> ## Documentation Index
> Fetch the complete documentation index at: https://docs.planasonix.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Data contracts

> Define and enforce data quality contracts between producers and consumers.

A **data contract** is a formal agreement between a data producer and downstream consumers: expected schema, nullability, value ranges, freshness SLAs, and ownership. In Planasonix, contracts attach to datasets or pipeline outputs and drive validation during CI, execution, or both.

## Contract creation

<Steps>
  <Step title="Choose the subject">
    Select a table, topic, or pipeline output stage the contract governs.
  </Step>

  <Step title="Define schema rules">
    Specify columns, types, keys, allowed enums, and null constraints. Import from Avro/JSON Schema/SQL DDL when supported to avoid transcription errors.
  </Step>

  <Step title="Add quality checks">
    Layer row-level rules (for example, `amount >= 0`, `country in ISO set`) beyond raw types.
  </Step>

  <Step title="Set severity">
    Decide whether violations fail the pipeline, quarantine rows, or only emit warnings to [diagnostics](/observability/diagnostics).
  </Step>

  <Step title="Publish">
    Version the contract; consumers pin to a version until they opt into upgrades.
  </Step>
</Steps>

## Schema validation

During runs, Planasonix compares incoming batches to the contract:

* **Additive** changes (new nullable columns) often pass automatically when policy allows.
* **Breaking** changes (type narrowing, dropped columns) fail fast or require a new contract version.

<Tabs>
  <Tab title="Producer-driven">
    Owning teams update contracts when they ship schema changes; CI blocks merges that skip contract bumps.
  </Tab>

  <Tab title="Consumer-driven">
    Critical dashboards declare required columns; producers receive failures when those columns disappear.
  </Tab>
</Tabs>

## Violation tracking

The **violations** view lists timestamps, rule names, sample offending rows (redacted per policy), and pipeline runs. Export violations for incident tickets or compliance evidence.

## Enforcement

Enforcement hooks include:

* Failing the pipeline before writes commit
* Writing bad rows to a quarantine table or [dead letter queue](/observability/dead-letter-queue)
* Emitting alerts to [Notifications](/settings/notifications) channels

<Warning>
  Quarantine tables may contain sensitive values. Apply retention, encryption, and access controls identical to production data classes.
</Warning>

## Related topics

<CardGroup cols={2}>
  <Card title="Data catalog" icon="books" href="/governance/data-catalog">
    Document datasets contracts protect.
  </Card>

  <Card title="Impact analysis" icon="chart-network" href="/governance/impact-analysis">
    See who breaks when contracts change.
  </Card>
</CardGroup>