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Use this skill when implementing security in frontend applications: XSS prevention, CSP, input sanitization, CORS, secure token storage (httpOnly cookies in Next.js, in-memory for SPA), security headers, env vars, and cross-reference with GRC skills.
Codex または Claude でインストール この Prompt をコピーして Codex、Claude、または他のアシスタントに貼り付けると、Skill ページを確認してインストールできます。
SOC 職業分類に基づく
Use this skill when working on frontend. Orchestrates specialized sub-skills covering architecture, components, rendering, styles, data fetching, testing, performance, and security. Stack: React 19+, Next.js 15+, Vite 6+, TypeScript strict, Tailwind CSS, pnpm.
Use this skill as the entry point for every software development task. Routes the agent to the correct sub-skills based on context: frontend, backend, architecture, CI/CD, Docker, Git, scripting and TypeScript. Automatically activates cross-cutting skills (clean-code-principles, typescript-patterns, git-usage) that must be present in every code interaction.
Usa esta skill cuando trabajes en frontend. Orquesta sub-skills especializadas que cubren arquitectura, componentes, rendering, estilos, data fetching, testing, performance y seguridad. Stack: React 19+, Next.js 15+, Vite 6+, TypeScript strict, Tailwind CSS, pnpm.
Usa esta skill como punto de entrada para toda tarea de desarrollo de software. Enruta al agente hacia las sub-skills correctas según el contexto: frontend, backend, architecture, CI/CD, Docker, Git, scripting y TypeScript. Activa automáticamente skills transversales (clean-code-principles, typescript-patterns, git-usage) que deben estar presentes en toda interacción de código.
Use this skill ALWAYS before adding, updating, or removing any dependency in a Node.js project. Applies to frontend, backend, and monorepos. Covers mandatory pnpm usage, exact pinning without carets, querying the latest stable version, post-install auditing, protection against compromised packages with free tools, and Dependabot for controlled updates.
Usa esta skill SIEMPRE antes de añadir, actualizar o eliminar cualquier dependencia en un proyecto Node.js. Aplica a frontend, backend y monorepo. Cubre pnpm obligatorio, pin exact sin carets, consulta de última versión estable, auditoría post-instalación, protección contra paquetes comprometidos con herramientas gratuitas, y configuración de Dependabot para actualizaciones controladas.
| name | security-rules |
| description | Use this skill when implementing security in frontend applications: XSS prevention, CSP, input sanitization, CORS, secure token storage (httpOnly cookies in Next.js, in-memory for SPA), security headers, env vars, and cross-reference with GRC skills. |
| Skill | When to activate |
|---|---|
owasp-top-10 | Always in any frontend development handling user input or authentication. |
gdpr | When the frontend captures personal data, implements tracking cookies, or consent. |
ccpa-cpra | When implementing data sale/sharing opt-out or detecting the browser GPC signal. |
fetching-rules | When the frontend makes HTTP calls — contains the apiClient implementation (token injection, auto-clear 401, typed ApiError). It is the single source of truth for the API client. |
next.config (section 3).dangerouslySetInnerHTML only with DOMPurify. Validate href against javascript: (section 1).governance-risk-and-compliance → owasp-top-10 for vulnerability checklist.NEXT_PUBLIC_* or VITE_* (section 7).// React escapes HTML by default — safe against XSS
function UserGreeting({ name }: { name: string }) {
return <p>Hello, {name}</p>;
}
// If you NEED to render HTML (markdown, CMS), sanitize with DOMPurify:
import DOMPurify from 'dompurify';
function SafeContent({ html }: { html: string }) {
const sanitized = DOMPurify.sanitize(html, {
ALLOWED_TAGS: ['p', 'b', 'i', 'em', 'strong', 'a', 'ul', 'ol', 'li', 'br'],
ALLOWED_ATTR: ['href', 'target', 'rel'],
});
return <div dangerouslySetInnerHTML={{ __html: sanitized }} />;
}
// Validate href to prevent javascript: protocol
function SafeLink({ href, children }: { href: string; children: ReactNode }) {
const isValid = /^https?:\/\//.test(href) || href.startsWith('/');
if (!isValid) {
return <span>{children}</span>;
}
return (
<a href={href} rel="noopener noreferrer" target="_blank">
{children}
</a>
);
}
import { NextRequest, NextResponse } from 'next/server';
export function middleware(request: NextRequest) {
const nonce = Buffer.from(crypto.randomUUID()).toString('base64');
const csp = [
`default-src 'self'`,
`script-src 'self' 'nonce-${nonce}' 'strict-dynamic'`,
`style-src 'self' 'unsafe-inline'`,
`img-src 'self' blob: data: https:`,
`font-src 'self'`,
`connect-src 'self' ${process.env.NEXT_PUBLIC_API_URL}`,
`frame-ancestors 'none'`,
`base-uri 'self'`,
`form-action 'self'`,
].join('; ');
const response = NextResponse.next();
response.headers.set('Content-Security-Policy', csp);
response.headers.set('x-nonce', nonce);
return response;
}
// Pass nonce to Scripts
import { headers } from 'next/headers';
