Nonzero-Anchor Continuation and Cancellation-Preserving Bounds in a Lorentzian Simplicial Model

We continue two identified stationary branches of a fixed boundary-capped Lorentziansimplicial action using actual nonzero-anchor coordinates and cancellation-preserving derivativeenclosures. The source retains nine four-simplices, eighteen independently varied Lorentz links,moving boundary returns, and all 114 stationary equations. A regular bordered solve with anunscaled kernel constraint supplies a full source chart around an actual root; its explicit inversehas no division by the deformation parameter. Exact scalar, coordinate, and residual-row identitiesretain the off-shell Hessian connection and parameter drift. On a two-disk parameter domain, signedcomplex-disk Taylor coefficients and complete noncommuting matrix-function tails give usableoriginal-action derivative bounds. The complete constrained second response uses the actual graphborder, distinct from the averaged border of the value equation. Together with every tangent-direction cross term, these estimates close a fixed two-branch contraction on I =[b/2, 4b], whereτ = 2−61 and b = 5τ /4, with actual incoming identification on J = [3τ /4, b]. The error is lessthan 4.685406× 10−20 relative to the exact source-defined predictor p(t)=xB +(t− b)vB ; it isnot absolute numerical-root accuracy. The anchor retains an approximately 1.72× 10−11 locationenclosure, and no numerical exact anchor or tangent is supplied. A same-range control shows thatsigned source propagation enables the strict test even with an older downstream assembly. Thesource premises and incoming bootstrap remain explicit. No finite-section identity near t =1/64,full physical-coordinate error, or new end-to-end formalization follows. A consolidated separateAI-session review supports the stated conditional scope; its two minor corrections are adopted.Accepted returned Lean evidence covers a supporting subset, not end-to-end source formalization.