From G■ to E₆: Gravity Forces the Exceptional Jordan Algebra, and Dark Matter as a Pure-Gravity Singlet

We show that the minimal discrete épure is led, by gravity itself, from SO(10) to the exceptional structure E₆ / J₃(𝕆). The Jordan algebras are already present: J₂(𝕆) (dimension 10) is the Minkowski space of the SO(10) bridge, used without being named; J₃(𝕆) (the exceptional Jordan algebra, dimension 27, tied to E₆) unifies one fermion generation (16), the Higgs (the octonionic 10, identified with the programme's dilaton), and a singlet (1) in the single representation 27 = 16 ⊕ 10 ⊕ 1. The cascade stops at 𝕆 (Hurwitz) and admits both J₂ and J₃; the criterion that fixes 3×3 over 2×2 is curvature. Inertia is second-order (resistance = second derivative), as is curvature; J₂(𝕆) is flat (Minkowski) while J₃(𝕆)/𝕆P² is curved. Since the programme carries gravity (matter curves the lattice, via back-reaction), it cannot remain in the flat J₂ and must climb to J₃/E₆. The equivalence principle thereby reads structurally: inertia = gravitation = second order = J₃. With the climb forced, the singlet of the 27 exists necessarily; being neutral under SO(10)⊃SM, it interacts only gravitationally — a dark-matter candidate, possibly stabilised by the Z₃ centre of E₆. The prediction is sharp and falsifiable: dark matter is a purely gravitational singlet, not a directly detectable WIMP; a direct WIMP detection would create tension. We mark explicitly what is proper to the programme (being led to E₆ by gravity) versus inherited from E₆ physics (the dark-matter phenomenology), and that the full dynamics of the programme within J₃(𝕆) remain to be formalised.