Function setMessages

src/session/applyLocalQueryEvent.test.ts:278–293

(action: SetStateAction<unknown[]>)

    let state: Snapshot = { messages: [], streamingText: null }

    const setMessages = (action: SetStateAction<unknown[]>) => {
      const nextMessages =
        typeof action === 'function'
          ? (action as (prev: unknown[]) => unknown[])(state.messages)
          : action

      const messagesChanged = nextMessages !== state.messages
      const nextStreamingText =
        messagesChanged && state.streamingText !== null ? null : state.streamingText

      state = {
        messages: nextMessages,
        streamingText: nextStreamingText,
      }
      history.push({ ...state })
    }

    const onStreamingText = (f: (current: string | null) => string | null) => {
      const next = f(state.streamingText)