StoreData
data class StoreData<out T>(val data: T?, val error: Throwable? = null, val fetchedAt: Instant? = null, val isRefreshing: Boolean = false)
A snapshot from the caller's data pipeline: the latest data (or null), the last error, when it was last successfully fetched (fetchedAt), and whether a refresh is in flight. Deliberately not tied to any store library — a repository fills this in however it likes.