Certified Commitment Horizons in Dynamic Lot Sizing: Prefix Stability, Inverse Shortest Paths and One-Step Calibration of Forecast Revisions

Unrefereed candidate manuscript and reproducible evidence package. The release defines a weighted commitment radius for prefix stability in the classical Wagner–Whitin dynamic lot-sizing model, derives exact floor-aware tie radii against fixed competing paths, and provides a polynomial frozen-comparator lower certificate. Exact rational software, deterministic witnesses, adversarial tests, benchmarks, a pinned environment, a 30-page manuscript and machine-readable assurance records are archived together. Producer-side replay and GitHub Actions pass; this is not independent reproduction, formal verification, conventional peer review, operational validation, or a secured novelty determination. The illustrative UCI case uses reconstructed forecast vintages and stylised costs. Original manuscript and documentation content are CC0-1.0, original code is MIT, and the bundled UCI dataset remains CC BY 4.0.