RCD 2.0 designates the recentering, governance, and multiscale-closure phase of the Radial Coherential Dynamics (RCD) program. This document, Paper 0, serves as its constitutional framework. It does not introduce new phenomenology; instead, it fixes the formal architecture of the program, classifies the full corpus by epistemic status, and converts the next stage of development into an executable mathematical roadmap. The document has three functions. First, it states the unifying principle of RCD: a coherential field C(x,t) whose dynamics underlie the program's cosmological, galactic, gravitational, and quantum sectors. Second, it establishes a governance taxonomy with four operational levels — derived core, motivational-confirmatory core, phenomenological satellite, and programmatic infrastructure — together with a full corpus matrix and explicit kill switches for reclassification. Third, it defines the roadmap P0–P7, whose central tasks are: closing the formal bridge between the GHZ quantum experiments and the coherential action, specifying a unified effective action S_eff[C], constructing explicit multiscale matching rules between quantum, galactic, and cosmological regimes, and replacing phenomenological kernels or completions by derivations from the core dynamics. Within this framework, the GHZ block is fixed as the empirical anchor of the program and as the first experimentally accredited sectorial prediction of RCD. Paper 0 therefore functions as the constitution, governance charter, and execution map of RCD 2.0.