data-contractlisted

# Data Contract The producer commits to a shape and a schedule. Consumers build against it. Breaking it without notice is an outage, not a refactor. ## Template ```yaml name: <dataset or event name> owner: <team, plus a named person> description: <what it represents in business terms> schema: - name: <field> type: <type> nullable: <bool> classification: public | internal | confidential | pii description: <semantics, units, allowed values> semantics: grain: <one row per WHAT — answer this first> primary_key: [<fields>] late_arrival: <how late records are handled, and the cutoff> timezone: <explicit. Never "local".> sla: freshness: <max lag, and what consumers should do when breached> availability: <target> completeness: <expected row count range> quality_checks: [<the checks that gate publication>] versioning: policy: additive-only | versioned endpoints deprecation_notice: <period> ``` ## Worked example Two versions of one field: **Ambiguous — three consumers will interpret it three ways:** ```yaml - name: amount type: decimal description: The order amount ``` *Which* amount? Gross or net? Tax included? Which currency? Refunds negative or a separate row? Each consumer picks an answer, and the three dashboards disagree forever. **Unambiguous:** ```yaml - name: amount_net_minor type: integer nullable: false classification: internal description: > Order value excluding tax and shipping, after discounts, in the min