This work presents a covariant construction of a two-ended traversable wormhole with a finite operational tunnel and establishes its stability on every prescribed finite time interval. The model is formulated on a regular twelve-degree-of-freedom Dirac branch and combines a positive causal principal structure, global linear spectral stability, a symmetric-hyperbolic nonlinear evolution system, and persistence of the nondegenerate throat.
For sufficiently small constraint-satisfying perturbations and any fixed T<∞, the nonlinear solution remains regular on the complete two-ended spatial slice throughout [0,T]. The allowed perturbation size may depend on T. The same control guarantees that, for a finite tunnel between prescribed mouth surfaces, a future-directed timelike curve can traverse the entire bridge with a strictly subluminal speed when the chosen time interval exceeds the corresponding transit time.
The paper therefore provides a constructive example in which covariant constraint reduction, spectral stability, causal propagation, nonlinear finite-interval stability, throat persistence, and finite timelike traversability are realized within the same wormhole theory.