A guided walk through the matryoshka for Barcelona. Community. City. Region. Stop. Then look up at the boundary.
The narrated version of the aggregation atlas: the matryoshka — Community nested inside City nested inside Region — read step by step, for anyone meeting the index without slides. Each step shows the data the actor at that scale logs in a typical month, the cadence at which it lands, and the handoff sentence to the next ring. A status pill on each step marks its data as partial (some real Barcelona feeds) or mock (sample values). Step 3 is the governance ceiling — the matryoshka aggregation ends there. Below the ceiling rule, steps 4 and 5 render in the boundary register: italic, lower density, framed as observation not aggregation.
The walk is one minute and a half. It is the explanation a mayor, a lab lead, or an external reviewer can be talked through without slides. It is also the test of whether the matryoshka stop at Region is conceptually defensible: by the time the ceiling rule appears, the reader should already know why the next two scales are boundary observations and not aggregations. If they do not — the page has failed.
↪ Return to the aggregation atlas · drill into the embedding prefix relationship · or examine the per-pillar transition rules.