Shadcn Guideline: Setup — Initialize project properly. Description: Run init command to set up components.json and globals.css. Do: npx shadcn@latest init before adding components. Don't: Skip init and add components directly. Good Example: npx shadcn@latest init. Bad Example: npx shadcn@latest add button (without init). Severity: High. Docs: https://ui.shadcn.com/docs/installation.