material-3 — Claude Code skill: Material Design 3 in Compose

---
name: material-3
description: >
  Implement Google's Material Design 3 (Material You) UI system. Primary: Jetpack Compose
  Material3 (MaterialTheme, components, adaptive layout). Also Flutter and limited web
  (@material/web, maintenance mode). Covers tokens, 30+ components, layout, theming,
  M3 Expressive (platform matrix), and accessibility. Use when: "material design", "MD3",
  "material you", "Jetpack Compose", "MaterialTheme", "material component", "md3 button".
user-invokable: true
argument-hint: "[component|theme|layout|scaffold|audit] [description or URL]"
---

# Material Design 3

This skill guides implementation of Google's Material Design 3 (MD3) — a personal, adaptive, expressive design system. MD3 uses dynamic color, tonal surfaces, rounded shapes, and spring-based motion to create UIs that feel alive and personal.

## Philosophy

MD3 is built on three principles:
- **Personal**: Dynamic color adapts UI to the user's wallpaper or content. Theming is individual, not one-size-fits-all.
- **Adaptive**: Layouts transform across 5 window size classes. Components resize, reposition, and change form factor responsively.
- **Expressive**: Shape morphing, spring physics, and emphasized typography create moments of delight without sacrificing usability.

## Current Updates: Google I/O 2026

Material's [Google I/O 2026 update](https://m3.material.io/blog/whats-new-at-io26) reinforces a **Compose-first** Android path and expands expressive/adaptive guidance:

- **Material Android is Compose-first**: For new Android work, prefer Jetpack Compose Material3 for the latest components, expressive APIs, adaptive scaffolds, and Styles API integration. Android Views may remain necessary in existing apps, but they should not be treated as the default path for new Material 3 implementations.
- **Expressive layout system**: Use an expressive layout scaffold to adapt screens across mobile, desktop, foldables, watches, XR, and other spatial form factors. Start from adaptive scaffolds/window size classes instead of fixed phone-first layouts.
- **8dp spacing system**: Apply spacing tokens for margins, padding, and gaps so layouts and components can adapt programmatically to device type and density.
- **New/updated expressive components**: Lists, menus, search, and search app bars have refreshed expressive guidance, with Jetpack Compose as the primary implementation target.
- **Watches and XR**: Watches emphasize physics-based motion, arc text, and edge-hugging containers. XR emphasizes spatial panels and depth-based elevation.

**Key differences from MD2:**
- Tonal surfaces replace elevation shadows as the primary depth cue
- Dynamic color generates full schemes from a single seed color
- Fully rounded corners by default (not slightly rounded)
- Spring-based motion physics replace fixed easing curves for components
- 3 levels of user-controlled contrast (standard/medium/high)

**Relationship with frontend-design skill:**
When both skills are active, MD3 provides the design system (tokens, components, layout rules) and frontend-design provides creative direction within those constraints. MD3 rules take precedence for component structure and token usage. Note: Roboto/Roboto Flex IS the correct default typeface in MD3 — the frontend-design guidance to avoid Roboto does not apply when implementing MD3.

## Decision Tree

**What are you building?**
```
Full app scaffold        → See "Common Patterns: App Shell" + references/layout-and-responsive.md
Single component         → See "Component Quick Reference" table → references/component-catalog.md
Custom theme             → See references/theming-and-dynamic-color.md
Form / input layout      → See references/component-catalog.md § Input Components
Navigation structure     → See references/navigation-patterns.md
Data display             → See references/component-catalog.md § Data Display
```

**What platform?**
```
Jetpack Compose          → Primary: androidx.compose.material3, MaterialTheme, references/*
Flutter                  → useMaterial3: true in ThemeData, ColorScheme.fromSeed()
Web (vanilla JS)         → @material/web (limited; maintenance mode) + CSS custom properties
Web (React/Vue/Svelte)   → CSS custom properties + wrapper components (no official React lib)
Web (CSS-only)           → MD3 token values as CSS custom properties (no <md-*> elements)
```

