If a team in one city runs an experiment and shares it—say at bimonthly hackathons—others can reuse parts elsewhere. An air‑quality visualization network (AirBox) solved “no one trusts the other sector’s measurements.” The same stack can visualize water quality, manage river pollution, or support local referenda. When mask availability became the problem, the same stack was repurposed overnight for mask maps and routing, with OpenStreetMap folks. The “three‑day mask map miracle” happened not because we had GPT‑5 back then, but because the infrastructure from air and water maps already existed.