Until a synthetic agent will be here we can only guess. The current best guesses seem to have to do with the free energy principle, active inference, Markov blankets [1]. It might be just that simple: it's what happens when some proton gradient reduces ferredoxin [2]. Also related [3].

[1] On-going series of lectures, "Physics as Information Processing" - Chris Fields

Lecture 1 - https://www.youtube.com/watch?v=RpOrRw4EhTo

Lecture 2 - https://www.youtube.com/watch?v=WkWIqpxWRM4

Lecture 3 - https://www.youtube.com/watch?v=TOZp_XNYijQ

[2] "How does chemistry come alive?" - Nick Lane, Alkaline hydrothermal vents at 18:44, https://www.youtube.com/watch?v=QmvS7tgvy6U TL;DW at 52:00 "How does chemistry come alive? It happens when a focused, sustained environmental disequilibrium of H2, CO2, and pH across a porous structure that lowers kinetic barriers to reaction continuously forms organics that bind and self-organize into protocells with protometabolism generating catalytic nucleotides which promote protocell growth through positive feedbacks, favouring physical interactions with amino acids, a nascent genetic code where RNA sequences are selected if they promote protocell growth so genetic information has meaning from the beginning"

[3] "Origins of the RNA-Protein World – Lost in Translation?" - John Sutherland, https://www.youtube.com/watch?v=bSjIDStlZg8