Variable FeedTimelineCursorSchema`Const`

FeedTimelineCursorSchema: Struct<
    {
        lastTakenAt: optionalKey<Number>;
        nextMaxId: optionalKey<String>;
        position: optionalKey<Number>;
        reason: Enum<typeof TimelineFeedReason>;
        requestId: optionalKey<String>;
    },
> = ...

The cursor as a checkpoint stores it: the page-after cursor the feed's next request is made with. A checkpoint decodes the stored value through it before any page is requested with it.