GTFS
GTFS (General Transit Feed Specification) is the open format transit agencies use to publish their schedules: a set of linked CSV tables (agencies, routes, trips, stops, stop times, calendars) joined by keys. A trip belongs to a route, a stop time belongs to a trip and a stop. That makes a feed a natural dependency graph, and a good test for an engine that recomputes only what a change touches.
Each dataset below is loaded into .me as paths, with derived values (counts, totals) defined over the key relations. Then real update archives are replayed as writes, and every write records how many derived values it recomputed (k) and how long it took.
