Function streamChat

demo/chat/App.tsx:45–73

(
  messages: { role: string; content: string }[],
  onPart: (part: StreamPart) => void,
  signal: AbortSignal,
)

}

async function streamChat(
  messages: { role: string; content: string }[],
  onPart: (part: StreamPart) => void,
  signal: AbortSignal,
): Promise<void> {
  const res = await fetch("/api/chat", {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ messages }),
    signal,
  });

  if (!res.ok) {
    let detail = res.statusText;
    try {
      const json = (await res.json()) as { error?: string };
      detail = json.error ?? detail;
    } catch {
      detail = (await res.text()) || detail;
    }
    throw new Error(detail);
  }

  if (!res.body) {
    throw new Error("No response stream");
  }

  await readStreamParts(res.body, onPart, signal);
}

function newMessage(
  role: ChatMessage["role"],