Quantum-Ready Intelligent Digital Systems for Open Finance: Integrating Post-Quantum Security and Evidence-Gated Quantum Computing

Open-finance services must prepare for cryptographic transitions while evaluating quantum-computing opportunities against classical alternatives. These decisions require different evidence but concern shared data, software, suppliers, and owners. This paper develops a design-science framework through a multivocal review of 60 sources. It links a system evidence graph, trust-transition register, quantum-experiment register, and capability-and-decision register across seven technical and organizational layers. The framework separates preparation priority from deployment feasibility, constrains maturity judgments by evidence, and gates experiments through authority, baseline quality, full-workflow accounting, and stopping rules. A hypothetical bank-account aggregation service illustrates discovery, a maturity cap, and an experiment stop decision. A change-event trace identifies the proposed integration beyond established migration records without claiming measured superiority. Two weight scenarios reverse the priority order of two work packages; criterion-removal and input sensitivity checks expose the dependence on exposure assumptions. The contribution is a specified linkage between migration, experimentation, and accountable review. No participants or operational deployment were assessed. The framework remains unvalidated; the example demonstrates inspectable decision mechanics, not security assurance or decision utility.