Delocalisation, not decentralisation: a small fraction of non-local ledger links shifts construction supply networks into a mean-field coordination transition

Distributed-ledger technologies are expected to improve coordination in construction supply networks, yet realised benefits are uneven. We model ledger-mediated verification as a collective coordination problem on networks and examine how network structure affects the transition from hub-mediated to peer-mediated verification. Using a statistical-mechanics model with a single normalised control parameter and no empirically fitted parameters, we simulate spatially embedded and non-spatial verification networks with cluster Monte Carlo methods. The numerical approach is first validated against established benchmark results. The model exhibits a continuous coordination transition, but its behaviour depends strongly on network topology. Purely local verification networks display non-mean-field behaviour and require a higher critical threshold than non-spatial networks. Rewiring only 5% of links to distant counterparties shifts the system close to mean-field behaviour and substantially lowers the threshold, with little further change at higher rewiring levels. The results suggest that the key structural effect of a distributed ledger is not simply decentralisation, but delocalisation: enabling verification across otherwise local boundaries. Even a small proportion of long-range verification links can therefore alter collective coordination dynamics and reduce the connectivity required for system-wide change.