Kinematic Coherence in the Milky Way Halo: A Data-Driven Framework with Gaia DR3 and Spectroscopic Surveys Radial Coherential Dynamics — Paper XXIV

We define a quantitative framework for testing kinematic coherence (Class IV) in the Milky Way stellar halo using Gaia DR3 cross-matched with spectroscopic surveys (APOGEE, LAMOST, SDSS). Three primary proxies are introduced: radial and tangential velocity correlation functions and the kinematic coherence length LKC. A two-layer null model combines the Jeans equation with simulation-calibrated correlation expectations (Illustris-TNG, FIRE, Auriga). An RCD-inspired structural alternative tests whether residual kinematic organization correlates with the quasi-static coherence profile C₀ (r) from Papers XIV-XVII. Four kill switches are defined. This paper (XXIV-a) specifies the framework; data-driven execution is deferred to XXIV-b.