Community engagement is to cities what user experience is to computing: it signifies a large category that simultaneously speaks to general qualities of interaction and to specific ways of doing that interaction. Recently, digital civics has emerged as a research area with a comprehensive approach to designing for civic encounters where community engagement is a primary concern for designing systems and processes that support broad civic interaction. In short, over the past year, we worked with municipal officials, service providers, and city residents to design a community engagement playbook detailing best practices for city-scale engagement. The playbook, as well as the collaborative process that produced it, provides a roadmap for thinking through the kinds of systems that might populate the design space of city-scale digital civics. This paper details our design-led research process and builds on emerging literature on designing for digital civic interaction.