From Marginality to Resilience: Sustainable Architecture and Economic Diplomacy in the Sari-Su Border Market at the Iran–Türkiye Border

Peripheral border markets are often marked by institutional fragmentation, spatial underdevelopment, and digital disconnection, although in some regions they operate as highly integrated economic corridors. Despite their geopolitical importance, these markets remain underexplored in frameworks that integrate spatial planning, digital trade, and economic diplomacy. This study introduces the Spatial – Economic Sustainability (SES) framework, a triadic model linking sustainable architecture, digital trade systems, and cross-border institutional coordination. Central to the framework are three analytical tools: the Border Market Sustainability Index (BMSI) to quantify sustainability, the Diplomatic – Infrastructure Parity Index (DIPI) to highlight policy capacity gaps, and agent-based modeling (ABM) to simulate intervention outcomes. The SES model was applied to the Sari-Su border market in Maku, West Azerbaijan Province, Iran, near the Türkiye border – an area characterized by informal trade dependency, institutional volatility, and limited infrastructural capacity. Using a mixed-methods design that combined Delphi panels with AHP – TOPSIS prioritization and ABM simulations, the study shows that integrated reforms could reduce informal trade by 18%, double institutional resilience, and enhance cross-border policy coherence. Overall, the findings confirm that spatial – digital – diplomatic integration strengthens sustainability in fragile border zones, offering a transferable planning tool for similar markets across Asia, Africa, and Latin America.