## Design Token System

All MD3 tokens use the `md.sys` namespace. **Jetpack Compose** maps roles to `MaterialTheme.colorScheme`, `MaterialTheme.typography`, and `MaterialTheme.shapes` (same semantic roles as the spec). **On the web**, these map to CSS custom properties (`--md-sys-*`):

### Color Tokens (`--md-sys-color-*`)
| Token | Purpose |
|-------|---------|
| `primary` | High-emphasis fills, text, icons against surface |
| `on-primary` | Text/icons on primary |
| `primary-container` | Standout fill for key components (FAB, etc.) |
| `on-primary-container` | Text/icons on primary-container |
| `secondary` / `on-secondary` | Less prominent accents |
| `secondary-container` / `on-secondary-container` | Recessive components (tonal buttons) |
| `tertiary` / `on-tertiary` | Contrasting accents |
| `tertiary-container` / `on-tertiary-container` | Complementary containers |
| `error` / `on-error` | Error states (static — doesn't change with dynamic color) |
| `error-container` / `on-error-container` | Error container fills |
| `surface` | Default background |
| `on-surface` | Text/icons on any surface |
| `on-surface-variant` | Lower-emphasis text/icons on surface |
| `surface-container-lowest` | Lowest-emphasis container |
| `surface-container-low` | Low-emphasis container |
| `surface-container` | Default container (nav areas) |
| `surface-container-high` | High-emphasis container |
| `surface-container-highest` | Highest-emphasis container |
| `surface-dim` / `surface-bright` | Maintain relative brightness across light/dark |
| `inverse-surface` / `inverse-on-surface` / `inverse-primary` | Contrasting elements (snackbars) |
| `outline` | Important boundaries (text field borders) |
| `outline-variant` | Decorative elements (dividers) |

Full details: `references/color-system.md`

### Typography Tokens (`--md-sys-typescale-*`)
| Scale | Sizes | Use |
|-------|-------|-----|
| Display | L / M / S | Hero text, large numbers |
| Headline | L / M / S | Section headers |
| Title | L / M / S | Smaller headers, card titles |
| Body | L / M / S | Paragraph text, descriptions |
| Label | L / M / S | Buttons, chips, captions |

Each style has tokens for: `-font`, `-weight`, `-size`, `-line-height`, `-tracking`
Plus 15 **emphasized** variants (higher weight) via `--md-sys-typescale-emphasized-*`

Full details: `references/typography-and-shape.md`

### Shape Tokens (`--md-sys-shape-corner-*`)
| Token | Value | Example components |
|-------|-------|-------------------|
| `none` | 0dp | — |
| `extra-small` | 4dp | Chips, snackbars |
| `small` | 8dp | Text fields, menus |
| `medium` | 12dp | Cards |
| `large` | 16dp | FABs, navigation drawer |
| `large-increased` | 20dp | (Expressive) |
| `extra-large` | 28dp | Dialogs, bottom sheets |
| `extra-large-increased` | 32dp | (Expressive) |
| `extra-extra-large` | 48dp | (Expressive) |
| `full` | 9999px | Buttons, chips, badges |

### Elevation Levels
| Level | DP | Tonal offset | Use |
|-------|-----|-------------|-----|
| 0 | 0dp | None | Flat surfaces, most components at rest |
| 1 | 1dp | +5% primary | Elevated cards, modal sheets |
| 2 | 3dp | +8% primary | Menus, nav bar, scrolled app bar |
| 3 | 6dp | +11% primary | FAB, dialogs, search, date/time pickers |
| 4 | 8dp | +12% primary | (hover/focus increase only) |
| 5 | 12dp | +14% primary | (hover/focus increase only) |

Elevation in MD3 is communicated through **tonal surface color**, not shadows. Shadows are only used when needed for additional protection against busy backgrounds.

