Schema introspection

Three tools cover dataset discovery:

• list_dataverses(cluster) — every dataverse in metadata
• list_datasets(dataverse, cluster) — datasets, optionally scoped
• infer_schema(dataset, sample_size, cluster) — sample N docs, summarise observed top-level fields

Inferring a useful schema

infer_schema reads up to sample_size documents (default 100) and returns: