templates/data-api-contract.md

# Data & API Contract

**User action / business invariant:**
**Entities, ownership and cardinalities:**
**Auth and tenancy boundaries:**
**Retention/deletion:**

| Operation | Access | Input | Output | Errors | Idempotency / retry |
| --- | --- | --- | --- | --- | --- |

**Schema evolution and migration:**
**Rate limits and observability:**