### Motion
MD3 Expressive (May 2025) introduced **spring-based motion physics** for components. The legacy easing/duration system is still used for **transitions** (enter/exit/shared-axis):

| Easing | Duration | Transition type |
|--------|----------|-----------------|
| Emphasized | 500ms | Begin and end on screen |
| Emphasized decelerate | 400ms | Enter the screen |
| Emphasized accelerate | 200ms | Exit the screen |
| Standard | 300ms | Begin and end on screen (utility) |
| Standard decelerate | 250ms | Enter screen (utility) |
| Standard accelerate | 200ms | Exit screen (utility) |

CSS easing values:
- Emphasized: `cubic-bezier(0.2, 0, 0, 1)`
- Emphasized decelerate: `cubic-bezier(0.05, 0.7, 0.1, 1)`
- Emphasized accelerate: `cubic-bezier(0.3, 0, 0.8, 0.15)`
- Standard: `cubic-bezier(0.2, 0, 0, 1)`
- Standard decelerate: `cubic-bezier(0, 0, 0, 1)`
- Standard accelerate: `cubic-bezier(0.3, 0, 1, 1)`

## Component Quick Reference

| Component | Web Element | Key Variants | Category |
|-----------|------------|--------------|----------|
| Button | `md-filled-button`, `md-outlined-button`, `md-text-button`, `md-elevated-button`, `md-filled-tonal-button` | Filled, Outlined, Text, Elevated, Tonal; 5 sizes (XS–XL); toggle | Actions |
| Button group | `md-button-group` | Standard, connected | Actions |
| Extended FAB | `md-extended-fab` | Surface, Primary, Secondary, Tertiary | Actions |
| FAB | `md-fab` | Small, Medium, Large | Actions |
| FAB menu | — | — | Actions |
| Icon button | `md-icon-button`, `md-filled-icon-button`, `md-filled-tonal-icon-button`, `md-outlined-icon-button` | Standard, Filled, Filled Tonal, Outlined | Actions |
| Segmented button | — | Single-select, Multi-select | Actions |
| Split button | — | — | Actions |
| Badge | — | Small (dot), Large (count) | Communication |
| Loading indicator | — | Linear, Circular | Communication |
| Progress indicator | `md-linear-progress`, `md-circular-progress` | Linear, Circular; determinate/indeterminate | Communication |
| Snackbar | — | Single-line, Two-line, Action | Communication |
| Tooltip | — | Plain, Rich | Communication |
| Card | — | Filled, Outlined, Elevated | Containment |
| Carousel | — | Multi-browse, Uncontained, Hero | Containment |
| Dialog | `md-dialog` | Basic, Full-screen | Containment |
| Bottom sheet | — | Standard, Modal | Sheets |
| Side sheet | — | Standard, Modal | Sheets |
| Divider | `md-divider` | Full-width, Inset | Containment |
| Checkbox | `md-checkbox` | — | Input |
| Chips | `md-chip-set`, `md-assist-chip`, `md-filter-chip`, `md-input-chip`, `md-suggestion-chip` | Assist, Filter, Input, Suggestion | Input |
| Date picker | — | Docked, Modal, Range | Input |
| Menu | `md-menu`, `md-menu-item` | — | Input |
| Radio button | `md-radio` | — | Input |
| Slider | `md-slider` | Continuous, Discrete, Range | Input |
| Switch | `md-switch` | With/without icon | Input |
| Text field | `md-filled-text-field`, `md-outlined-text-field` | Filled, Outlined | Input |
| Time picker | — | Docked, Modal | Input |
| App bar (top) | — | Center-aligned, Small, Medium, Large | Navigation |
| Navigation bar | `md-navigation-bar` | — | Navigation |
| Navigation drawer | `md-navigation-drawer` | Standard, Modal | Navigation |
| Navigation rail | — | — | Navigation |
| Search | — | Search bar, Search view | Navigation |
| Tabs | `md-tabs`, `md-primary-tab`, `md-secondary-tab` | Primary, Secondary | Navigation |
| Toolbar | — | — | Navigation |
| List | `md-list`, `md-list-item` | One-line, Two-line, Three-line | Data Display |

**Note:** Components marked with `—` for web element don't have @material/web implementations yet. Use CSS custom properties with standard HTML for these. **Compose** mappings and examples live in `references/component-catalog.md`.

