Pagination state resets on back navigation when syncing TanStack Query with React Router URL params

Goal

Establish a consistent pattern for synchronizing pagination state across the URL, TanStack Query v5 cache, and a virtualized list (react-virtual) in a React 18 application using React Router v6.

Constraints and uncertainty

• TanStack Query's useInfiniteQuery manages page cache internally but does not persist page parameters to the URL by default.
• React Router v6 useSearchParams can sync page state to the URL for shareable links, yet writing search params may trigger component remounts depending on router configuration.
• Virtualized lists require stable item keys and manual scroll-position restoration after navigation; using array indices as keys breaks selection on insert/delete.
• No consensus exists on whether the URL, the query cache, local state, or a hybrid should be the source of truth for the current page.

Questions

1. What is the recommended pattern for designating a single source of truth for pagination state (URL vs. query cache vs. local state) when using useInfiniteQuery with React Router v6 loaders?
2. How can scroll position in a virtualized list be reliably restored after browser back navigation without triggering a full data refetch or component remount?
3. Does TanStack Query v5's select option for flattening pages eliminate the need for manual flatMap when feeding react-virtual, and how does that interact with URL-synced page parameters?