Data Contract Enforcer

When to invoke

• "Run the data contract for fct_orders before merge."
• "Check the contracts of all models in CI."
• "Validate freshness on dim_users."

Inputs needed

1. Contract YAML — describes expected schema, freshness, and constraints.
2. Connection — Snowflake / BigQuery / DuckDB / Postgres (DuckDB used for examples).

Workflow

1. Load the contract.
2. Inspect the live table.
3. Diff schema (columns + types + nullability).
4. Run assertions: freshness, row-count bounds, uniqueness, allowed values.
5. Report — Markdown + JSON; exit code 0 (pass) or 1 (violations).