Nonequilibrium Action, Detailed-Balance Obstruction, and a T-Odd Medium Functional in the Allen–Cahn/Wright–Fisher RCD Kernel

This upload presents version 0.1 of RCD-NB-01, a Nivel B technical preprint within the Radial Coherential Dynamics (RCD) program. The work characterizes the nonequilibrium thermodynamic structure of the validated Regime III Allen–Cahn/Wright–Fisher coherence-field kernel. The paper constructs the Itô MSR-Janssen-De Dominicis effective action of the kernel, establishes a detailed-balance obstruction from mobility mismatch, derives interfacial localization of the active fluctuating sector, validates the T-odd / medium-functional estimator with additive and multiplicative analytic arbiters, and measures the medium functional on a bit-equivalent 2D radiation coarsening trajectory with a three-seed audit. The result is deliberately stated at Nivel B: an effective, falsifiable thermodynamic characterization of an already validated stochastic process. It does not derive a parent action, does not claim emergent geometry, and does not close the field-level total entropy production. The Fokker–Planck current attempt is included as PARTIAL / inconclusive and is not presented as evidence of positive total entropy production. The upload includes the paper PDF and Markdown source, scripts, data, result logs, protocol files, README, citation metadata, and licensing files. Paper, data, and logs are licensed CC-BY 4.0; code/scripts are licensed MIT as indicated in LICENSE-CODE.