What is tanstack-query?

A set of rules for using TanStack Query v5, a library that fetches and caches data from servers in client-side applications. It defines how queries, mutations, validation, cache keys, and the shared query client should be organized.

Use it when adding or changing server-data fetching in a React single-page app, including query definitions, mutations, cache updates, and development tools.

It prevents duplicated fetching logic, inconsistent cache behavior, unsafe response handling, and multiple query clients being created by mistake.

tanstack-query — Cursor rule for Cursor by louisbrulenaudet: A set of rules for using TanStack Query v5…

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add rules/louisbrulenaudet/monorepo-template/tanstack-query

Clone the repo

git clone --depth 1 https://github.com/louisbrulenaudet/monorepo-template

Made for: Cursor.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/rules/louisbrulenaudet/monorepo-template/tanstack-query.svg)](https://agentmods.dev/rules/louisbrulenaudet/monorepo-template/tanstack-query)

Your own site

<a href="https://agentmods.dev/rules/louisbrulenaudet/monorepo-template/tanstack-query"><img src="https://agentmods.dev/badge/rules/louisbrulenaudet/monorepo-template/tanstack-query.svg" alt="Measured on agentmods" height="20"></a>

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 415 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00000	$0.00415
Opus 5	$0.00000	$0.00208
Sonnet 5	$0.00000	$0.00083
Haiku 4.5	$0.00000	$0.00042

Measured 2d ago against content hash 4bd0c54bdc24, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

tanstack-query scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/frontend/tanstack-query.mdc · 20 lines

What it actually says

TanStack Query (v5) Rules

TanStack Query owns all server state. Depth: skill tanstack-query. This is a client SPA - ignore SSR/dehydrate/HydrationBoundary.

Repo invariants

Never fetch in useEffect + useState, and never mirror query data into local state.
Define queries with queryOptions() in src/services/worker-api/<feature>-query-options.ts next to <feature>.ts. Reuse the same object for useQuery / useSuspenseQuery / ensureQueryData / setQueryData - do not inline { queryKey, queryFn } at call sites.
Keys under the backend namespace, hierarchical (['worker-api','…']). Promote to a key factory once a feature has several related queries. Keys must be JSON-serializable.
queryFn delegates to fetchJsonWithSchema (forwards signal, throws on non-OK, validates with shared Zod - never as T). See contracts.mdc.
One module-singleton QueryClient in src/config/query-client.ts - never new QueryClient() in a component. Mount <ReactQueryDevtools> behind import.meta.env.DEV only.
Mutations: invalidate via invalidateQueries by default; full optimistic ritual only when needed (cancelQueries → snapshot → setQueryData → rollback → invalidateQueries).
Route loaders warm with ensureQueryData(opts); components read the same opts (see tanstack-router.mdc).

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2d ago First seen · 20 lines · 0 tokens per session scan A 4bd0c54bdc24

Subscribe to this mod's changes

tanstack-query is a cursor rule published in the GitHub repository louisbrulenaudet/monorepo-template (19 stars, last pushed 5d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 415 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

Backend and APIs Frontend React agent ai-agents claude-code cloudflare cloudflare-workers cursor

tanstack-query

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

What it actually says

TanStack Query (v5) Rules

Repo invariants

What this file has done since we first saw it

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