What Is Reality Really Made Of?

We present a coalgebraic framework from which fundamental physics emerges. The entire construction rests on a single definition: $\Omega$ is the final coalgebra for the endofunctor $F(X) = \mathbb{Z}_3 \times X^3$ in the category $\mathbb{Z}_3$-Set. From this, we derive: (i) spacetime as the srs graph ($z=3$, $g=10$); (ii) orbital invariants encoding particle properties; (iii) explicit formulas for charge ($Q = \varepsilon E/3$), spin ($s = \delta + 1/2$), and the fine-structure constant ($\alpha^{-1} = 137.035999$, deviation $0.07$ ppm from experiment); (iv) a Lagrangian recovering the Schrödinger, Dirac, Klein-Gordon, and Einstein-Hilbert equations. No free parameters are introduced. Further articles will provide complete proofs and testable predictions.