lifeforge/instructions/ui-guide.md

LifeForge Frontend UI Library Architecture & Usage Guide

Welcome to the LifeForge UI Library Guide. This document serves as the single source of truth for frontend development in the LifeForge ecosystem. Anyone writing frontend code for LifeForge must read this guide from cover to cover before writing a single line of code.

---

1. Core Philosophy & Architectural Overview

The LifeForge UI library is built on a zero-runtime CSS-in-JS architecture powered by Vanilla Extract and Sprinkles. This provides total type safety, compile-time optimization, and rich theme integration without the performance overhead of traditional CSS-in-JS solutions.

Two Strict Rules

Important

RULE 1: NO TAILWINDCSS AT ALL
Tailwind classes must never be written in frontend component code. All layout, spacing, typography, and styling must be declared using the custom primitives and high-level components supplied by this library.

Important

RULE 2: NO INLINE STYLES FOR CORE LAYOUT & DESIGN
Custom inline style objects must be avoided. If a style can be represented through component props or tokens, you must use those props. Inline styles are reserved solely for truly dynamic runtime calculations (e.g., coordinates from drag-and-drop events).

Design Tokens & Dynamic Scaling

The design system defines global tokens under vars (compiled to CSS variables) that automatically scale with user personalisation settings:

• Font Scale (--custom-font-scale): Scales typography and padding/margin dynamically.
• Border Radius Multiplier (--custom-border-radius-multiplier): Auto-scales corners from sharp to pill-like.
• Custom Themes (.theme-[color] & .bg-[palette]): Sets theme shades for brand colors (--color-custom-*) and background palettes (--color-bg-* like slate, zinc, neutral, mauve, olive, mist, taupe).

---

2. Global Token Systems

All standard layout and typography options are referenced via type-safe tokens exported by the system.

A. Spacing & Margin/Padding Tokens

Spacing scales are defined under vars.space and scale with font size to keep visual rhythm:

• none: '0'
• xs: calc(var(--spacing) * 1) (equivalent to 4px base)
• sm: calc(var(--spacing) * 2) (8px base)
• md: calc(var(--spacing) * 4) (16px base)
• lg: calc(var(--spacing) * 6) (24px base)
• xl: calc(var(--spacing) * 8) (32px base)
• 2xl: calc(var(--spacing) * 12) (48px base)
• 3xl: calc(var(--spacing) * 16) (64px base)

B. Border Radius (Rounding) Tokens

Border corners are defined under vars.radii and scale with the user's corner multiplier:

• none: '0'
• sm: var(--radius-sm)
• md: var(--radius-md)
• lg: var(--radius-lg)
• xl: var(--radius-xl)
• 2xl: var(--radius-2xl)
• 3xl: var(--radius-3xl)
• full: '9999px'

C. Typography Scales

Typography values scale with --custom-font-scale:

Size Token	Font Size (fontSize)	Line Height (lineHeight)
xs	var(--text-xs)	var(--text-xs--line-height)
sm	var(--text-sm)	var(--text-sm--line-height)
base	var(--text-base)	var(--text-base--line-height)
lg	var(--text-lg)	var(--text-lg--line-height)
xl	var(--text-xl)	var(--text-xl--line-height)
2xl	var(--text-2xl)	var(--text-2xl--line-height)
3xl	var(--text-3xl)	var(--text-3xl--line-height)
4xl	var(--text-4xl)	var(--text-4xl--line-height)
5xl	var(--text-5xl)	1
6xl	var(--text-6xl)	1
7xl	var(--text-7xl)	1
8xl	var(--text-8xl)	1
9xl	var(--text-9xl)	1

Font Weights:

• normal: '400'
• medium: '500'
• semibold: '600'
• bold: '700'

---

3. Style Resolution & The Styling Engine

LifeForge uses a custom styling resolver, resolveStyles(), which translates token-based properties and responsive objects into static class names and CSS custom properties at runtime.

A. Color Properties & State Resolvers

Colors in LifeForge are resolved through an arbitrary CSS variable architecture that handles dynamic user personalization and interactions. The primary color properties are:

• bg: Background Color (--lf-bg)
• color: Text/Foreground Color (--lf-color)
• borderColor: Border Color (--lf-border-color)
• ringColor: Focus Ring Color (--lf-ring-color)
• ringOffsetColor: Offset Ring Color (--lf-ring-offset-color)
• divideColor: Dividing Line Color (--lf-divide-color)

Supported Color Keys

1. Base Palette: transparent, dangerous (#ef4444), muted (mid-gray), primary (user-accented), inherit, custom-50 to custom-900 (accent shades), and bg-50 to bg-950 (system background shades).
2. Tailwind Palette Names: Colors like red-500, blue-600, emerald-400 map directly to tailwind shades.
3. Color with Opacity: Zero-runtime opacity can be added using the colorWithOpacity(token, opacityValue) utility.

