OutputFormat

The response format of an agent's answer (design 4.26): the JSON schema its final answer must match, and the type it must read as. A model call of the agent that offers no tools carries the schema as its responseFormat (see ModelStep.fromClient), the system prompt always states it, and an answer is checked inside the model step: an invalid one is retried once, and a second ends the turn with org.llm4s.agent.graph.GraphError.OutputInvalid. Build one with OutputFormat.of; AgentBuilder.withOutput does.