Freshness as a First-Class Schema Concern: Modeling Data Staleness Across 83 Data Sources

I am not a developer, and I built a public reef atlas with AI agents . It pulls from 83 data sources that each update on their own schedule, some daily, some weekly, some once a decade. The hardest problem in the whole build was staleness, harder than the ocean science and harder than the frontend: how do you build a schema that tells the truth about how old each piece of data actually is, when the sources age so differently?