useStreamLog.tsx

const startStream = useCallback(async (input: unknown, config: unknown) => {
    const controller = new AbortController();
    setController(controller);
    startRef.current?.({ input });

    let innerLatest: RunState | null = null;

    await fetchEventSource(resolveApiUrl("/stream_log").toString(), {
      signal: controller.signal,
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ input, config }),
      onmessage(msg) {
        if (msg.event === "data") {
          innerLatest = reducer(innerLatest, JSON.parse(msg.data)?.ops);
          setLatest(innerLatest);
          chunkRef.current?.(JSON.parse(msg.data), innerLatest);
        }
      },
      openWhenHidden: true,
      onclose() {
        setController(null);
        successRef.current?.({ input, output: innerLatest?.final_output });
      },
      onerror(error) {
        setController(null);
        errorRef.current?.(error);
        throw error;
      },
    });
  }, []);