This article evaluates whether the post-2023 legal architecture for Indonesia's Nusantara Capital City (IKN) has converted green constitutional commitments into operational and reviewable environmental duties. It develops a Constitutional Green Compliance Framework (CGCF) from the constitutional right to a good and healthy environment, environmentally sustainable economic governance, and the earlier finding that IKN regulation remained vulnerable to a gap between constitutional aspiration and implementation. Using normative legal research, the study applies statutory, conceptual, and regulatory-design approaches to Law No. 3 of 2022 as amended by Law No. 21 of 2023, the IKN master-plan and spatial-planning instruments, Perka OIKN No. 8 of 2024, and Perka OIKN No. 17 of 2025. The audit examines six dimensions: constitutional traceability, ecological thresholds, decision controls, procedural rights, monitoring and disclosure, and remedial accountability. The analysis finds substantial regulatory consolidation, particularly through environmental planning, environmental approvals, recognition of local wisdom, information systems, supervision, and enforcement instruments. Nevertheless, compliance remains operationally partial because headline targets are not yet consistently linked to mandatory corrective triggers, publicly verifiable ecological budgets, independent review, and citizen-accessible remedies. Published evidence concerning biodiversity-sensitive urban growth, long-term water constraints, land-use conflict, and illegal mining reinforces the need for enforceable carrying-capacity limits. The article proposes a six-link CGCF that connects constitutional mandates to ecological budgets, decision gates, participatory assurance, public audit, and restoration-based remedies. Its contribution is to transform green constitutionalism from a justificatory principle into a repeatable compliance test for IKN governance.