By my reading of (a), we need to read (b) as "if the trigger never occurs [later in the round]".
I find this interesting, because each of us has read this and thought it was natural, but have come to different conclusions.
Our confusion may be because of different ways to see what a "round" is.
Not sure, but I think you are thinking of ROUND = starts with the turn of the highest-init creature, ends after the turn of the lowest-init creature.
The others are thinking of ROUND = one interval between any 2 consecutive turns of the same creature (provided it doesn't change init) OR starts at any init number, ends at the same init number next time. Sort of a "moving window".
The problem is, the designers themselves get confused all the time, some of them think in the 1st way, others in the 2nd.
The text under Combat -> The combat sequence -> The round, seems to support your view, but the
Ready an Action mechanic is
IMHO clearly meant to work for cyclic initiative. It makes little sense that the lowest-init character cannot ready any action, which would be the result of the 1st interpreretation.
With the 2nd interpretation (which I'm using) you don't really get 2 action per rounds. More precisely, you
do get 2 actions in "round 5" if you seen rounds your way, but you still get as many attacks as everyone else during the battle, which is what matters, because you delayed the first attack.
In some cases, readying has an edge. Ours was such case, because they just happened to be lucky that the first foe entering the inner cave was immediately before them in initiative term (but clearly, it could have been Aeiyan and they would not have any benefit). However, the price they paid was that they actually wasted a lot of turns, when they were waiting for the trigger, while they could have attacked.
It also means you are focused and can't do opportunity attacks, etc., when an action is readied. So in those two ways it seems a good rule (over previous editions).
This is actually not explicitly mentioned in the current packet.
It would make sense that while readying you cannot take other reactions.
However, it would also make sense that you could, but in that case obviously you lose the readied action because you're taking another reaction and you can only take one per turn.
I thought the whole idea of the Reaction was to enable an extra triggered action per round.
Using the ready action creates another use for your reaction just like any other.
Both of view propose an original view, which IIRC leads to the same conclusions as mine, but it's a bit gamist and thus more complicated
I just see "Readying" as a mechanic very much grounded in
narrative: it represents someone waiting/delaying a little bit.
Note that currently the rules are restrictive about what actions you can delay: "attack, grapple, hustle, knock down, or use an item". It sounds like a specific list, and doesn't include spells (although some spells can be cast as reactions, therefore IMO here the rules should be more explicit).
Anyway, the Ready an Action rule clearly doesn't want to allow you anything more than you could normally do in the course of one "moving window" round, i.e. 1 action + 1 move + 1 reaction. Actually, it lets you do
less, because technically the Readying itself costs your action and your attack costs your reaction (you can still move before Readying), while if you attack normally at your init, you still have your reaction for later.
