He then argued that I had missed the opportunity because he had already declared his attack.

For what it's worth, he cheated. The rules quite clearly state that you have to give the person a reasonable amount of time to declare actions.

If he didn't give you any time then he's breaking the rules.

He then argued that I had missed the opportunity because he had already declared his attack.

For what it's worth, he cheated. The rules quite clearly state that you have to give the person a reasonable amount of time to declare actions.

If he didn't give you any time then he's breaking the rules.

This is a key concept when dealing with missed triggers or opportunities imo. If you are not rushing anything and even give verbal confirmations before moving between steps then I think it's entirely fine to not mention/allow triggers that your opponent missed, but if you're pushing for them and trying to cause them by force you're a jerk.

For instance I'm okay with ignoring someone's Mara jade if after that combat (and every combat phase) I say 'dials?' and wait for confirmation. I'm not okay with ignoring it if I just start slamming down dials after ships roll their last greens.

At a tournament, I'll point out triggers they are missing or situations where they forget to add bonus dice or something like that. It's probably burnt me a few times but I think it makes for better game when both players are helping to keep track of the proper game state and reminding each other of potential missed opportunities before they are missed.

There is a difference between reminding an opponent of a mandatory effect like range bonuses or Rebel Captive and reminding them of optional things like firing with a certain ship or doing an action.

I get that. I'll remind my opponent of all of those things regardless. I'm happy to take advantage of my opponents' tactical mistakes but prefer to help them avoid making procedural ones.

Yeah, I have to agree with the mandatory effect vs discretionary effect breakdown. If something like Rebel Captive or Mara Jade is going to automatically give me stress, I do it myself. If they do something like forget to declare an action or forget to use one of their optional rerolls when they rolled terribly, I generally wait until they are finished the turn and then say "Next time don't forget you have X that lets you do Y".

Wouldn't have told him to boost, as it's not my job to fly his list. I do the same with upgrade bonuses, etc (of course, half the time I forget to use these myself, and I don't mind them not reminding me). Like others have said, I would probably say something after the round (in a nice way).

I would remind them to roll the correct amount of dice, etc. Fly casual, but carry a big lightsaber. Or something. (We do learn more by mistakes than letting them slide, and we probably better prepare newer players by insisting on rules in tournaments--casual matches are different.)

Usually I put all my face up damage cards away, then I help my opponent take all his undamaged ships off the play area and put them back into his carry case.

Like others, I try not to suggest what actions/maneuvers my opponent should choose, but I will sometimes question actions that seem really odd (like taking an Evade with no ability to benefit from it and the ship cannot be shot at). If someone is forgetting an ability like Gunner, Lone Wolf, FCS, ect, or forgets to take an action, I will usually remind them of it.

Granted, I have not played against a "win at all costs" X-Wing player yet, so my mood would likely change if playing against someone like that.

He then argued that I had missed the opportunity because he had already declared his attack.

For what it's worth, he cheated. The rules quite clearly state that you have to give the person a reasonable amount of time to declare actions.

If he didn't give you any time then he's breaking the rules.

Oh, I threatened to call the TO over so he relented. I knew he was trying to cheat.

It depends on the tournament. Here would be my responses to someone who (in my mind) clearly bumps but doesn't think they did.

Casual play with friends - "Ok, that's cool"

Store tournament - "hmm..I think you bumped, but that's cool"

Store championship - "I think you bumped, roll off?"

Regionals - "I think you bumped, let's get a judge and maybe agree to a roll off?"

World's - "JUDGE!"

I apply this attitude to other aspects like forgetting an action, take backs, etc.