Full component details with code examples: `references/component-catalog.md`

## Jetpack Compose (primary)

Use **`androidx.compose.material3`** with `MaterialTheme` and Material 3 composables (`Scaffold`, `Button`, `NavigationBar`, top app bars, etc.).

- **Theming**: `MaterialTheme(colorScheme = …, typography = …, shapes = …)`. Prefer `dynamicLightColorScheme` / `dynamicDarkColorScheme` on **Android 12+ (API 31+)** when dynamic color is desired; otherwise `lightColorScheme` / `darkColorScheme` or generated theme code from Material Theme Builder.
- **Adaptive UI**: Window size classes, list-detail and supporting-pane layouts, foldables — see `references/layout-and-responsive.md` and `references/navigation-patterns.md`.
- **Edge-to-edge & insets**: Lay out content with `WindowInsets` / scaffold padding so bars and IME behave correctly — see `references/layout-and-responsive.md`.
- **Experimental APIs**: Some Material 3 APIs require `@OptIn(ExperimentalMaterial3Api::class)` or expressive opt-ins; match your BOM and compiler.

```kotlin
MaterialTheme(
    colorScheme = colorScheme, // from dynamicLightColorScheme / lightColorScheme / etc.
    typography = Typography(),
    shapes = Shapes(),
) {
    // M3 content — prefer references for Scaffold, navigation, text fields
}
```

## Web (limited): @material/web

**Important:** Per [Material Design 3 for Web](https://m3.material.io/develop/web), **Material Web Components are in maintenance mode** and **M3 Expressive is not implemented on Web**. Use `@material/web` for token-backed web UIs when appropriate, but do not treat it as equivalent to Compose for current Expressive features.

### Setup

```bash
npm install @material/web
```

### Import Components Individually

Always import only the components you use — importing the entire package bloats the bundle:

```javascript
// Good — individual imports
import '@material/web/button/filled-button.js';
import '@material/web/button/outlined-button.js';
import '@material/web/textfield/outlined-text-field.js';
import '@material/web/icon/icon.js';

// Bad — never do this
import '@material/web'; // imports everything
```

### Basic Usage

```html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <link href="https://fonts.googleapis.com/css2?family=Roboto+Flex:wght@400;500;700&display=swap" rel="stylesheet">
  <link href="https://fonts.googleapis.com/icon?family=Material+Symbols+Outlined" rel="stylesheet">
</head>
<body>
  <md-filled-button>Get started</md-filled-button>
  <md-outlined-text-field label="Email" type="email"></md-outlined-text-field>

  <script type="module">
    import '@material/web/button/filled-button.js';
    import '@material/web/textfield/outlined-text-field.js';
  </script>
</body>
</html>
```

### Theming with CSS Custom Properties

Apply a custom theme by setting CSS custom properties on `:root` or any ancestor:

```css
:root {
  /* Color scheme (generate with @material/material-color-utilities) */
  --md-sys-color-primary: #6750A4;
  --md-sys-color-on-primary: #FFFFFF;
  --md-sys-color-primary-container: #EADDFF;
  --md-sys-color-on-primary-container: #21005D;
  --md-sys-color-secondary: #625B71;
  --md-sys-color-on-secondary: #FFFFFF;
  --md-sys-color-secondary-container: #E8DEF8;
  --md-sys-color-on-secondary-container: #1D192B;
  --md-sys-color-surface: #FEF7FF;
  --md-sys-color-on-surface: #1D1B20;
  --md-sys-color-surface-container: #F3EDF7;
  --md-sys-color-outline: #79747E;
  --md-sys-color-outline-variant: #CAC4D0;

  /* Typography */
  --md-sys-typescale-body-large-font: 'Roboto Flex', sans-serif;
  --md-sys-typescale-body-large-size: 1rem;
  --md-sys-typescale-body-large-weight: 400;
  --md-sys-typescale-body-large-line-height: 1.5rem;

  /* Shape */
  --md-sys-shape-corner-full: 9999px;
  --md-sys-shape-corner-medium: 12px;
}
```

