Antigravity without Negative Mass: Sign-Rigidity and Loop-Induced Repulsion Analogues in Classical Physics

his preprint presents a conservative analysis of repulsion-like readouts reported in driven gravitational measurement protocols, without invoking negative mass, exotic stress–energy components, or modifications of general relativity. The work examines how non-commuting control operations, finite protocol ordering, and closed measurement cycles can produce non-null responses even when standard source-level gravitational expectations predict cancellation. The analysis is grounded in standard general relativity, weak-field limits, and driven-system kinematics, and focuses on separating genuine source-level gravitational effects from protocol-dependent measurement artifacts. A set of necessary consistency and robustness checks is presented to clarify which experimental outcomes are compatible with known physics and which interpretations are not supported. The results are intended as an interpretive and diagnostic contribution for precision gravitational experiments and related metrological systems, rather than as a proposal of new forces or new dynamical laws.