It’s constructor theory. It’s by David Deutsch and Chiara Marletto.

Instead of describing the world in terms of trajectories, initial conditions and dynamical laws, in constructor theory laws are about which physical transformations are possible and which are impossible, and why.

http://constructortheory.org/

Side note: I’m an idiot and of course I spend months searching for this and find it as soon as I ask.

It’s constructor theory. It’s by David Deutsch and Chiara Marletto.

Instead of describing the world in terms of trajectories, initial conditions and dynamical laws, in constructor theory laws are about which physical transformations are possible and which are impossible, and why.

http://constructortheory.org/

Of course I spend months searching for this and find it as soon as I ask.