QueryClient, Provider and Important Defaults Install v5.103.1 and build a predictable cache boundary
Phase 22 - TanStack Query Volume 06 - Professional Frontend
Install the two Phase 22 packages cd apps/web pnpm add @tanstack/react-query@5.103.1 pnpm add -D @tanstack/react-query-devtools@5.103.1
Create one stable browser QueryClient The provider is a Client Component because QueryClientProvider uses React context. The rest of the App Router tree does not become client-only merely because it is passed through this provider.
// apps/web/src/lib/query/get-query-client.ts import { environmentManager, QueryClient } from "@tanstack/react-query";
function makeQueryClient() { return new QueryClient({ defaultOptions: { queries: { staleTime: 30_000, retry: 2, }, mutations: { retry: 0 }, }, }); }
let browserQueryClient: QueryClient | undefined;export function getQueryClient() { if (environmentManager.isServer()) return makeQueryClient(); if (!browserQueryClient) browserQueryClient = makeQueryClient(); return browserQueryClient; }
// apps/web/src/app/providers.tsx "use client";
import { QueryClientProvider } from "@tanstack/react-query";
import { ReactQueryDevtools } from "@tanstack/react-query-devtools";
import { getQueryClient } from "@/lib/query/get-query-client";export function Providers({ children }: { children: React.ReactNode }) {
const queryClient = getQueryClient();
return (
<QueryClientProvider client={queryClient}>
{children}
<ReactQueryDevtools initialIsOpen={false} />
</QueryClientProvider>
);
}staleTime controls when data is considered fresh. gcTime controls how long inactive query data remains before garbage collection. They answer different questions. TaskFlow starts with a modest 30-second freshness window, then overrides it where the domain requires different behavior.
Cached query data is stale by default unless staleTime is configured. Inactive queries are garbage-collected after five minutes by default. Client queries retry failures three times by default, but TaskFlow deliberately starts with a smaller retry budget.
A default is a policy decision Do not copy staleTime values from another application. A stock-price dashboard, an HR directory and a static country list have different freshness expectations. Global defaults are baselines; individual queries can override them when the domain requires it.
staleTime 30 seconds Avoid immediate duplicate refetch after hydration while keeping Tasks reasonably fresh
gcTime library default No evidence yet that TaskFlow needs a different inactive-cache lifetime
query retry up to 2 selected transient failures Avoid long retry loops while tolerating brief transport faults
mutation retry 0 Writes should not repeat automatically unless idempotency is designed
TanStack Query is a server-state synchronization system, not merely a fetch helper. Cache identity, freshness, invalidation, and mutation semantics are the core model.
Restate the goal of “QueryClient Provider and Important Defaults” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: component → query key → cache state → fetch/mutation → reconciliation. Mark the one boundary this lesson changes.
Inspect the current repository state and record the exact files, route, table, or runtime involved. Avoid creating an abstraction before you can name the existing owner.
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
Connect the slice to TaskFlow’s phase artifact: TaskFlow query/mutation layer with stable keys, list/detail caching, invalidation, filters, and debugging via devtools/logs.. Verify behavior from the outside as a user or API client would.
Create one controlled failure that is safe to reproduce. Predict the symptom first, capture evidence, locate the earliest broken boundary, then fix only that cause.
Close the reference and rebuild or explain the core change from memory. Record what you would monitor or test before trusting the same change in production.
export const taskKeys = {
all: ["tasks"] as const,
list: (filters: TaskFilters) => ["tasks", "list", filters] as const,
detail: (id: string) => ["tasks", "detail", id] as const,
};Do not copy this as a finished answer. Predict what each boundary does, type the smallest useful slice, run it, then compare the result with your prediction.
Return to the nearest observable boundary: input, network, process log, database, or rendered UI. Compare actual evidence with the predicted path.
Change one variable at a time and reproduce the original failure after the fix; otherwise you have correlation, not diagnosis.
Without copying the final source, create a second small scenario that applies “QueryClient Provider and Important Defaults” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Define a query-key factory that includes every parameter affecting the result.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Copying query data into useState/useEffect
Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.Why does this responsibility live here, what input does it trust, what output proves success, and what would go wrong if another layer owned it?
If your explanation is vague, repeat the boundary trace before moving on.Close the reference. Reproduce the core idea from memory or explain the exact request/data flow aloud. Then check your diff or notes for accidental shortcuts that bypass validation, authorization, error handling, or verification earned in earlier phases.