Module 4.0 — SIF v1.0 Layer 5: Bounded Anchor Reconstruction Bridge for Structural Invariant Control

This record publishes Module 4.0 MVP v1, the bounded structural repair component of the Structural Invariant Framework (SIF v1.0) Layer 5. Module 4.0 continues directly from Corpus D2 (SIF Layer 4), which identified and characterized systematic anchor-induced fragility in contradiction-aware EN→UK neural machine translation. While Corpus D2 established the failure taxonomy, Module 4.0 implements the first intervention layer: a class-aware anchor reconstruction bridge that detects, routes, and partially repairs deformations of canonical ⟨anch_*⟩ structural invariants in MarianMT-generated output. Module 4.0 is not a translation model and does not evaluate general translation quality. It operates as a post-decoding structural invariant control layer. Its output is an operational qualification decision: STRUCTURALLY_CLEAR, VERIFY_REPAIRED, REDESIGN, or REJECT. Two evaluation probes are included: a strict internal MVP probe (N=7) and a JCGM 106 real-document probe (N=10). Both yield detection_correct_rate = 1.000 and decision_appropriate_rate = 1.000. The bridge achieves anchor_precision = 1.000, anchor_recall = 1.000, and exact_match = 0.974 across 38 bridge evaluation pairs (Run 1 v3); exact reconstruction remains bounded by anchor-family coverage in the current bridge training distribution. Together, Corpus D2 and Module 4.0 close the diagnostic-to-intervention chain within SIF v1.0: D2 identifies output failure modes; Module 4.0 tests bounded repair and routing under safety constraints. Preceding record: Corpus D2 — SIF v1.0 Layer 4 — https://doi.org/10.5281/zenodo.20304841