Theme & State Specific Variants

Any color prop can receive a static color value or a map of conditions representing interactive states:

type ThemeConditionPropName =
  | 'base' // Default style
  | 'dark' // Dark mode
  | 'hover' // Hover state
  | 'darkHover' // Hover state in dark mode
  | 'hasBgImage' // Active when page has a background image
  | 'darkHasBgImage' // Active in dark mode with a background image
  | 'hasBgImageHover'
  | 'hasBgImageDarkHover'

Example Usage:

<Box
  bg={{
    base: 'bg-50',
    dark: 'bg-900',
    hover: 'bg-200',
    darkHover: 'bg-800'
  }}
  color={{ base: 'bg-950', dark: 'bg-50' }}
/>

Pre-built Surface Presets (surface)

The most common background patterns are available as a pre-built surface object exported from @lifeforge/ui:

import { surface } from '@lifeforge/ui'

// Light static surface — for non-interactive light backgrounds
surface.light
// => { base: 'bg-100', dark: 'bg-800' }

// Light interactive surface — for controls (Listbox, SearchInput, selectable Cards)
surface.lightInteractive
// => { base: 'bg-100', hover: 'bg-200', dark: 'bg-800', darkHover: colorWithOpacity('bg-700', '50%') }

// Default surface — for static Cards
surface.default
// => { base: 'bg-50', dark: 'bg-900' }

// Default interactive surface — for clickable Cards
surface.defaultInteractive
// => { base: 'bg-50', dark: 'bg-900', hover: 'bg-100', darkHover: 'bg-800' }

These are as const objects that can be spread or passed directly into the bg prop:

<Listbox bg={surface.lightInteractive} ... />
<Card bg={surface.lightInteractive} ... />    {/* Override Card's default */}
<Card isInteractive ... />                    {/* Uses surface.defaultInteractive automatically */}

The surface.default and surface.defaultInteractive presets already serve as the built-in defaults for the Card component — you only need to pass them explicitly when overriding or when using them on non-Card primitives.

B. Opacity Modifiers (colorWithOpacity)

To prevent heavy runtimes, colors can be blended with transparency using CSS color-mix through the colorWithOpacity helper:

import { colorWithOpacity } from '@lifeforge/ui'

// Generates: color-mix(in srgb, var(--color-custom-500) 30%, transparent)
const semiTransparentPrimary = colorWithOpacity('primary', '30%')

Supported Opacity Levels: '5%', '10%', '20%', '30%', '40%', '50%', '60%', '70%', '80%', '90%'.

colorWithOpacity can be used directly in the bg prop — no inline style needed:

<Flex
  align="center"
  bg={colorWithOpacity('custom-500', '20%')}
  justify="center"
  p="md"
  r="md"
>
  <Icon color="custom-500" icon="tabler:box" />
</Flex>

This replaces the old pattern of inline style={{ backgroundColor: 'color-mix(...)' }}.

C. Responsive Properties & Breakpoints

Layout props support responsive values. Breakpoints are defined as:

• base: Mobile first (default, no media query)
• sm: @media (min-width: 640px)
• md: @media (min-width: 768px)
• lg: @media (min-width: 1024px)
• xl: @media (min-width: 1280px)
• 2xl: @media (min-width: 1536px)

Any responsive property accepts a scalar or a responsive configuration object:

// Single width everywhere
<Box width="100%" />

// Responsive width
<Box width={{ base: '100%', md: '50%', lg: '33.33%' }} />

How it works under the hood: The engine applies .lf-w and .md:lf-w classes while defining CSS variables (--lf-w: 100%, --lf-w-md: 50%) inline, keeping output stylesheet sizes extremely small.

