The State λ Paradox: Programmable Friction, Welfare Targeting, and the Case for Dual-Track CBDC Design

This paper develops a theoretical and behavioural framework for analysing programmable Central Bank Digital Currency (CBDC) systems and welfare-targeted monetary design. The study introduces the “Digital Envelope Model” and the programmable friction parameter (λ) to examine the trade-off between welfare targeting efficiency and consumer autonomy. Combining behavioural economics, monetary policy, and digital finance, the paper proposes a Dual-Track CBDC framework designed to balance programmability with monetary flexibility. The study integrates theoretical analysis with empirical survey evidence from bilingual households in Varanasi, India.