It's something that you come up with in advance, a plan of sorts, in preparation of an opportunity arising, such that you may capitalize on it. "Plan" is too long, however; it's not so much a plan as a simple "we quickly do X". And emphasis on quick; this is a rapid, pre-meditated move - it was come up with quickly, triggered quickly, and executed quickly. The situation arose, the action done, and then it passed. It can have had lasting consequence, or done nothing at all. It may be proactive or reactive. Maybe you don't even know why or when you'd do it, but you've prepared for it nevertheless. The effect is simple and singular, not a complex series of events. Just one thing like "everybody wearing a hat run into the basement" - potentially independent of the context that prompts the execution. It may also have a modifying context, like "if it's raining, paint one car blue" - to carry out this while it isn't raining, obviously has no effect. So it's like an instruction of sorts, waiting to be given.
What word, preferably on the short side, would describe such a thing?
'Trick' is the best I've come up with, but it has connotations of deception. Need something more straightforward.