---

4. The Core Primitives

Primitives are the architectural blocks from which all higher-level views are constructed. They all support as and asChild composition.

graph TD
    Slot[Slot / asChild Pattern] --> Box
    Box --> Flex
    Box --> Grid
    Flex --> Stack
    Box --> Bordered
    Box --> Ring
    Box --> Text
    Text --> Icon
    Slot --> WithDivide
    Slot --> Transition

---

A. Box

The foundational primitive. Renders a div by default. It manages spacing, padding, basic layout variables, borders, and rounded corners.

interface BoxOwnProps<T extends ElementType = 'div'> {
  as?: T                     // Semantic tag override (e.g. 'section', 'form')
  asChild?: boolean          // Radix Slot composition
  display?: ResponsiveProp<'block' | 'inline' | 'inline-block' | 'none' | 'contents'>
  bg?: ThemeConditionProp<ColorValue>
  shadow?: boolean           // Applies smooth global card shadow (deactivated in dark mode)

  // Padding & Margin (Uses SpaceTokens)
  p?: ResponsiveProp<SpaceToken>; px?: ResponsiveProp<SpaceToken>; py?: ResponsiveProp<SpaceToken>
  pt?: ResponsiveProp<SpaceToken>; pb?: ResponsiveProp<SpaceToken>; pl?: ResponsiveProp<SpaceToken>; pr?: ResponsiveProp<SpaceToken>
  m?: ResponsiveProp<SpaceToken>; mx?: ResponsiveProp<SpaceToken>; my?: ResponsiveProp<SpaceToken>
  mt?: ResponsiveProp<SpaceToken>; mb?: ResponsiveProp<SpaceToken>; ml?: ResponsiveProp<SpaceToken>; mr?: ResponsiveProp<SpaceToken>

  // Custom Size & Positioning (Responsive CSS strings/numbers)
  width?: ResponsiveProp<string>; height?: ResponsiveProp<string>
  minWidth?: ResponsiveProp<string>; maxWidth?: ResponsiveProp<string>
  minHeight?: ResponsiveProp<string>; maxHeight?: ResponsiveProp<string>
  inset?: ResponsiveProp<string>; top?: ResponsiveProp<string>; bottom?: ResponsiveProp<string>
  left?: ResponsiveProp<string>; right?: ResponsiveProp<string>; zIndex?: ResponsiveProp<string>

Warning

top, right, bottom, left, and inset accept raw CSS strings (e.g. "0.5rem", "8px", "50%"), not SpaceToken values like sm, md, lg.
Spacing tokens only work with padding (p, px, py, pt, pr, pb, pl) and margin (m, mx, my, mt, mr, mb, ml) props.
❌ top="sm" — will not resolve
✅ top="0.5rem" — correct

// Border Radius (Uses RadiusTokens) r?: ResponsiveProp // All corners rtl?: ResponsiveProp // Top Left rtr?: ResponsiveProp // Top Right rbl?: ResponsiveProp // Bottom Left rbr?: ResponsiveProp // Bottom Right }

