We give a finite-dimensional Osterwalder-Schrader reconstruction for an anisotropic Ising model on open rectangular strips and prove a spectral gap whose rate is uniform in the finite spatial extent. For temporal coupling beta, spatial coupling gamma, and parameters satisfying 0 < alpha < 1 and 2 tanh|beta| + 2 tanh|gamma| <= alpha, one number m > 0 works for every spatial length. Reflection positivity is proved directly for the Gibbs measure; the null space of the reflected form is identified with the kernel of an explicit boundary-collapse map; the OS quotient is linearly equivalent to the finite boundary-vector space; and the transfer operator forced by the site and bond forms is intertwined with a symmetrised transfer matrix.Dobrushin comparison supplies positive Perron data and a projected operator norm bounded by exp(-m) for every spatial length. Consequently, connected reconstructed correlations decay at the same common rate. Lean 4 checks thecomposition without assuming reflection positivity, Perron data, a vacuum, a gap, or clustering at the public endpoint. This replacement extends the point-slice, fixed-size v1 to finite strips with one rate uniform in spatial size. It does not construct an infinite-volume operator or Hamiltonian, provea unique particle excitation or relativistic mass shell, or claim a Yang-Mills mass gap.