React Components

Quick reference for building UI components with Atomic Design, shadcn/ui, and Radix UI. Each section summarizes the key rules — reference files provide full examples and edge cases.

Atomic Design

Five-level component hierarchy: Atoms → Molecules → Organisms → Templates → Pages.

Classification Quick Reference

Level	Breaks Down Further?	Fetches Data?	Business Logic?	Reusable?
Atom	No	No	No	Yes
Molecule	Into atoms	No	Minimal	Yes
Organism	Into molecules	Maybe	Yes	Usually
Template	Into organisms	No	No	Yes
Page	Into templates	Yes	Orchestration	No

Examples

• Atoms: Button, Input, Label, Avatar, Badge, Spinner, Separator
• Molecules: FormField (Label + Input + Error), SearchInput (Input + Button)
• Organisms: Header, SignUpForm, AppointmentCard, DoctorSearchResults
• Templates: MainLayout (Header + Sidebar + Content), AuthLayout
• Pages: DashboardPage, DoctorProfilePage (fetch data, wire to template)

Naming

• Component files: PascalCase — Button.tsx, FormField.tsx
• Directories: PascalCase — Button/, FormField/
• Tests: Button/__tests__/Button.test.tsx
• Barrel exports per level: atoms/index.ts

See references/atomic-design.md for classification decision table, naming conventions, barrel exports, and anti-patterns.

Shared vs App-Specific Components

Placement Rules

components/web/src/         → Shared across apps (@drzum/ui)
├── atoms/                  → @drzum/ui/atoms
├── molecules/              → @drzum/ui/molecules
├── organisms/              → @drzum/ui/organisms
├── templates/              → @drzum/ui/templates
└── chad-cn/                → Raw shadcn/ui copies

patient/src/components/     → Patient app only
├── atoms/
├── molecules/
├── organisms/
└── templates/

Decision flow:

1. Used by 2+ apps? → components/web/ (shared)
2. Used by 1 app? → {app}/src/components/ (app-specific)
3. Is a page? → {app}/src/pages/
4. Might become shared? → Start in the app, move later when needed

Import Convention

// ✅ Shared components
import { Button, Input } from "@drzum/ui/atoms";
import { FormField } from "@drzum/ui/molecules";

// ✅ App-specific components
import { AppointmentCard } from "@/components/organisms/AppointmentCard";

shadcn/ui

Copy-and-own component collection. Not a dependency — source code lives in your project.

Adding Components

pnpm dlx shadcn@latest add button input dialog

Customization

Modify the source directly — you own the code:

// Add a custom variant
const buttonVariants = cva("...", {
  variants: {
    variant: {
      default: "bg-primary text-primary-foreground hover:bg-primary/90",
      success: "bg-green-600 text-white hover:bg-green-700", // Custom
    },
  },
});

Theming

shadcn/ui uses CSS variables. Change your theme by updating variables in @theme:

@theme {
  --color-primary: #16a34a;
  --color-primary-foreground: #ffffff;
  --color-destructive: #dc2626;
}

Extending for Domain Use

Wrap shadcn components with domain-specific behavior:

function LoadingButton({ isLoading, children, ...props }: LoadingButtonProps) {
  return (
    <Button disabled={isLoading} {...props}>
      {isLoading && <Loader2 className="mr-2 size-4 animate-spin" />}
      {isLoading ? "Cargando..." : children}
    </Button>
  );
}

See references/shadcn-ui.md for setup, configuration, form patterns with React Hook Form, and monorepo placement.

Radix UI

Accessible, unstyled primitives that shadcn/ui builds on. Key concepts:

The asChild Pattern

// Merges Radix behavior onto YOUR component
<Dialog.Trigger asChild>
  <Button variant="outline">Abrir</Button>
</Dialog.Trigger>

Always use asChild when passing your own styled component as a Radix slot.

Data Attributes for Styling

Radix exposes state via data attributes — use them for Tailwind styling:

<Tabs.Trigger
  className="text-muted-foreground data-[state=active]:border-b-2 data-[state=active]:border-primary data-[state=active]:text-foreground"
>
  Tab
</Tabs.Trigger>

Common: data-[state=open], data-[state=active], data-[state=checked], data-[disabled]

Common Primitives

Primitive	Use For	Key Behavior
Dialog	Modals, confirmations	Focus trap, Escape to close
DropdownMenu	Context menus	Arrow key navigation, type-ahead
Tabs	Tabbed content	Arrow keys between triggers
Select	Selection from options	Keyboard navigation, type-ahead
Tooltip	Hover information	Delay, accessible labels
Accordion	Collapsible sections	Single or multiple open

Accessibility Checklist

1. Always include Dialog.Title (use VisuallyHidden if not visible)
2. Use asChild to avoid nesting <button> inside <button>
3. Provide aria-label for icon-only triggers
4. Test with keyboard: Tab, Escape, arrow keys, Enter/Space

See references/radix-ui.md for Dialog, Dropdown, Tabs, Select, Tooltip examples and anti-patterns.

Responsive Design

Mobile-first: base styles are mobile, breakpoints add larger-screen overrides.

Breakpoints

Prefix	Min Width	Target
(none)	0px	Mobile (base)
sm:	640px	Large phones
md:	768px	Tablets
lg:	1024px	Laptops
xl:	1280px	Desktops

Common Patterns

{/* Stack → Row */}
<div className="flex flex-col gap-4 sm:flex-row">{/* ... */}</div>

{/* Responsive grid */}
<div className="grid grid-cols-1 gap-4 sm:grid-cols-2 lg:grid-cols-3">{/* ... */}</div>

{/* Show/hide */}
<nav className="hidden lg:block">{desktopNav}</nav>
<button className="lg:hidden">{hamburger}</button>

Touch Targets

Minimum 44x44px for interactive elements on mobile. Use h-11 (44px) as minimum button height.

Rules

• Start mobile — Write base styles for the smallest screen
• Add up — Use sm:, md:, lg: to progressively enhance
• Prefer CSS breakpoints — Use useMediaQuery only when component trees differ, not just layout
• Test on real devices — Don't rely only on browser DevTools resize

See references/responsive-design.md for responsive tables, container queries, touch targets, and testing patterns.

Form Element Styling

When styling form elements, follow the project's design system:

• Focus ring: focus-visible:border-primary focus-visible:ring-2 focus-visible:ring-primary/30 — green glow effect
• Default borders: border-border — light, subtle
• Error state: border-destructive focus-visible:ring-destructive/30
• Disabled: disabled:cursor-not-allowed disabled:opacity-50

Reference .molcajete/research/ui-ideas/form-ui.png for the desired look and feel.

Reference Files

File	Description
references/atomic-design.md	Five-level hierarchy, classification checklists, naming, barrel exports
references/shadcn-ui.md	Setup, adding components, customization, cva variants, theming
references/radix-ui.md	Dialog, Dropdown, Tabs, Select, Tooltip, accessibility
references/responsive-design.md	Mobile-first breakpoints, responsive patterns, touch targets, container queries