Function startChatStream

frontend/src/api/ChatStreamAPI.ts:4–72

(
  input: ChatInputType,
  token: string,
  stream: boolean = false // Default to non-streaming for better performance
)

import authenticatedFetch from '@/lib/authenticatedFetch';

export interface ChatStreamHandlers {
  /** Assistant text as it arrives. */
  onText?: (delta: string) => void;
  /** A tool the agent just invoked, with what it is acting on when known. */
  onTool?: (name: string, target?: string) => void;
  /** Turn-level failure reported by the backend. */
  onError?: (message: string) => void;
}

export interface ChatStreamOptions extends ChatStreamHandlers {
  /** Aborts the request; the backend stops the agent when the client hangs up. */
  signal?: AbortSignal;
  /** Attached images as `data:<mime>;base64,<data>` URLs. */
  images?: string[];
}

/**
 * Runs one agent turn and returns the assembled assistant text.
 *
 * The backend streams newline-delimited JSON events rather than raw text, so
 * the caller can show which tool is running and which files changed while the
 * turn is still in flight.
 */
export const startChatStream = async (
  input: ChatInputType,
  token: string,
  { onText, onTool, onError, signal, images }: ChatStreamOptions = {}
): Promise<string> => {
  if (!token) {
    throw new Error('Not authenticated');
  }

  const { chatId, message, model } = input;
  const response = await authenticatedFetch('/api/chat', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: `Bearer ${token}`,
    },
    body: JSON.stringify({ chatId, message, model, images }),
    signal,
  });

  if (!response.ok) {
    throw new Error(
      `Network response was not ok: ${response.status} ${response.statusText}`
    );
  }

  const reader = response.body?.getReader();
  if (!reader) {
    throw new Error('No response body to read');
  }

  const decoder = new TextDecoder();
  let buffer = '';
  let content = '';