Harmony / chat template handling

Prompt

type ReasoningItem = {
  id: string;
  type: "reasoning";
  summary: SummaryContent[];
  // new
  content: ReasoningTextContent[];
};

type ReasoningTextContent = {
  type: "reasoning_text";
  text: string;
};

type ReasoningTextDeltaEvent = {
  type: "response.reasoning_text.delta";
  sequence_number: number;
  item_id: string;
  output_index: number;
  content_index: number;
  delta: string;
};

type ReasoningTextDoneEvent = {
  type: "response.reasoning_text.done";
  sequence_number: number;
  item_id: string;
  output_index: number;
  content_index: number;
  text: string;
};