# Tanstack Svelte Query Best Practices

> TanStack Query conventions for reactive, cache-backed Svelte server state. Use when creating or reviewing Svelte queries, mutations, query keys, or cache updates.

- Skill: `bastidood/tanstack-svelte-query-best-practices` (Agent Skill, multi-file: 17 files)
- Install (CLI): `npx skillmds@latest add bastidood/tanstack-svelte-query-best-practices`
- Raw SKILL.md: https://api.skillmd.com/api/skills/bastidood/tanstack-svelte-query-best-practices/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Web & Frontend
- Author: BastiDood (https://skillmd.com/u/bastidood)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/bastidood/tanstack-svelte-query-best-practices

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# TanStack Svelte Query Best Practices

Treat server data as reactive cache state with explicit request ownership and cache identity; this produces clear query-state views and mutations that refresh only the data they affect.

## Library Sources

- GitHub repository ID: `TanStack/query`
- Context7 library ID: `/tanstack/query`
- DeepWiki repository ID: `TanStack/query`

Use Context7 for current documentation and DeepWiki for implementation details.

## References

Read the references that apply to the current task before writing or reviewing TanStack Svelte Query code.

1. Let TanStack Query own server-data lifecycle and reactive cache identity.
   - [Let TanStack Query own one server-data lifecycle](./references/request-ownership.md) instead of duplicating requests in effects or handlers.
   - [Include every response-changing input in cache identity](./references/query-keys.md) so filters, tenant, locale, and pagination cannot share stale results.
   - [Read request inputs exclusively from the query-function context](./references/query-function-inputs.md), never from captured request variables.
   - [Preserve missing required IDs](./references/absent-identifiers.md) and disable the request instead of issuing a fabricated empty-record request.
   - [Partition visibility-sensitive cache entries by non-secret actor identity](./references/actor-identity-and-secrets.md).
   - [Give `createQuery` an accessor for reactive query options](./references/reactive-query-options.md) so changing inputs update the query instead of freezing options.
2. Resolve query status before stateful presentation consumes data.
   - [Resolve pending, error, empty, and success states in an outer loader](./references/outer-loader.md) before mounting stateful presentation.
   - [Publish identity at the loader boundary through loader prop contracts](./references/loader-prop-contracts.md) and give resolved components only the data they need.
   - [Read query fields directly through reactive result consumption](./references/reactive-result-consumption.md), because destructuring snapshots their values.
3. Keep mutation lifecycle and invalidation scoped to the submitting operation.
   - [Choose one submission lifecycle](./references/mutation-form-integration.md); a form cannot simultaneously own SvelteKit enhancement and a client mutation.
   - [Pass changed operation input via mutation variables](./references/mutation-variables.md), keeping definition configuration stable.
   - [Put shared cache policy in the definition and component-specific UI work at the call site](./references/mutation-callback-ownership.md).
   - [Keep each invocation's success, failure, and settlement behavior at the mutation call site](./references/mutation-callsite-lifecycle.md), not an effect that loses invocation identity.
   - [Invalidate the narrow stale record or list family](./references/mutation-invalidation.md).