Function sendMessageStream

ui/node-react/client/src/api.js:82–153

(chatId, query, history, docs, datasets, messageOffset, callbacks)

 * Returns a promise that resolves when streaming is complete.
 */
export async function sendMessageStream(chatId, query, history, docs, datasets, messageOffset, callbacks) {
  const { onStep, onToken, onDocuments, onDone, onError } = callbacks;

  const res = await fetch(`${API_BASE}/chats/${chatId}/message/stream`, {
    method: 'POST',
    headers: getHeaders(),
    body: JSON.stringify({ query, history, docs, datasets, messageOffset }),
  });

  if (!res.ok) {
    const errText = await res.text();
    throw new Error(errText || 'Chat stream failed');
  }

  const reader = res.body.getReader();
  const decoder = new TextDecoder();
  let buffer = '';

  while (true) {
    const { done, value } = await reader.read();
    if (done) break;

    buffer += decoder.decode(value, { stream: true });

    // Process complete SSE messages (separated by double newline)
    let boundary = buffer.indexOf('\n\n');
    while (boundary !== -1) {
      const message = buffer.substring(0, boundary);
      buffer = buffer.substring(boundary + 2);

      // Parse the SSE message
      let eventType = 'message';
      let dataStr = '';
      for (const line of message.split('\n')) {
        if (line.startsWith('event: ')) {
          eventType = line.substring(7).trim();
        } else if (line.startsWith('data: ')) {
          dataStr += line.substring(6);
        }
      }

      if (dataStr) {
        try {
          const parsed = JSON.parse(dataStr);
          switch (eventType) {
            case 'step':
              onStep?.(parsed.step);
              break;
            case 'token':
              onToken?.(parsed.token);
              break;
            case 'documents':
              onDocuments?.(parsed.documents);
              break;
            case 'done':
              onDone?.(parsed);
              break;
            case 'error':