Opportunities or challenges? Upgrading of periphery space with the rise of platform urbanism: Live streaming commerce in Yangtze River Delta, China

The interplay between digital and physical space has been widely discussed with the rise of platform urbanism. The mechanisms by which digital platforms reshape the urban system, particularly peripheral ones within metropolitan regions, are not yet fully discussed. Building on the concept of platform urbanism, we integrate virtual-based urban positions and inter-city functions into the analysis of the live-streaming commerce (LSC) urban system. We combine both physical (spatial-based) and virtual (platform-based) dimensions, applying a dual core-periphery framework to categorize cities into four possible positions. Furthermore, we identify three typical modes of inter-city interaction named centripetal complementarity, reciprocal intermediation, and hierarchical bridging that capture the functional dynamics of metropolitan regions. Empirically, using unique LSC data from Alibaba and field interviews in the Yangtze River Delta, we move beyond position identification to show how peripheral cities engage in diverse interaction modes. We find that structural agglomeration, place-based policy, talent concentration, urban context, and geographical proximity jointly shape these linkages. Overall, we indicate that digital platforms reshape both the positional form and relational function of urban systems in metropolitan regions, offering new insights into peripheral upgrading and regional governance in the digital era.