Assess and compare the effectiveness and socio-ecological trade-offs of managed retreat versus engineered coastal defenses for long-term coastal resilience under multiple sea-level rise (SLR) scenarios. Test ability to evaluate risk reduction, lifecycle costs, ecosystem services and biodiversity impacts, social equity and cultural heritage consequences, governance and implementation barriers, and adaptive capacity across low/medium/high SLR pathways and time horizons; require interpretation of modeling or case-study evidence, trade-off analysis (including cost–benefit and stakeholder considerations), and clear, evidence-based policy recommendations under uncertainty.