#### Example:
```tsx
<Box
  as="section"
  bg={{ base: 'bg-50', dark: 'bg-950' }}
  p="lg"
  r="xl"
  shadow
  width={{ base: '100%', md: '50rem' }}
>
  Box Content
</Box>

---

B. Flex

Implements a flexbox container. Renders a flex layout by default.

interface FlexOwnProps extends BoxOwnProps {
  display?: ResponsiveProp<'none' | 'flex' | 'inline-flex'>
  direction?: ResponsiveProp<
    'row' | 'column' | 'row-reverse' | 'column-reverse'
  >
  align?: ResponsiveProp<'stretch' | 'center' | 'start' | 'end' | 'baseline'>
  justify?: ResponsiveProp<
    'start' | 'center' | 'between' | 'around' | 'evenly' | 'end'
  >
  wrap?: ResponsiveProp<'nowrap' | 'wrap' | 'wrap-reverse'>
  centered?: boolean // Shortcut to center children perfectly on both axes
  gap?: ResponsiveProp<SpaceToken>
  gapX?: ResponsiveProp<SpaceToken>
  gapY?: ResponsiveProp<SpaceToken>
}

Example: Responsive Navbar

<Flex
  align="center"
  direction={{ base: 'column', sm: 'row' }}
  justify="between"
  p="md"
  gap="sm"
>
  <Text weight="bold">Logo</Text>
  <Flex gap="md">
    <Text>Home</Text>
    <Text>About</Text>
  </Flex>
</Flex>

---

C. Grid

Implements a CSS grid container with specialized normalization utilities.

interface GridOwnProps extends BoxOwnProps {
  display?: ResponsiveProp<'none' | 'grid' | 'inline-grid'>
  templateCols?: ResponsiveProp<number | string> // Numbers auto-resolve to 'repeat(N, 1fr)'
  templateRows?: ResponsiveProp<number | string>
  flow?: ResponsiveProp<
    'row' | 'column' | 'dense' | 'row dense' | 'column dense'
  >
  align?: ResponsiveProp<'stretch' | 'center' | 'start' | 'end' | 'baseline'>
  justify?: ResponsiveProp<'start' | 'center' | 'end' | 'between'>
  gap?: ResponsiveProp<SpaceToken>
  gapX?: ResponsiveProp<SpaceToken>
  gapY?: ResponsiveProp<SpaceToken>
}

Grid Item Options (Passed to children inside any Primitive):

Grid children can utilize custom positioning properties which auto-resolve:

• gridColumnSpan (e.g., 2 resolves to span 2)
• gridRowSpan (e.g., 3 resolves to span 3)
• gridArea

Example: Responsive 3-Column Card Layout

<Grid templateCols={{ base: 1, md: 3 }} gap="lg" width="100%">
  <Box bg="bg-200" p="md">
    Card 1
  </Box>
  <Box bg="bg-200" p="md" gridColumnSpan={{ base: 1, md: 2 }}>
    Card 2 (Spans 2 columns on desktops)
  </Box>
  <Box bg="bg-200" p="md">
    Card 3
  </Box>
</Grid>

---

D. Stack

A highly optimized, pre-configured Flex container intended for vertical lists. It overrides default flex directions to column and sets default width/sizing constraints.

// Stack Definition
export function Stack<T extends ElementType = 'div'>(props: FlexProps<T>) {
  return (
    <Flex direction="column" gap="sm" minWidth="0" width="100%" {...props} />
  )
}

Example:

For listing content, Stack's default gap="sm" is usually sufficient — no need to explicitly set gap:

<Stack>
  <Text>Item 1</Text>
  <Text>Item 2</Text>
  <Text>Item 3</Text>
</Stack>

Override gap only when you need more or less spacing than the default:

<Stack gap="md">
  <Text size="lg">Form Title</Text>
  <TextInput placeholder="Enter text..." ... />
  <Button>Submit</Button>
</Stack>

---

E. Text

The absolute engine for typography. Renders a span by default. It manages clipping, white-space constraints, tracking, and leading.

interface TextOwnProps {
  size?: ResponsiveProp<TextSize> // xs to 9xl
  color?: ThemeConditionProp<ColorValue>
  bg?: ThemeConditionProp<ColorValue>
  weight?: ResponsiveProp<FontWeight> // normal, medium, semibold, bold
  align?: ResponsiveProp<'left' | 'center' | 'right'>
  decoration?: ResponsiveProp<'underline' | 'line-through' | 'none'>
  transform?: ResponsiveProp<'uppercase' | 'lowercase' | 'capitalize' | 'none'>
  wrap?: ResponsiveProp<'wrap' | 'nowrap' | 'pretty' | 'balance'>
  whiteSpace?: ResponsiveProp<
    'normal' | 'nowrap' | 'pre' | 'pre-line' | 'pre-wrap'
  >
  truncate?: boolean // Ellipsis clipping on a single line
  lineClamp?: number // Standard multi-line truncation
  tracking?: ResponsiveProp<
    'tighter' | 'tight' | 'normal' | 'wide' | 'wider' | 'widest'
  >
  leading?: ResponsiveProp<
    'none' | 'tight' | 'snug' | 'normal' | 'relaxed' | 'loose'
  >
}

Example: Headline and Subtitle

Text also accepts all spacing props (mt, mb, py, px, etc.) and style directly — no wrapping Box needed.

<Stack gap="xs">
  <Text as="h1" size="3xl" weight="bold" leading="tight" tracking="tight">
    Create Account
  </Text>
  <Text color="muted" size="base">
    Welcome back to LifeForge.
  </Text>
</Stack>

<Text as="p" mt="md" py="sm" style={{ fontFamily: 'Inter' }}>
  Direct spacing and style — no Box wrapper.
</Text>

---

F. Icon

