Projects to integrate digital technologies into the fabric of city life depend upon specific visions of politics and technology. In the process of their realization, they re-constitute the identities, agencies, and relations of human inhabitants, re-defining what it means to be a citizen. This article draws on the idiom of co-production and framework of constitutionalism from Science and Technology Studies (STS) to analyze the coming into being of a form of citizenship with smartphone technologies in Boston in the 2010s. When the Boston Mayor’s Office of New Urban Mechanics (MONUM) used newly available smartphone apps to reconfigure the connection among city residents and government, they brought into being a specific mode of citizenship. I term this mode of citizenship “mechanic” to draw attention to the qualities of passivity, infrastructure, and connectedness that characterized MONUM’s early digital citizenship projects. I argue that recognizing that the constitution of the human, and specifically of citizens, is at stake in smart city projects entails re-thinking ethical analysis in contexts of smart cities. Instead of seeking to perform ethical assessments of technological consequences (“ethics of” approach), scholars might begin with a situated analysis of how humans as citizens are constituted through smart city projects (“ethics in” approach). By identifying the political affordances and commitments of the emergent digital citizenship models, scholars can make visible alternative forms of living and engaging politically in the city.