# Build and run evals

Validation proves an ontology can be imported. Evals prove a change still answers important business questions correctly.

## Add a trusted case

Start with a real question whose correct behavior matters. Fix the ontology, then propose the question and its expected SQL together with the business assumptions that SQL encodes.

Have a domain owner or designated reviewer validate both the interpretation and the SQL before adding the case. SQL that runs is not necessarily SQL that expresses the right business rule.

## How cases are judged

- **Warehouse-connected** Cassis executes the generated and expected SQL, then compares their result rows deterministically, with tolerance for insignificant numeric differences.

- **Schema-only** Neither query can run. An LLM equivalence judge compares the SQL logic and explains whether it matches.

## Run before merge

- **In the web app** Run the suite against the published ontology or an app branch.

- **From a checkout** `cassis eval run` tests the local ontology without publishing it.

- **In CI** Run the same command on pull requests so regressions block the merge.

Failures return to the [Review queue](/curate/issues/) with their evidence attached.

Remove or update a case when the approved business definition changes. A stale expected query makes the suite noisy and easier to ignore.

Command syntax lives in the [eval reference](/reference/cli/eval/).