### Component-Level Overrides

Override individual component tokens for specific customization:

```css
md-filled-button {
  --md-filled-button-container-color: var(--md-sys-color-primary);
  --md-filled-button-label-text-color: var(--md-sys-color-on-primary);
  --md-filled-button-container-shape: var(--md-sys-shape-corner-full);
  --md-filled-button-container-height: 40px;
}

md-outlined-text-field {
  --md-outlined-text-field-container-shape: var(--md-sys-shape-corner-small);
  --md-outlined-text-field-focus-outline-color: var(--md-sys-color-primary);
}
```

### Dark Theme

Apply dark theme by overriding color tokens on a class or media query:

```css
@media (prefers-color-scheme: dark) {
  :root {
    --md-sys-color-primary: #D0BCFF;
    --md-sys-color-on-primary: #381E72;
    --md-sys-color-primary-container: #4F378B;
    --md-sys-color-on-primary-container: #EADDFF;
    --md-sys-color-surface: #141218;
    --md-sys-color-on-surface: #E6E0E9;
    --md-sys-color-surface-container: #211F26;
    --md-sys-color-outline: #938F99;
    --md-sys-color-outline-variant: #49454F;
  }
}
```

Full theming guide: `references/theming-and-dynamic-color.md`

## Common Patterns

### App Shell

Standard MD3 app with responsive navigation + top app bar + content area:

```html
<div class="md3-app">
  <nav class="md3-nav-rail" aria-label="Main navigation">
    <!-- Navigation rail for medium+ screens -->
    <md-fab size="small" aria-label="Compose">
      <md-icon slot="icon">edit</md-icon>
    </md-fab>
    <md-navigation-bar>
      <md-navigation-tab label="Home">
        <md-icon slot="active-icon">home</md-icon>
        <md-icon slot="inactive-icon">home</md-icon>
      </md-navigation-tab>
      <md-navigation-tab label="Search">
        <md-icon slot="active-icon">search</md-icon>
        <md-icon slot="inactive-icon">search</md-icon>
      </md-navigation-tab>
    </md-navigation-bar>
  </nav>
  <main class="md3-content">
    <header class="md3-top-app-bar">
      <h1 class="md3-top-app-bar__title" style="font: var(--md-sys-typescale-title-large)">
        Page Title
      </h1>
    </header>
    <div class="md3-body">
      <!-- Content here -->
    </div>
  </main>
</div>
```

```css
.md3-app {
  display: flex;
  min-height: 100vh;
  background: var(--md-sys-color-surface);
  color: var(--md-sys-color-on-surface);
}

.md3-nav-rail {
  width: 80px;
  background: var(--md-sys-color-surface);
  border-right: 1px solid var(--md-sys-color-outline-variant);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding-top: 12px;
  gap: 12px;
}

.md3-content {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.md3-top-app-bar {
  height: 64px;
  padding: 0 16px;
  display: flex;
  align-items: center;
  background: var(--md-sys-color-surface);
}

.md3-body {
  padding: 24px;
  flex: 1;
}

/* Responsive: switch to bottom nav on compact */
@media (max-width: 599px) {
  .md3-app { flex-direction: column; }
  .md3-nav-rail {
    order: 1;
    width: 100%;
    flex-direction: row;
    justify-content: center;
    border-right: none;
    border-top: 1px solid var(--md-sys-color-outline-variant);
    padding: 0;
  }
}
```

### Card Grid

```html
<div class="md3-card-grid">
  <div class="md3-card md3-card--outlined">
    <img src="image.jpg" alt="Description" class="md3-card__media">
    <div class="md3-card__content">
      <h3 style="font: var(--md-sys-typescale-title-medium)">Card Title</h3>
      <p style="font: var(--md-sys-typescale-body-medium); color: var(--md-sys-color-on-surface-variant)">
        Supporting text for this card.
      </p>
    </div>
    <div class="md3-card__actions">
      <md-text-button>Learn more</md-text-button>
      <md-filled-tonal-button>Action</md-filled-tonal-button>
    </div>
  </div>
</div>
```

```css
.md3-card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}

.md3-card--outlined {
  border: 1px solid var(--md-sys-color-outline-variant);
  border-radius: var(--md-sys-shape-corner-medium, 12px);
  background: var(--md-sys-color-surface);
  overflow: hidden;
}

.md3-card__content { padding: 16px; }
.md3-card__actions { padding: 8px 16px 16px; display: flex; gap: 8px; justify-content: flex-end; }
.md3-card__media { width: 100%; aspect-ratio: 16/9; object-fit: cover; }
```

