ADR 0004: Bronze, Silver, and Gold

Context

Auditable ingestion must survive source changes and reproduce canonical data offline.

Decision

Persist immutable checksummed Bronze, validated canonical Silver, and deterministic curated Gold.

Alternatives

Persisting only final frames or naming identical copies as layers were considered.

Consequences

Storage cost increases, while replay, lineage, schema diagnosis, and reproducibility improve.

Rejected shortcuts

Raw-data loss, secret-bearing metadata, and network-dependent Gold calculations are rejected.

Operational implications

Retention and filesystem access must be configured; replay verifies checksums before parsing.