RCD 2.0 — Paper P1 v1.1: Minimal Candidate for S_eff[C] — Parent Action with Sectorial Reductions and Hamming–Continuum Bridge

We construct the minimal parent effective action S_eff[C] = S_loc[C] + S_conf[C] for the coherential field C(x,t) of the RCD 2.0 program. The local block S_loc reproduces the established cosmological P2 sector in the homogeneous/infrared regime. The configuration block S_conf introduces a bilocal coupling through a saturating kernel that induces a coarse-grained configuration dissimilarity functional D_K[C_1, C_2] with finite resolution C_*. Under lattice regularization with binary field truncation and local kernel, D_K reduces to a quantity proportional to the Hamming distance d_H, providing the formal structural bridge between the GHZ empirical anchor (P0-a) and the parent coherential action. The integro-differential equation of motion, the formal nonlocal stress-energy tensor, and a covariant gradient expansion in Riemann normal coordinates are derived. Linear stability is established for positive instantaneous kernels. The structural bridge (D_K → d_H) is distinguished from the dynamical bridge (ρ ∝ exp(−Γ D_K)), which remains an explicit conjecture. Part of the RCD 2.0 program (Radial Coherential Dynamics).