Tanstack Query

TanStack Query

Use this skill when work touches TanStack Query v5, especially @tanstack/react-query, server-state caching, query/mutation lifecycle issues, SSR hydration, or migrations from React Query/TanStack Query v4.

Workflow

1. Inspect the local Query shape before changing code:
   • Package versions for @tanstack/react-query, @tanstack/query-core, devtools, persist/broadcast packages, ESLint plugin, React, framework router, and test utilities.
   • Provider setup: QueryClient, QueryClientProvider, SSR request scoping, default options, devtools, and persistence providers.
   • Query conventions: query key factories, queryOptions, mutationOptions, custom hooks, router loaders, SSR prefetching, and invalidation helpers.
   • Runtime intent: client-only fetching, server prefetch and hydration, route preloading, offline/persistence, or multi-tab sync.
2. Refresh docs for current behavior, package drift, SSR, persistence, or migrations. Start from source-map.md.
3. For installation, provider setup, defaults, query keys, useQuery, and TypeScript options, use setup-core.md.
4. For dependent, parallel, paginated, infinite, disabled, cancellable, selected, and performance-sensitive queries, use query-patterns.md.
5. For useMutation, invalidation, direct cache writes, optimistic updates, mutation scopes, and offline mutations, use mutations-cache.md.
6. For prefetching, router integration, SSR, hydration, Suspense, Server Components, and streaming caveats, use ssr-prefetching.md.
7. For persistence, broadcast sync, devtools, ESLint, testing, and migration checks, use production-tooling.md.

Implementation Judgment

• Treat TanStack Query as server-state management, not a replacement for local client UI state.
• Query keys are cache identity. Include every changing variable used by the query function, and keep keys serializable.
• Prefer object syntax everywhere in v5. Do not reintroduce positional v3/v4 signatures.
• Prefer typed queryOptions and mutationOptions helpers for reusable queries and mutations.
• Set staleTime deliberately. Default stale data refetches on mount, window focus, and reconnect can be correct, but noisy when misunderstood.
• Use targeted invalidation as the default after mutations. Use immutable setQueryData when the mutation response already contains the exact updated object.
• For optimistic updates, prefer UI-level variables when only one surface needs the pending state; use cache-level onMutate rollback when multiple surfaces must react.
• In SSR, create request-scoped query clients on the server and a stable browser client. Avoid module-level server caches that leak data across users.
• In tests, isolate each test with its own QueryClient, turn retries off, and clear or recreate clients rather than sharing cache state.

Verification

Prefer the repo's existing checks. For meaningful TanStack Query changes, include the relevant subset:

• Typecheck for query keys, query function returns, select, mutation variables, and SSR hydration types.
• Focused tests for invalidation, optimistic rollback, cache updates, dependent queries, pagination, infinite queries, and error states.
• Browser smoke for loading, stale-data, background-fetching, pagination, mutation pending/error, hydration, and focus/reconnect behavior.
• SSR or route-loader smoke when changing prefetching, hydration, stale times, or provider placement.
• ESLint Query plugin checks when the repo uses @tanstack/eslint-plugin-query.