What is tanstack-start?

Rules for building TanStack Start applications, a web framework that provides file-based routing, data loading, and server-side functions.

Creating routes and nested layouts, loading route data, guarding pages, validating search values, and connecting pages to backend functions.

They keep routes, data fetching, authentication checks, search parameters, and backend logic organised and consistently validated.

tanstack-start — Cursor rule for Cursor by virastack/ai

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.

Clone the repo

git clone --depth 1 https://github.com/virastack/ai

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/virastack/ai/tanstack-start/github.svg)](https://agentmods.dev/rules/virastack/ai/tanstack-start)

Your own site

<a href="https://agentmods.dev/rules/virastack/ai/tanstack-start"><img src="https://agentmods.dev/badge/rules/virastack/ai/tanstack-start/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/rules/virastack/ai/tanstack-start"><img src="https://agentmods.dev/badge/rules/virastack/ai/tanstack-start.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

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

When invoked 1,057 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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	$0.01057
Opus 5.5	$0.00000	$0.00423
Sonnet 5.5	$0.00000	$0.00211
Haiku 4.5	$0.00000	$0.00106

Measured 1mo ago against content hash 54bdedbcb46a, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

tanstack-start 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 1mo 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

tanstack-start — 95% identical, 18 lines differ

templates/tanstack/.cursor/rules/tanstack-start.mdc · 105 lines

How it starts

The opening of the file, as written. The whole thing — 105 lines — stays where its author put it; the contents beside it link to each section on GitHub.

TanStack Start Constitution

Constraints

Route Definition: Always use createFileRoute. Path MUST strictly match the file system location.
Component Scope: Keep route files thin. Only orchestrate routing and data. Move UI and business logic to src/features.
Nested Layouts: Use the <Outlet /> component in parent routes to render child routes. If a route has children, the parent component MUST render <Outlet />.
Data Loading: Fetch all route-level data in loader. Consume via Route.useLoaderData or useSuspenseQuery.
Guards: Put auth, redirects, and preconditions in beforeLoad.
Hydration: Rely on loader prefetching for data hydration. Do not use Next.js-specific patterns like manual dehydration.
Server Functions: Wrap all backend-only logic in standalone serverFn. Functions MUST act as a bridge to the API layer; keep database orchestration and business logic inside src/features/api or helpers.
Search Params: Validate all search params with validateSearch using a Zod schema. Never trust raw search values.
i18n Implementation: Use paraglide-js for translations. Follow the patterns defined in i18n.mdc.
Error Handling: Provide errorComponent for failure states. Handle expected errors in the loader.
Loading UI: Provide pendingComponent for async states when needed.
Not Found: Provide notFoundComponent for missing resources.
Head/SEO: Define metadata with the head property. Keep it deterministic and typed.
Sync: Ensure route paths are kept in sync via tsr watch command.
Guard Security: Enforce session and permission checks within beforeLoad or dedicated middleware before serverFn execution.

Bans

Client-Side Fetching: Fetching data inside the component body via useEffect or useQuery (without loader prefetch) is FORBIDDEN.
Inline serverFn: Defining serverFn inside a component or route definition is FORBIDDEN. They MUST be exported as standalone constants.
Next.js Conventions: Using "use server" directives, page.tsx naming, or Next.js-specific hooks (useRouter from next/navigation) is STRICTLY FORBIDDEN.
Untyped Routes: Navigating via string paths without type-safety (using Link or Maps without the to property pointing to a valid route) is FORBIDDEN.
Insecure Env Vars: Forbidden to store secrets or private keys in environment variables with VITE_ prefixes.

Read the full file on GitHub · 105 lines

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.

1mo ago First seen · 105 lines · 0 tokens per session scan A 54bdedbcb46a

Subscribe to this mod's changes

tanstack-start is a cursor rule published in the GitHub repository virastack/ai (23 stars, last pushed 2mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,057 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 2026-08-30.

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tanstack-start