Rapid urbanisation across the Global South has intensified contestation over sidewalk space, where formal planning collides with informal livelihoods. Street vending, central to the urban economy, is routinely framed as disorder and met with exclusionary interventions that overlook its socio-spatial logic. This paper asks who holds the right to the sidewalk in intermediary cities, and how planning can move from displacement toward negotiated coexistence. Using Ben Guerir, Morocco, as a case, the study integrates Space Syntax (global integration Rn, ArcGIS Pro), 60 h of behavioural mapping across 18 sessions recording 158 vendors in three daily time-bands, and a stratified perception survey (n = 120: 60 pedestrians, 30 vendors, 30 shopkeepers). Vending concentrates in the most integrated segments of the urban grid, follows pedestrian rhythms across the day, and persists despite the formal Souk Al Karama market, which remains underutilised due to its spatial isolation. The contribution is threefold: (i) extending Space Syntax and Right to the City scholarship to an under-studied intermediary-city context; (ii) showing empirically that informal vending is a spatially rational adaptation to urban accessibility, not encroachment; and (iii) translating findings into operational principles for inclusive sidewalk governance, advancing Sustainable Development Goals 8 and 11.