- invariant.spec: a turn/end whose step does not match the last opened step fails with 'expected last step'. - session.spec: a seed message whose content is not an array fails with 'message has invalid content'.
- invariant.spec: a turn/end whose step does not match the last opened step fails with 'expected last step'. - session.spec: a seed message whose content is not an array fails with 'message has invalid content'.