CSC Design System Skills & Best Practices
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Project Rules

Shared coding conventions for this repository, then the Next.js guidance that matches the installed version. Component restrictions, accessibility, responsive behavior, and code snippets stay in Standards & Best Practices.

Shared conventions

Project identityThis repository is the CSC design system. The web app is Next.js 15.5.27, React 19, and TypeScript strict, installed with npm workspaces. Routes live under app/(site). UI components come from @csc/ui.
Brand tokensBrand blue is #2A338F. Brand red is #EC1C2D. White text on a destructive action uses #C41222.
This Next.js installThere is no node_modules/next/dist/docs/ folder and no /_next/mcp endpoint. Do not upgrade Next.js to obtain them, and do not tell an agent those files exist.
Examples and claimsDo not put secrets, production records, or real personal data in examples, rules, or prompts. Do not claim a WCAG audit. Proposed CSC standards are not approved policy.
Load detail for the taskAGENTS.md stays short. Scoped notes live in .cursor/rules and .agents/skills. Read one when the task needs it.
After a code changeRun npx tsc --noEmit and npx vitest run.

Next.js guidance

These notes describe this App Router app on Next.js 15.5.27. They do not add login, and they do not point at a docs folder this install does not have.

ArchitectureKeep routes, layouts, and shared UI in the App Router structure of the application you are building.Server and Client ComponentsKeep client JavaScript on the interactive pieces.Data fetchingChoose freshness from the data, not from a single cache rule.Authentication and authorizationAuthorize on the server. A hidden button is not a permission.SecurityStop injection, secret leaks, and unsafe uploads in a government-facing application.PerformanceShip less client JavaScript and avoid waiting in series.AccessibilityUse the element, name, and focus treatment the standards describe. This page is not an audit.TestingCheck types and behavior before calling a screen done.DeploymentBuild the application that is configured. Do not add a host that was not requested.