Kinematic Decoupling and Negative Velocity Divergence: An Observational Protocol for Type III Macro-Engineering Technosignature

The search for Type III macro-engineering technosignatures has historically lacked rigorous observational metrics capable of distinguishing artificial stellar propulsion from natural gravitational dynamics. We present a novel theoretical framework utilizing a Thermodynamic Extraction Depth ($D_T$) bound and a kinematic divergence metric ($M_{CME}$) designed to identify active mass clustering. By employing the Weak Equivalence Principle to isolate the kinematic decoupling of stars from the local interstellar medium (ISM), we establish a filter against dark matter sub-halos. As a proof-of-concept, we deployed a k-nearest neighbors divergence tensor algorithm on 6D phase-space data from the ESA Gaia DR3 archive, targeting a 1.0-degree radius in the Pleiades sector. The pipeline successfully flagged a highly anomalous, non-virialized sub-population of 17 stars ($\nabla \cdot \vec{v} \ll 0$). Profiling the most extreme candidates revealed a chaotic velocity dispersion and significant metallicity scatter, including a high-velocity, metal-poor interloper ($-109.15$ km/s, $[\text{Fe/H}] \approx -0.69$). Subsequent cross-matching with HI4PI and AllWISE catalogs revealed severe kinematic decoupling ($\Delta v > 116$ km/s) and a massive mid-infrared excess ($W3-W4 = 3.37$). While alternative natural hypotheses must be constrained, this pipeline successfully demonstrates the capability to detect chemically diverse, non-gravitational kinematic convergence and photometric anomalies in large-scale astrometric datasets.