react

React development rules for frontend projects using React 19, TypeScript, Tailwind CSS, and ShadCN components. They also set conventions for components, files, mock data, forms, and styling.

In plain words
What is it for?
Building React pages and components, structuring workflow files, handling loading states, using hooks and form tools, and styling with the project's component library.
Why use it?
They keep frontend code organized and consistent, and clarify which UI files should not be edited.

Cursor rule for Cursor

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/iloveitaly/llm-ide-rules/react
Clone the repo
git clone --depth 1 https://github.com/iloveitaly/llm-ide-rules

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 1,042 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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.01042
Opus 5 $0.00000 $0.00521
Sonnet 5 $0.00000 $0.00208
Haiku 4.5 $0.00000 $0.00104

Measured 2d ago against content hash 0f81a35b1c07, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

react 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/react.mdc · 107 lines

How it starts

The opening of the file, as written. The whole thing — 107 lines — stays where its author put it; the contents beside it link to each section on GitHub.

React

  • You are using the latest version of React (v19)
  • Do not write any backend code. Just frontend logic.
  • If a complex skeleton is needed, create a component function LoadingSkeleton in the same file.
  • Store components for each major page or workflow in app/components/$WORKFLOW/$COMPONENT.tsx.
    • If a single page has more than two dedicated components, create a subfolder app/components/$WORKFLOW/$PAGE/$COMPONENT.tsx
  • Use lowercase dash separated words for file names.
  • Use React 19, TypeScript, Tailwind CSS, and ShadCN components.
  • Prefer function components, hooks over classes.
  • Use ShadCN components in web/app/components/ui as your component library. If you need new components, ask for them.
  • Break up large components into smaller components, but keep them in the same file unless they can be generalized.
  • Put any "magic" strings like API keys, hosts, etc into a "constants.ts" file.
  • For React functional components with three or fewer props, always inline the prop types as an object literal directly in the function signature after the destructured parameters (e.g., function Component({ prop1, prop2 }: { prop1: string; prop2?: number }) { ... }). Include default values in destructuring and mark optional props with ? in the type object. Do not use separate interfaces or type aliases; keep types inline. For complex types, add inline comments if needed.
  • Put the interface definition right above the related function
  • Internally, store all currency values as integers and convert them to floats when rendering visually
  • When building forms use React Hook Form.
  • Include a two line breaks between any useHook() calls and any useState() definitions for a component.
  • When using a function prop inside a useEffect, please use a pattern that avoids including the function in the dependency array, like the useRef trick.
  • When writing React components, always hoist complex conditional expressions into descriptively named constants at the top of the component function for better readability and maintainability.
  • When managing API response data, store the entire response object (or relevant subset) in a single useState rather than creating separate state variables for each field. Derive individual values from the response object when passing to child components using optional chaining (e.g., response?.field || defaultValue).
  • Refactor ternary to &&: {condition ? <A/> : <B/>}{condition && <A/>}{!condition && <B/>}
  • Use the following pattern to reference query string values (i.e. ?theQueryStringParam=value):
const [searchParams, _setSearchParams] = useSearchParams();
// searchParams contains the value of all query string parameters
const queryStringValue = searchParams.get("theQueryStringParam")

Read the full file on GitHub · 107 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.

  1. 2d ago First seen · 107 lines · 1,042 tokens per session scan A 0f81a35b1c07

Subscribe to this mod's changes

react is a cursor rule published in the GitHub repository iloveitaly/llm-ide-rules (13 stars, last pushed 2d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,042 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.