### Form Layout

```html
<form class="md3-form">
  <md-outlined-text-field label="Full name" required></md-outlined-text-field>
  <md-outlined-text-field label="Email" type="email" required></md-outlined-text-field>
  <md-outlined-text-field label="Message" type="textarea" rows="4"></md-outlined-text-field>
  <div class="md3-form__actions">
    <md-text-button type="reset">Cancel</md-text-button>
    <md-filled-button type="submit">Submit</md-filled-button>
  </div>
</form>
```

```css
.md3-form {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 560px;
}

.md3-form__actions {
  display: flex;
  gap: 8px;
  justify-content: flex-end;
  margin-top: 8px;
}
```

More patterns: `references/navigation-patterns.md`, `references/layout-and-responsive.md`

## Anti-Patterns

**Never do these when implementing MD3:**

- **Mix MD2 and MD3 libraries**: Don't use `@material/mdc-*` (MD2) alongside `@material/web` (MD3). They have incompatible APIs and styling.
- **Hardcode colors**: Always use `var(--md-sys-color-*)` tokens, never raw hex/rgb values. Hardcoded colors break dynamic theming, dark mode, and contrast adjustment.
- **Ignore tonal pairing**: Only combine colors in their intended pairs (e.g., `primary` + `on-primary`, `surface-container` + `on-surface`). Arbitrary pairings break contrast in dynamic color and high contrast modes.
- **Use `outline` for dividers**: Use `outline-variant` for dividers. `outline` is for important boundaries like text field borders.
- **Import all of @material/web**: Always import individual component modules. Barrel imports include every component and destroy bundle size.
- **Use `border-radius` directly**: Use shape tokens (`var(--md-sys-shape-corner-medium)`) so shapes stay consistent with theming.
- **Use shadows for elevation by default**: MD3 communicates elevation through tonal surface color, not shadows. Only add shadows when elements need extra separation from busy backgrounds.
- **Apply frontend-design "avoid Roboto" rule**: On **Android**, **Roboto** is the default Material typeface; **web** often uses Roboto or Roboto Flex with MD3 tokens. Replace only when intentionally customizing the type scale.
- **Assume SSR compatibility**: `@material/web` uses Web Components (custom elements) which require JavaScript to render. They won't produce meaningful HTML in SSR without additional hydration strategies.
- **Ignore foldables and large screens**: MD3 is designed for all screen sizes. Don't ship phone-only layouts — use canonical layouts, multi-pane at 600dp+, and test on foldable/tablet emulators. Place no interactive content across the fold/hinge.
- **Stretch content to fill wide screens**: On Large (1200dp+) and Extra-large (1600dp+) windows, constrain content to a max width (840–1040dp). Endless-width text lines are unreadable.

## Platform Notes

### Flutter
```dart
MaterialApp(
  theme: ThemeData(
    useMaterial3: true,
    colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
  ),
);
```

### Jetpack Compose
See **[Jetpack Compose (primary)](#jetpack-compose-primary)** above. Use `LocalContext.current` with `dynamicLightColorScheme` / `dynamicDarkColorScheme` only when `Build.VERSION.SDK_INT >= Build.VERSION_CODES.S` and dynamic color is enabled; otherwise supply static light/dark schemes.

