Synthetic population system
Population changes without losing the people in the math.
Synthetic aggregate cohorts conserve population across migration and aging, account explicitly for births and deaths, and support the fictional households now visible in Harbor Point.
Conservation ledger
Every event batch proves that ending population equals starting population plus births minus deaths. Transfers cannot create or erase residents.
Aggregate by default
Large populations stay in uncertainty-labeled cohorts. Named residents remain explicitly fictional and bounded to the playable city.
v1 boundary
No real demographic source, private person, identity reconstruction, live population feed, database, or AI provider is active.