JSON types on this card.

A value in quotes is a string.
A value in braces is an object.
An object can be well-formed JSON and still violate a schema that requires a string.

worked username ada: string. Meets the schema.
activity username lane: string. Meets the schema.
activity username object with kind: object. Does not meet the schema.

This card does not use a database product's operator names.
The server rejects the object because the type is wrong.
A check that runs only in the browser is not this decision.