A unique evolution law for the fine-structure constant

The position of the universe on a one-dimensional health axis obeys a law that is not chosen but forced. The forcing is stated here, not assumed. Among rational flows with a single zero at the self-dual point, poles at both window edges and odd behaviour under the window reflection, the lowest-order admissible law is unique. Its linearization at the attractor is -20000_t<0. The approach to the edge scales as (T^-t)^1/3, with a fixed exponent rather than a free parameter. The trajectory admits the implicit closed form 2_t(t-t_0)=-w^4/4+W_win^2w^2-W_win^4|w|, verified here by differentiation rather than tabulated. Carrying the full arc moves the attractor to t_f^=0.350144866454559356 and gives a present-day read ^-1(t_f^)=136.640, with the drift direction fixed at d/dt>0. The same window construction fixes the magnitude of the scalar mass parameter through an edge balance whose solution is unique, |mu_2,|=_w+N_seca^3+_F a=2423/2000. So mu_2, is an output of the sealed family rather than an input. What is not derived is stated with the result. The isolated value of _t is a clock calibration that cancels from every dimensionless prediction. The historical reading direction of the balance is retained as an informational note.