And how does the reorientation of the collective project take place

Not for me to decide.

Generally speaking, ideas of "socialism" do not consist of utopian templates to be imposed willy-nilly upon the world without its permission.  Socialism isn't a George W. Bush game of "I'd rather be dictator."  This, besides the critique of capitalism given in "Capital," is the revolution in socialist thinking that was promoted by Marx and Engels.  Leaders such as Stalin and Mao chose a different path because the conditions they faced were impossibly inappropriate to the propaganda they used to promote their regimes.

who then decides how well the "free producers" are following the goal of ecological integrity?

Ecosocialism presumes general social approval of the goal of avoiding ecological collapse.  Modern capitalist society, on the other hand, heedlessly transforms the world into parking lots, lawns, buildings, and monoculture farms while waiting for ecological collapse to educate it toward a better way -- or more likely to kill it outright.

"Imagine all the people/ Sharing all the world" -- John Lennon