Observer-Independent Limiting Speed from Completed Local Events: Lorentz–Wigner–Thomas Closure

Revised version. This version clarifies the central claim that observer-independence of the limiting propagation speed is an output of the completed-event construction rather than an independent postulate. The manuscript now includes a finite discrete counting representation, in which reciprocal integer counts (p,q) yield L=p2+q2, S=2pq, and X=p2−q2, satisfying the exact finite-count identity S2+X2=L2. The distinction between the existence of a finite move-only propagation bound (an input) and the observer-independence of its measured value (a derived result) is now stated explicitly. The 3+1-dimensional construction and its Lorentz–Wigner–Thomas closure have also been clarified, together with the relation to Bondi k-calculus and standard relativistic kinematics. Minor equation, figure-caption, notation, and reference corrections are included.