import Script from 'next/script';
export default async function RootLayout({ children }: { children: ReactNode }) {
const headersList = await headers();
const nonce = headersList.get('x-nonce') ?? '';
return (
<html lang="en">
<body>
{children}
<Script src="https://analytics.example.com/script.js" nonce={nonce} />
</body>
</html>
);
}
const securityHeaders = [
{
key: 'X-DNS-Prefetch-Control',
value: 'on',
},
{
key: 'Strict-Transport-Security',
value: 'max-age=63072000; includeSubDomains; preload',
},
{
key: 'X-Frame-Options',
value: 'DENY',
},
{
key: 'X-Content-Type-Options',
value: 'nosniff',
},
{
key: 'Referrer-Policy',
value: 'strict-origin-when-cross-origin',
},
{
key: 'Permissions-Policy',
value: 'camera=(), microphone=(), geolocation=(self)',
},
];
export default {
async headers() {
return [
{
source: '/(.*)',
headers: securityHeaders,
},
];
},
};
// Auth tokens in httpOnly cookies (NOT localStorage)
import { cookies } from 'next/headers';
export async function loginAction(formData: FormData) {
const response = await authApi.login({
email: formData.get('email') as string,
password: formData.get('password') as string,
});
const cookieStore = await cookies();
cookieStore.set('session', response.token, {
httpOnly: true,
secure: true,
sameSite: 'lax',
maxAge: 60 * 60 * 24,
path: '/',
});
}
Never store tokens in localStorage, sessionStorage, cookies without httpOnly, or URL query params. Implement refresh token rotation: if a refresh token is used twice, invalidate all user tokens.
In a pure SPA where you don't control the server (can't set httpOnly cookies), the token is stored in memory (JavaScript variable, signal, or state store). This is more secure than localStorage because:
document.cookie or localStorage.getItem()// features/auth/services/auth.service.ts
import { signal } from '@preact/signals-react';
interface AuthState {
token: string | null;
user: { id: string; email: string; name: string } | null;
}
// Token lives ONLY in memory — lost on close/refresh
const authState = signal<AuthState>({ token: null, user: null });
export function setAuth(token: string, user: AuthState['user']) {
authState.value = { token, user };
}
export function clearAuth() {
authState.value = { token: null, user: null };
}
export function getToken(): string | null {
return authState.value.token;
}
The full apiClient implementation (with typed ApiError, token injection, auto-clear on 401, and error normalization) is in fetching-rules §6. It is the single source of truth for the API client — do not duplicate here.
Key SPA rule: The in-memory token is lost on page refresh. If the API supports refresh tokens, implement an endpoint that returns a new access token via httpOnly cookie (set from the backend). If there's no refresh token, the user must re-authenticate.
import { z } from 'zod';
// Shared schema (client + server)
export const commentSchema = z.object({
content: z
.string()
.min(1, 'Comment cannot be empty')
.max(2000, 'Maximum 2000 characters')
.transform((val) => val.trim()),
parentId: z.string().uuid().optional(),
});
// Server Action — ALWAYS re-validate
export async function createComment(_: unknown, formData: FormData) {
const parsed = commentSchema.safeParse({
content: formData.get('content'),
parentId: formData.get('parentId'),
});
if (!parsed.success) {
return { errors: parsed.error.flatten().fieldErrors };
}
// parsed.data is safe — inferred type + sanitized
await db.comment.create({ data: parsed.data });
}
const ALLOWED_ORIGINS = [
process.env.NEXT_PUBLIC_APP_URL!,
];
export async function OPTIONS(request: Request) {
const origin = request.headers.get('origin');
if (!origin || !ALLOWED_ORIGINS.includes(origin)) {
return new Response(null, { status: 403 });
}
return new Response(null, {
status: 204,
headers: {
'Access-Control-Allow-Origin': origin,
'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
'Access-Control-Allow-Headers': 'Content-Type, Authorization',
'Access-Control-Max-Age': '86400',
},
});
}
import { z } from 'zod';
const envSchema = z.object({
DATABASE_URL: z.string().url(),
NEXTAUTH_SECRET: z.string().min(32),
NEXT_PUBLIC_API_URL: z.string().url(),
});
export const env = envSchema.parse(process.env);
Rules: NEXT_PUBLIC_* is visible on client (never secrets), without prefix is server only. Validate with Zod at startup (fail fast). .env.local in .gitignore, .env.example committed.
dangerouslySetInnerHTML with user input without DOMPurify = direct XSS.eval(), new Function(), innerHTML with dynamic data = attack vector.Access-Control-Allow-Origin: '*' in production exposes the API to any origin.localhost:5173 while the API typically runs on localhost:3000. CORS will block requests unless the API configures the correct origin (e.g., CORS_ORIGIN=http://localhost:5173). Do not use Vite's proxy as a production workaround — configure CORS correctly in the backend.NEXT_PUBLIC_* are exposed in the client bundle.target="_blank" without rel="noopener noreferrer".console.log of sensitive data in production.