Wraps @iconify/react into a text-compatible block. Inherits the text color of the parent container by default and maps custom sizes seamlessly.

type IconProps = Omit<TextProps, 'size'> & {
  icon: string // e.g. "tabler:pencil", "tabler:hammer"
  size?: ResponsiveProp<string | number> // Defaults to '1.25em'
}

Example:

<Flex align="center" gap="sm">
  <Icon color="primary" icon="tabler:settings" size="1.5em" />
  <Text>Settings</Text>
</Flex>

---

G. Bordered

A primitive specifically made to draw layout borders without writing custom CSS borders.

interface BorderedOwnProps extends BoxOwnProps {
  borderColor?: ThemeConditionProp<ColorValue> // Defaults to base: 'bg-300', dark: 'bg-600'
  borderStyle?: 'solid' | 'dashed' | 'dotted' | 'double' | 'none'
  borderSide?: 'all' | 'top' | 'right' | 'bottom' | 'left' | 'x' | 'y'
  borderWidth?: string // Defaults to '1px'
}

Example: Side Border Sidebar

<Bordered
  borderSide="right"
  borderColor={{ base: 'bg-200', dark: 'bg-800' }}
  borderWidth="2px"
  height="100vh"
  width="16rem"
>
  Sidebar content
</Bordered>

---

H. Ring

Renders an interactive outline (focus rings, custom borders) mapping dynamically to states. Ideal for input focus effects.

interface RingProps extends BoxOwnProps {
  ringWidth?: ResponsiveProp<string> // Defaults to '3px'
  ringColor?: ThemeConditionProp<ColorValue> // Defaults to 'custom-500'
  ringOffsetWidth?: ResponsiveProp<string> // Defaults to '0px'
}

Example:

<Ring ringWidth="2px" ringColor="primary" r="md">
  <button>Clickable Element</button>
</Ring>

---

I. WithDivide

An extremely clever composition primitive that adds borders between adjacent sibling nodes. It avoids needing border-bottom logic on item render lists.

interface WithDivideProps {
  axis?: 'x' | 'y' // 'y' divides vertically (adds borderTop)
  // 'x' divides horizontally (adds borderLeft)
  color?: ThemeConditionProp<ColorValue> // Defaults to base: bg-200, dark: bg-700
  children?: ReactNode
}

Example: List Group Dividers

<WithDivide axis="y" color={{ base: 'bg-300', dark: 'bg-800' }}>
  <Stack gap="none">
    <Box p="md">Item 1</Box>
    <Box p="md">Item 2</Box>
    <Box p="md">Item 3</Box>
  </Stack>
</WithDivide>

---

J. Transition

Applies CSS transitions to a wrapped component utilizing the asChild composition pattern. No wrapper elements are injected into the DOM.

interface TransitionProps {
  duration?: number | string // e.g. 200, '300ms', '0.2s'. Defaults to '100ms'
  easing?:
    | 'linear'
    | 'ease'
    | 'ease-in'
    | 'ease-out'
    | 'ease-in-out'
    | (string & {})
  delay?: number | string
  property?:
    | PropertyValue
    | TransitionEntry
    | Array<PropertyValue | TransitionEntry>
}

Example: Smooth Color Change on Hover

<Transition duration="150ms" property={['background-color', 'color']}>
  <Box
    bg={{ base: 'bg-100', hover: 'primary' }}
    color={{ base: 'bg-950', hover: 'bg-50' }}
    p="md"
    r="md"
  >
    Hover Me
  </Box>
</Transition>

---

5. Composition & Chaining Rules

Primitives are designed to be composed together using the asChild pattern. This merges the class names, styling resolvers, and custom variables of multiple layers onto a single DOM node.

A. The asChild composition

When asChild is set, the primitive passes all of its compiled props and styles directly to its only child.

// ❌ INCORRECT: Injects redundant DOM elements, making styling hard to trace
<Transition>
  <Box bg="primary" p="md">
    <Text as="h3" size="lg">Headline</Text>
  </Box>
</Transition>

//     CORRECT: Flattens the hierarchy into a single clean DOM node
<Transition duration="200ms" property="all">
  <Box
    asChild
    bg={{ base: 'bg-100', hover: 'bg-200' }}
    p="md"
    r="md"
  >
    <Text as="h3" size="lg">Headline</Text>
  </Box>
</Transition>

B. Standard Layout Chain

When constructing standard layout components, follow this order:

1. Structural Grid/Stack: Define overall templates and spacing bounds.
2. Interactive/Animated Transition: Handle states and transition variables.
3. Card/Bordered Wrapper: Render the visible card backgrounds, shadows, and corners.
4. Content Flex/Stack: Lay out content alignment and gaps.

<Grid templateCols={{ base: 1, md: 3 }} gap="lg">
  {items.map(item => (
    <Transition key={item.id} duration="150ms" property="all">
      <Bordered asChild bg={{ base: 'bg-100', hover: 'bg-200' }} p="lg" r="lg">
        <Stack gap="md">
          <Text size="xl" weight="bold">
            {item.title}
          </Text>
          <Text color="muted">{item.desc}</Text>
        </Stack>
      </Bordered>
    </Transition>
  ))}
</Grid>

---

6. High-Level Forms & Interactive Components

A. Button

The core button component manages accessibility, internationalization translations, dynamic loading spinners, and personalization background-contrast matching.

