Function createBatchedMessageUpdater

cli/src/utils/message-updater.ts:124–279

(
  aiMessageId: string,
  setMessages: SetMessagesFn,
  flushIntervalMs: number = DEFAULT_FLUSH_INTERVAL_MS,
)

/** Batched updater that queues updates and flushes at a regular interval. */
export const createBatchedMessageUpdater = (
  aiMessageId: string,
  setMessages: SetMessagesFn,
  flushIntervalMs: number = DEFAULT_FLUSH_INTERVAL_MS,
): BatchedMessageUpdater => {
  // Queue of message updater functions to be applied on next flush
  const pendingUpdaters: Array<(msg: ChatMessage) => ChatMessage> = []
  let intervalId: ReturnType<typeof setInterval> | null = null
  let isDisposed = false

  const flush = () => {
    if (pendingUpdaters.length === 0) return

    // Capture and clear the queue atomically
    const updaters = pendingUpdaters.splice(0, pendingUpdaters.length)

    // Compose all pending updaters into a single transform
    const composedUpdater = (msg: ChatMessage): ChatMessage => {
      return updaters.reduce((m, fn) => fn(m), msg)
    }

    // Apply composed update to the target message
    setMessages((prev) =>
      prev.map((msg) => (msg.id === aiMessageId ? composedUpdater(msg) : msg)),
    )
  }

  const dispose = () => {
    if (isDisposed) return
    // Flush any pending updates before disposing to prevent data loss
    flush()
    isDisposed = true
    if (intervalId !== null) {
      clearInterval(intervalId)
      intervalId = null
    }
  }

  // Start the periodic flush interval
  intervalId = setInterval(flush, flushIntervalMs)

  const updateAiMessage = (updater: (msg: ChatMessage) => ChatMessage) => {
    if (isDisposed) {
      // If disposed, apply immediately as fallback
      setMessages((prev) =>
        prev.map((msg) => (msg.id === aiMessageId ? updater(msg) : msg)),
      )
      return
    }
    pendingUpdaters.push(updater)
  }

  const updateAiMessageBlocks = (
    blockUpdater: (blocks: ContentBlock[]) => ContentBlock[],
  ) => {
    updateAiMessage((msg) => ({
      ...msg,
      blocks: blockUpdater(msg.blocks ?? []),