Case and choice

Solution 1:

It seems that you're looking for words for "things that happen, without your direct agency" and "things that you cause to happen by making a direct choice." No, case is definitely not the best choice for the first usage, and I think we could improve on "choice" for the second too.

I think the best choices might be as simple as event and action—something that happens vs something you do.

ACTION: I woke up early and left the house on time.
EVENT: There was a traffic jam.
ACTION: I took another route.

Why not "case" or "choice"? Well, "case" tends to mean "an instance of something"—a case of the flu, a case of mistaken identities. I wouldn't say "I got caught in traffic: I experienced a case." For "choice," while it can be used to refer to the decision made or action taken ("You sold the teddy bears; that was your choice"), it also (and more often) refers to the options facing you before making a decision ("Soup or sandwich? Your choice.").

Other possibilities:

• Decision speaks more to the action taken than "choice" does.
• If all of the "cases" are things that happen to the user, experience could be an option.
• If there's a clear implication that every "case" causes the user to take an action, you might call them stimuli (singular stimulus). (If they don't always provoke an action, though, this might be a bad choice.)