type ButtonProps<T extends ElementType = 'button'> = ButtonOwnProps &
  FlexProps<T>

Category	Props
Button-specific	variant, dangerous, icon, iconPosition, loading, disabled, namespace
Inherited from Flex	All FlexProps — mt, width, position, top, gap, and everything from BoxProps (bg, p, r, shadow, etc.)

Since Button extends FlexProps (which extends BoxProps), any layout prop available on Flex or Box can be passed directly — no wrapping Box needed. Only reach for Box asChild when you need a prop that Flex/Box doesn't support (e.g. CSS properties only available via inline style).

Notable Engineering Features:

1. Dynamic Contrast Matching: In useButtonStyleProps, when variant="primary" is set, the button fetches the user's active theme color (derivedThemeColor) and runs getMostReadableColor() to compute a text color with optimal contrast.
2. Smart i18n Translation: If the children is a string, it automatically attempts to search for translations across various namespaces (e.g., buttons.cancel, common.buttons:cancel).
3. Loading Spinners: Renders the pre-animated svg-spinners:ring-resize icon automatically.

Example:

<Button
  variant="primary"
  icon="tabler:send"
  loading={isSubmitting}
  mt="lg" // Inherited from Flex — no Box wrapper needed
  width="100%" // Inherited from Flex
  onClick={onSubmit}
>
  sendFeedback
</Button>

---

B. Form Input Infrastructure (TextInput)

All inputs share a unified visual style by extending components from the inputs/shared module:

• InputWrapper: Creates the surrounding classic/plain background field, error display, and click handlers.
• InputLabel: Coordinates labels, required asterisks, and floating positions.
• InputIcon: Renders helper icons aligned within field paddings.

Example: Password Input with Visibility Toggles

<TextInput
  isPassword
  label="Password"
  placeholder="••••••••"
  value={password}
  icon="tabler:lock"
  errorMsg={errors.password}
  onChange={setPassword}
/>

---

7. Real-world Codebase Walkthrough

Here is a complete, real-world view page (UserCreationPage.tsx) utilizing the UI library. Observe how grid structures, text responsiveness, and inputs are combined without writing standard CSS or inline styles:

import { useMutation } from '@tanstack/react-query'
import { useState } from 'react'
import { useTranslation } from 'react-i18next'
import { toast } from 'react-toastify'

import { Button, Flex, Icon, Stack, Text, TextInput } from '@lifeforge/ui'

import forgeAPI from '@/forgeAPI'

function UserCreationPage() {
  const { t } = useTranslation('common.auth')

  const [formData, setFormData] = useState({
    email: '',
    username: '',
    name: '',
    password: '',
    confirmPassword: ''
  })

  const [errors, setErrors] = useState<Record<string, string>>({})

  const createUserMutation = useMutation(
    forgeAPI.user.auth.createFirstUser.mutationOptions({
      onSuccess: () => {
        toast.success(t('messages.userCreated'))
        window.location.reload()
      },
      onError: (error: Error) => {
        toast.error(error.message)
      }
    })
  )

  const updateField = (field: string) => (value: string) => {
    setFormData(prev => ({ ...prev, [field]: value }))
    setErrors(prev => ({ ...prev, [field]: '' }))
  }

  const validateForm = () => {
    const newErrors: Record<string, string> = {}

    if (!formData.email.trim()) {
      newErrors.email = t('validation.emailRequired')
    } else if (!/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(formData.email)) {
      newErrors.email = t('validation.emailInvalid')
    }

    if (!formData.username.trim()) {
      newErrors.username = t('validation.usernameRequired')
    }

    if (!formData.password) {
      newErrors.password = t('validation.passwordRequired')
    } else if (formData.password.length < 8) {
      newErrors.password = t('validation.passwordTooShort')
    }

    if (formData.password !== formData.confirmPassword) {
      newErrors.confirmPassword = t('validation.passwordMismatch')
    }

    setErrors(newErrors)
    return Object.keys(newErrors).length === 0
  }

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault()
    if (!validateForm()) return

    createUserMutation.mutateAsync({
      email: formData.email,
      username: formData.username,
      name: formData.name,
      password: formData.password
    })
  }

  return (
    // 1. Center layout with responsive paddings and full width bounds
    <Flex centered direction="column" px="xl" width="100%">
      // 2. Main title using asChild to combine structural Box with semantic
      Heading
      <Flex asChild centered gap="sm" mb="xl">
