This work proposes a novel framework to reconstruct economically optimal flow-based domains, consistent with the physical constraints of the European transmission network. Building on a hybrid zonal–nodal market optimization model, we jointly represent day-ahead market clearing and nodal security-constrained redispatch, enabling the explicit evaluation of total social economic welfare. By exploiting the Karush–Kuhn–Tucker optimality conditions of the classical day-ahead flow-based market coupling problem, we derive calibrated parameters that ensure consistency between zonal market outcomes and underlying nodal physics. Numerical experiments on a benchmark system show that the method systematically reconstructs tightened or enlarged flow based domains—depending on forecast conditions—without compromising network security, while improving social economic welfare and reducing redispatch costs. The approach opens the way toward scalable applications on large European networks and uncertainty-aware stochastic extensions.