It would also be desirable for Throne Room and King's Court to work the same way, but that ship has sailed and I think Donald made the right call when designing King's Court.)
• The same questions arise when Attacks have while-in-play effects. Actually the rules questions might get even hairier here. Suppose Goons were "while this is in play, when you buy a card, each other player takes a –1VP token." If you Throne Room your mirror-universe Goons and I reveal Moat the first time but not the second time, do I have to take –1VP tokens when you buy a card?
• Schneau says:
I think to convince me that Lighthouse shouldn't block the next-turn affects of Armada, you'd have to convince me that the next-turn affects aren't triggered when the card is played.
I disagree. They're certainly "triggered" when the card is played; the key point is whether they "affect you" at the same time as when they're "triggered".