        <Text as="h1" size="3xl" weight="semibold" whiteSpace="nowrap">
          <Icon color="primary" icon="tabler:hammer" />
          <div>
            LifeForge
            <Text color="primary" size="4xl">
              .
            </Text>
          </div>
        </Text>
      </Flex>
      // 3. Responsive typography heading (scales automatically on
      tablet/desktop)
      <Text
        align="center"
        as="h2"
        size={{ base: '4xl', sm: '5xl' }}
        tracking="wide"
        weight="semibold"
      >
        {t('welcome.header')}
      </Text>
      // 4. Subtitle with themed color and responsive margins
      <Text
        align="center"
        as="p"
        color="muted"
        mt={{ base: 'sm', sm: 'md' }}
        size={{ base: 'base', sm: 'xl' }}
      >
        {t('welcome.desc')}
      </Text>
      // 5. Central form container bounded by max width
      <Stack maxWidth="40rem" mt="2xl" width="100%">
        <TextInput
          errorMsg={errors.email}
          icon="tabler:mail"
          inputMode="email"
          label={t('inputs.email.label')}
          placeholder={t('inputs.email.placeholder')}
          value={formData.email}
          onChange={updateField('email')}
        />
        <TextInput
          errorMsg={errors.username}
          icon="tabler:at"
          label={t('inputs.username.label')}
          placeholder={t('inputs.username.placeholder')}
          value={formData.username}
          onChange={updateField('username')}
        />
        <TextInput
          isPassword
          errorMsg={errors.password}
          icon="tabler:lock"
          label={t('inputs.password.label')}
          placeholder={t('inputs.password.placeholder')}
          value={formData.password}
          onChange={updateField('password')}
        />
        <TextInput
          isPassword
          errorMsg={errors.confirmPassword}
          icon="tabler:lock-check"
          label={t('inputs.confirmPassword.label')}
          placeholder={t('inputs.confirmPassword.placeholder')}
          value={formData.confirmPassword}
          onChange={updateField('confirmPassword')}
        />
        // 6. Action Button with custom icons, alignment, and loading states
        <Button
          icon="tabler:arrow-right"
          iconPosition="end"
          loading={createUserMutation.isPending}
          mt="md"
          onClick={handleSubmit}
        >
          {t('buttons.proceed')}
        </Button>
      </Stack>
    </Flex>
  )
}

export default UserCreationPage

---

---

8. Migration Guide: Legacy component-bg-* Utility Classes

The legacy component-bg-* utility classes have been removed from the codebase. These were Tailwind-based utilities defined in src/core/styles/themes/componentBG.css. Every one of them must be replaced with the corresponding bg prop on UI primitives (Box, Flex, Card, etc.).

Legacy → Modern Mapping

Legacy Class	Equivalent surface Preset
component-bg	surface.default
component-bg-with-hover	surface.defaultInteractive
component-bg-lighter	surface.light
component-bg-lighter-with-hover	surface.lightInteractive
darker-component-bg-with-hover	{ base: 'bg-200', dark: 'bg-800', hover: 'bg-200', darkHover: 'bg-800' } (no preset — inline if needed)

The legacy classes also had .has-bg-image & nested variants that applied backdrop-blur-xs and reduced opacity. In the new system, the .has-bg-image and .hasBgImage/.darkHasBgImage state keys on the bg prop handle this automatically — you do not need to manually apply backdrop or opacity.

Migration Pattern

Before (using removed Tailwind utilities):

<button className="component-bg-lighter-with-hover w-full rounded-lg p-6 text-left">
  <span className="font-medium">Item</span>
</button>

After (using UI primitives with surface preset):

import { Box, Text, surface } from '@lifeforge/ui'

;<Box as="button" bg={surface.lightInteractive} p="lg" r="lg" width="100%">
  <Text weight="medium">Item</Text>
</Box>

Most legacy classes map directly to a surface preset (see table above). Prefer using the preset over writing the object inline.

Selected/Active State Borders

Legacy code often combined component-bg-lighter-with-hover with Tailwind border utilities to indicate selection:

className = 'component-bg-lighter-with-hover border-2 border-custom-500'

Replace this with Card (which already handles interactive backgrounds and shadows), or use Box with bg state conditions directly:

<Card isInteractive r="lg">
  <Text weight="medium">Item</Text>
</Card>

The Card component with isInteractive applies the correct background mapping automatically:

bg={
  isInteractive
    ? { base: 'bg-50', dark: 'bg-900', hover: 'bg-100', darkHover: 'bg-800' }
    : { base: 'bg-50', dark: 'bg-900' }
