Ovinomancer
No flips for you!
You seem to have missed the point. The ability to announce an action isn't agency. That's what @pemerton said. So asking if games exist where you are prevented from announcing actions doesn't counter that argument -- whether you are or not, announcing actions isn't agency. Being able to announce actions for other characters (which can happen in D&D, legally, by the rules) doesn't refute that announcing the action still isn't agency.Are there no RPG's that prevent you from announcing your characters action under certain circumstances? Are there none that ever give the ability to announce an action for your character to another player or NPC?
You seem to have confused "ability" with "agency". I have the ability to announce actions. True. This gives me agency. False. The ability to announce actions is necessary, but not sufficient, for agency to exist. It's like you've found a car engine and say, aha, this is what makes the car go. At first glance, this seems reasonable. But, you also need gasoline. You also need someone to provide control of the engine. You also need a car to put the engine in. The engine is necessary to make a car go, but it is not sufficient by itself. This is the same for declaring actions for a character in play. Necessary, not sufficient.