This is untrue. They declare their action, which includes signaling that the other side can pick up. Initiative is rolled. When the player gets his turn, he tells me what they do in the fiction, which doesn't have to be what they declared initially as things may have changed. At no point am I dictating what the PCs do. It's astounding that you could actually end up there from what I said.
You said it was
nothing more than a declaration, which is something a player says at a table in the real world. To me that sounds like you mean it has no effect on the fiction, but now you've included the detail that it "includes signaling that the other side can pick up". That's pretty vague, but it clearly means that the action declaration does establish in the fiction that the PC is "signalling" the intent to commence hostilities, i.e. action that may provoke
opposing action from the other side.
Opposition to what? He's just reaching for a sword.
Assuming the merchant wants to keep living, it establishes opposition between the PC and the merchant on which s/he's planning on using the sword.
If it's after initiative, yes. If it's before, you haven't taken a swing. You can't take the attack action, which is what a punch is, until after initiative is rolled.
Then the answer is "yes", isn't it? As a DM, you don't allow the punch-swinging character's arms to move until after initiative has been rolled, and that's fine for your games. But once it's that character's turn, and s/he takes his/her swing, before the attack hits or misses, there's a moment in which the swing is in process and the character is attacking. That moment can be established in the fiction before rolling initiative in my games. All I'm concerned with happening after initiative is the
resolution of the attack, the hit or the miss. I believe that initiative exists as a mechanic to tell us the order in which events are resolved, not when they're initiated.
No it doesn't. It presents them in the context of determining order of turns. It explicitly says this. It's the first line for God's sake, "Initiative determines the order of turns during combat."
It's the "during combat" that gives you the context that initiative takes place in a situation where sides in a conflict are opposing one another.
Nothing to do. Conservation of resources. I don't agree with attacking these people. Other reasons. Opposing the enemy hasn't ever been a consideration when I decide to do nothing.
Forgive me if that doesn't sound like a very interesting battle. Why isn't there anything to do, and why are you in a battle with people you don't want to attack?
Opposition doesn't happen(and then only possibly) until someone takes the first action. Before that, when one or both sides do something to cause the perception if imminent combat, you determine surprise, then establish positions, then roll initiative. It's a pretty lame order as far as I'm concerned. If you don't know the positions, you can't really determine surprise, but whatever. That's the order they pick. Once initiative has been rolled and people start taking actions, they can opt to take actions that pull them into opposition, like attacking or grappling. Or they can take an action that doesn't involve opposition, like searching for an object, drinking a potion, casting a spell that doesn't oppose anything, moving and stopping and much much more!!
It's in what they do "to cause the perception of imminent combat" that I'm interested. That's what throws the sides into opposition.