Structured Output
Also called: JSON mode, constrained decoding
Forcing the model to return data in a fixed schema so downstream code can parse it.
Structured output constrains generation to valid JSON or a supplied schema, rather than hoping a prompt produces parseable text. It is the difference between a demo and a pipeline, because it removes the whole class of ’the model added a friendly sentence before the JSON’ failures.
In practice: Guaranteeing every response has invoice_number, amount, and currency, or fails loudly.