Who decides what to produce in a price system?

pretty sure its the sellers?

but sorta not the sellers? they just sell it.

this isnt too in depth of a question though.

so its sorta the sellers and buyers both decide in a way, cause price signaling?

In a purely fixed price system, the government decides what will be produced and in what quantity.
In a purely free price system, these questions are decided solely by the market.

Disclaimer: I don't recall the technical definition of price system