Core Flow is the data platform behind Dutch nature monitoring, designed around one question: what will someone be able to read in fifty years, with no account, no licence, and no us? Everything is stored as open files (Parquet) on S3-compatible object storage and queried directly with DuckDB, so there is no database to outlive and no proprietary layer to replace. Each dataset carries a stable UUID identity, so names and paths can change without breaking references, and data is append-only and historized, so you can ask what was known on any past date. There are no standing servers: scheduled jobs run on the GitLab CI runners we already have. The talk walks through the principles (no vendor lock-in, sovereignty, durability and cost) and how each one shaped the architecture.