react-core

react-core is a skill for Claude Code, Codex from adonai-labs/agent-runway. It costs 89 tokens per session (729 once invoked), scanned A, original, MIT.

React implementation guidance for project structure, components, hooks, shared state, testing, security, accessibility, and performance in React 18 and later.

In plain words
What is it for?
Use it to organise React features, decide how state should be shared, design components and hooks, test interfaces, and improve accessibility or performance.
Why use it?
It helps developers make practical React design decisions without adding structure or optimisation before the application needs it.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Claude Code.

Good fit Use it to organise React features, decide how state should be shared, design components and hooks, test interfaces, and improve accessibility or performance.

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Install with agentmods
npx agentmods add skills/adonai-labs/agent-runway/skill-react-core
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.

Any agent
npx skills add adonai-labs/agent-runway --skill skill-react-core
Clone the repo
git clone --depth 1 https://github.com/adonai-labs/agent-runway

Made for: Claude Code, Codex.

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.

agentmods badge for react-core

README.md
[![agentmods](https://agentmods.dev/badge/skills/adonai-labs/agent-runway/skill-react-core.svg)](https://agentmods.dev/skills/adonai-labs/agent-runway/skill-react-core)
Your own site
<a href="https://agentmods.dev/skills/adonai-labs/agent-runway/skill-react-core"><img src="https://agentmods.dev/badge/skills/adonai-labs/agent-runway/skill-react-core.svg" alt="Measured on agentmods" height="20"></a>
Per session 89 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 729 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00089 $0.00729
Opus 5 $0.00044 $0.00365
Sonnet 5 $0.00018 $0.00146
Haiku 4.5 $0.00009 $0.00073

Measured 4d ago against content hash 86b347c36ab9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

react-core 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 4d 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.

src/stacks/react/skill-react-core/SKILL.md · 69 lines

How it starts

The opening of the file, as written. The whole thing — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.

React Core

How to invoke

After agent-runway add react, the skill is installed at .cursor/skills/react-core/. Use:

  • Cursor: @react-core or ask a React question while editing *.tsx / *.jsx (rules auto-attach)
  • Claude Code: reference .agent-runway/skills/react-core/SKILL.md or ask in context of React files

Examples:

  • How should I structure this feature's components?
  • When should I use context vs Zustand vs React Query?
  • How do I test this hook without rendering a component?
  • Is this memoisation justified?

Not sure which skill to use? Start with /start — it classifies intent and routes to the right skill.


Guiding principles

Simplicity first. React's mental model is already a good guide — follow it rather than fighting it.

  • Start with the simplest state and structure that works; add layers only when complexity demands it
  • Composition over configuration; small, focused components over large multi-responsibility ones
  • SOLID applies: SRP means one reason to render, DIP via props and hooks rather than direct coupling
  • DRY for business logic in hooks and services; duplication in JSX is often acceptable
  • Measure before memoising — React.memo, useMemo, and useCallback have a cost; profile first
  • Accessibility is not optional — semantic HTML and ARIA are part of the implementation, not an afterthought

What this skill helps with

  • Project and feature structure scaled to complexity
  • Component patterns — functional, composition, compound, controlled/uncontrolled
  • State management decisions — local state, context, Zustand, React Query
  • Custom hooks — extracting logic, cleaning up, dependency management
  • Testing with React Testing Library — components, hooks, context, async
  • Security: XSS, dangerouslySetInnerHTML, input validation
  • Accessibility: semantic HTML, ARIA, keyboard navigation, focus management
  • Performance: memoisation strategy, code splitting, virtualisation

Skill files

File Contents
architecture.md Project structure, feature organisation, routing, naming
patterns.md Component patterns, hooks, state management decisions
testing.md RTL setup, component tests, hook tests, MSW, accessibility
security.md XSS, CSP, input validation, dependency audit
observability.md Error boundaries, logging, performance monitoring
reference.md Toolchain, Vite config, common commands

Read the full file on GitHub · 69 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 4d ago First seen · 69 lines · 89 tokens per session scan A 86b347c36ab9

Subscribe to this mod's changes

react-core is a skill published in the GitHub repository adonai-labs/agent-runway (2 stars, last pushed 18d ago), licensed MIT. It adds 89 tokens to every session and 729 once invoked, about $0.0004 per session on Opus 5. 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.

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