}

If you need custom background shades, use Box directly:

<Box
  as="button"
  bg={{
    base: 'bg-100',
    dark: 'bg-800',
    hover: 'bg-200',
    darkHover: 'bg-700'
  }}
  p="lg"
  r="lg"
  width="100%"
>
  <Text weight="medium">Item</Text>
</Box>

For selected-state borders, use the Ring primitive to wrap the card instead of absolute-position hacks:

<Ring ringWidth="2px" ringColor="custom-500" r="lg">
  <Card isInteractive ...>
    ...
  </Card>
</Ring>

Note

Ring applies the outline to its child using outline, which does not affect layout — no absolute positioning needed.

Check Icon Overlay

When an item is selected, a check icon overlay can be placed with absolute positioning:

Before:

<Icon
  className="text-custom-500 absolute right-1.5 bottom-2 size-6"
  icon="tabler:check"
/>

After:

<Box position="absolute" bottom="sm" right="sm">
  <Icon color="custom-500" icon="tabler:check" size="1.5em" />
</Box>

Running a Migration

1. Search for component-bg in your component files.
2. Map each class to the bg prop using the table above.
3. Remove className entirely — use primitive props (p, py, r, width, etc.) for all layout.
4. Replace selected-state borders with Bordered overlay pattern.
5. Replace all text-custom-500, text-bg-500 etc. Tailwind color classes with the color prop on Text or Icon.

---

9. Migration Guide: @iconify/react → @lifeforge/ui Icon Primitive

The standalone Icon from @iconify/react must never be imported directly. Always use the Icon primitive exported by @lifeforge/ui.

Key Differences

Aspect	@iconify/react Icon	@lifeforge/ui Icon
Import	import { Icon } from '@iconify/react'	import { Icon } from '@lifeforge/ui'
Sizing	width / height props (e.g. width="1.5em")	size prop (e.g. size="1.5em")
Color	className="text-custom-500" (Tailwind)	color="custom-500" (design token)
Layout	className="absolute right-1.5 bottom-2" (Tailwind)	Box asChild position="absolute" bottom="sm" right="sm"
Inherits	—	All Text props (ml, mr, display, truncate, etc.)

Icon is built on top of the Text primitive, so any prop that Text accepts (e.g. ml, mr, display, truncate, wrap, className, style) works directly on Icon without needing a Box wrapper.

Migration Pattern

Before:

import { Icon } from '@iconify/react'

;<Icon
  className="text-custom-500"
  icon="tabler:check"
  width="1.5em"
  height="1.5em"
/>

After (positioned):

import { Box, Icon } from '@lifeforge/ui'

;<Box asChild position="absolute" bottom="sm" right="sm">
  <Icon color="custom-500" icon="tabler:check" size="1.5em" />
</Box>

After (inline — no positioning needed):

import { Icon } from '@lifeforge/ui'

;<Icon color="custom-500" icon="tabler:check" />

Box asChild is only needed when the Icon needs layout props it doesn't inherit (position, top, left, etc.). For spacing (ml, mr) and display properties, pass them directly to Icon since it inherits all Text props.

Migration Checklist

1. Replace import { Icon } from '@iconify/react' with import { Icon } from '@lifeforge/ui' (or add Icon to the existing destructured import from @lifeforge/ui).
2. Replace width="..." height="..." with a single size="...".
3. Replace className="text-custom-500" / className="text-bg-500" with color="custom-500" / color="muted".
4. For positioned icons (position, top, right, bottom), wrap with Box asChild. For spacing and display, pass props directly to Icon (it inherits all Text props).
5. Remove all remaining className props from Icon — they are not used anywhere in the codebase.

---

10. Developer Quick-Reference Checklist

Before submitting a pull request, verify that you have adhered to all core design patterns:

• No Tailwind classes: There is not a single className="flex..." or similar Tailwind class in your components.
• No arbitrary inline styles: Inline style is only used for properties computed at runtime (e.g. coordinates or scales). Standard layouts use p, m, width, height, etc.
• Strict font-sizing rules: Prohibited text-xs is never used. Default size is text-base (omit size prop), and titles use sizes >= text-lg.
• Correct loaders: Form/button loading states use the pre-animated svg-spinners:ring-resize icon and never use custom animate-spin utilities.
• Type safety: Typescript any is never used. All prop overrides and custom handlers are explicitly typed.
• Datetime manipulation: Standard JavaScript Date is never used. day.js is imported for any date calculations.
• Component organization: Components are strictly separated into individual files under their respective components/ folders instead of being grouped together.
• Conventional functions: All React components use standard function declarations (export function Component()) and avoid arrow functions.