React Modern

What it does

When your agent uses it

• Debugging React components and hooks — state
• Server and Client Components — in whatever React setup the project uses

Example prompts

• “component”
• “useState”
• “useEffect”
• “/react-modern”

Workflow steps

9 steps, taken from the first numbered list in SKILL.md.

1. 1Match the setup. Server Components, 'use client', and server actions exist
2. 2Derive, don't sync. If a value can be computed from props or state during
3. 3Effects are for synchronizing with external systems (subscriptions, DOM
4. 4Every effect that subscribes or starts work returns a cleanup, and every
5. 5Never mutate state or props; update with new objects and arrays.
6. 6Keys are stable identities from the data — never array indexes for lists
7. 7Memoize after measuring, or not at all when the React Compiler is enabled.
8. 8Follow the framework's file conventions over style preferences — Next.js
9. 9Accessible by default: semantic elements, labels on inputs, keyboard

What it can do on your machine

Read from SKILL.md and the folder at commit 57f6018. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

React Modern loads about 1.7k tokens when it runs. Until then it costs about 101 tokens; SKILL.md has 574 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~101

When it runs · the whole SKILL.md, loaded when a task matches

~1.7k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from WrongStack/WrongStack at commit 57f6018, republished under its MIT licence (© WrongStack). 574 words, ~1,655 tokens.

name

react-modern

description

Use this skill when writing, reviewing, or debugging React components and hooks — state, effects, data fetching, forms, Server and Client Components — in whatever React setup the project uses. Triggers: user mentions "React", "component", "hook", "useState", "useEffect", "re-render", "Server Component", "use client", "Suspense", "useTransition", "useActionState", "Next.js", "JSX", "TSX".

version

2.0.0

required-capabilities

filesystem.read, filesystem.write

optional-capabilities

verification.run, browser.interact

// Derived value — no state, no effect.
function Cart({ items }: { items: CartItem[] }) {
  const total = items.reduce((sum, item) => sum + item.price * item.qty, 0);
  return <p>Total: {formatMoney(total)}</p>;
}

// Effect that syncs with an external system, with cleanup.
function useOnlineStatus(): boolean {
  const [online, setOnline] = useState(() => navigator.onLine);
  useEffect(() => {
    const update = () => setOnline(navigator.onLine);
    window.addEventListener('online', update);
    window.addEventListener('offline', update);
    return () => {
      window.removeEventListener('online', update);
      window.removeEventListener('offline', update);
    };
  }, []);
  return online;
}

// Client-only fetch without a data library: abort stale requests.
function useUser(id: string) {
  const [state, setState] = useState<{ user?: User; error?: Error }>({});
  useEffect(() => {
    const controller = new AbortController();
    fetchUser(id, controller.signal)
      .then((user) => setState({ user }))
      .catch((error: Error) => {
        if (error.name !== 'AbortError') setState({ error });
      });
    return () => controller.abort();
  }, [id]);
  return state;
}

// RSC frameworks only: server data in a Server Component, interactivity in a leaf.
export default async function ProfilePage({ params }: { params: Promise<{ id: string }> }) {
  const { id } = await params;
  const user = await getUser(id); // runs on the server
  return <ProfileHeader user={user} />;
}

// React 19 form action with pending and error state.
'use client';
function RenameForm({ rename }: { rename: (prev: State, data: FormData) => Promise<State> }) {
  const [state, action, pending] = useActionState(rename, { error: null });
  return (
    <form action={action}>
      <label htmlFor="name">Name</label>
      <input id="name" name="name" required />
      <button type="submit" disabled={pending}>Save</button>
      {state.error ? <p role="alert">{state.error}</p> : null}
    </form>
  );
}

© WrongStack, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file in packages/core/skills/react-modern of WrongStack/WrongStack.

• SKILL.md
• SKILL.save.md

Open the folder on GitHubat commit 57f6018