Anderson commanded all the army facilities in the Charleston area. That included Fort Sumter.
The Confederacy was in Negotiations with the U.S. when Capt. Anderson moved his troops under the dark of night out to Ft. Sumter (a nonviolent act of Aggression) and then the U.S. tried to reinforce the fort by ship.
There was no confederacy when Anderson moved his men to Sumter, only South Carolina had announced secession. Likewise there was no agreement preventing Anderson's move. Buchanan had agreed not to reinforce if the South Carolina forces agreed not to take over any federal property, and agreement they themselves violated by seizing Moultrie, Castle Pinkney, and the Charleson armory. Since the agreement had been violated, Buchanan's actions in trying to resupply and reinforce Sumter broke no agreement.
Yes the Feds were looking for a fight and provoked the South till it had no choice.
How did they provoke? They took no hostile actions, fired on no South Carolina targets, did not interfere with shipping in to and out of Charleston? What form did this provocation take?
It still could have ended right their, but Lincoln called for 75,000 volunteers, and then invaded the sovereign borders of Virginia.
That's like saying it could have ended there but Roosevelt had to declare war over Pearl Harbor.