Data contract

A data contract is an explicit agreement between whoever produces a dataset or event and whoever consumes it, covering field names, types, meaning, freshness and what counts as a breaking change. Lifecycle teams need them because a silent rename in a checkout event kills a triggered campaign without raising an error anywhere. To work, the contract has to be enforced in the producer's own pipeline, tested automatically and able to block a release. Otherwise it is documentation that everyone quietly drifts from.