### Component Name Mapping
| Concept | Web | Flutter | Compose |
|---------|-----|---------|---------|
| Filled button | `md-filled-button` | `FilledButton` | `Button` |
| Outlined text field | `md-outlined-text-field` | `OutlinedTextField` | `OutlinedTextField` |
| FAB | `md-fab` | `FloatingActionButton` | `FloatingActionButton` |
| Navigation bar | `md-navigation-bar` | `NavigationBar` | `NavigationBar` |
| Switch | `md-switch` | `Switch` | `Switch` |

## M3 Expressive (May 2025)

The Expressive update adds visual richness while maintaining usability. **Availability differs by platform** — do not assume one stack implements everything.

| Capability | Jetpack Compose | Flutter | Web (`@material/web`) |
|------------|-----------------|---------|------------------------|
| Expressive layout scaffold / adaptive layout | Compose-first via Material3 adaptive APIs and window size classes | Use Flutter adaptive/layout primitives | CSS/container queries/manual layout; no Material Web parity |
| 8dp spacing system | Use design tokens / `Dp` spacing constants; keep margins, padding, and gaps adaptive | Use theme spacing constants | CSS custom properties / design tokens |
| Expressive lists, menus, search, search app bar | Primary target per current Material guidance; check BOM and opt-ins | Check current Flutter Material docs | Spec-aligned custom implementation; `@material/web` is maintenance-only |
| Spring / motion physics | Supported in Material 3 (see `MotionScheme`, expressive APIs per BOM) | Varies by Flutter Material version | **Not** in Material Web; use easing/duration or custom motion |
| Emphasized typography | Via theme / type scale | Via theme | Token/CSS only; no full Expressive component set |
| Shape morphing | Compose-first in Google’s expressive rollout | Check current Flutter docs | **Not** in `@material/web` |
| New button sizes (XS–XL), toggle | Follow Compose Material3 components | Follow Flutter MD3 | Height/CSS approximations only |
| Extra corner tokens (e.g. large-increased) | `MaterialTheme.shapes` / tokens | Theme shapes | CSS `--md-sys-shape-*` |
| 3 contrast levels | Scheme builders / system | Plugins / manual | `SchemeContent` contrast parameter in JS utilities |
| Watches / XR form factors | Use Compose/Wear/XR-specific guidance where available | Platform-specific | Web/spatial UI custom implementation |

**Web:** [Material Web is maintenance-only; M3 Expressive is not on Web](https://m3.material.io/develop/web). Use CSS easing/duration tokens as fallback for motion, not spring parity.

**Legacy easing/duration** remains valid for **transitions** (enter/exit/shared-axis) where the spec still references them; see the Motion table below.

## MD3 Compliance Audit

When invoked with `audit` as the argument (e.g., `/material-3 audit`), or when asked to audit/review MD3 compliance, analyze the target app or page and produce a compliance report.

### Audit Procedure

1. **Identify the target**: The user provides a URL (use browser tools to inspect), file paths (read source), or a running app.
2. **Inspect the following categories** and score each 0–10:

| Category | What to check |
|----------|--------------|
| **Color tokens** | **Web:** `--md-sys-color-*` / generated CSS. **Compose:** `MaterialTheme.colorScheme` roles (no arbitrary `Color(...)` for surfaces without reason). Proper tonal pairing (`onX` on `X`). Dark theme. **Flutter:** `ColorScheme` roles. |
| **Typography** | MD3 type scale: **Compose** `MaterialTheme.typography`; **web** typescale tokens; correct roles (Display, Headline, Title, Body, Label). |
| **Shape** | **Compose** `MaterialTheme.shapes` / component `Shape`; **web** `var(--md-sys-shape-*)`. Buttons: full; cards: medium; avoid magic numbers. |
| **Elevation** | Tonal elevation (`Surface` tonal/shadow as appropriate). **Web:** hover/focus where relevant. |
| **Components** | **Compose:** Material3 composables (`Button`, `Scaffold`, etc.). **Web:** `@material/web` or spec-aligned HTML/CSS. Correct variants. |
| **Layout** | Canonical layouts; **Compose** window size class / adaptive APIs; readable max width on large widths; foldable hinge avoidance. |
| **Navigation** | Bar / rail / drawer / drawers+**Compose** `NavHost` patterns per size class; predictive back where applicable. |
| **Motion** | **Compose** `MotionScheme` / expressive APIs when used; transitions may still use easing/duration. **Web:** CSS motion tokens fallback. |
| **Accessibility** | MD3 roles help, but **verify contrast**: UI components often need **3:1** for large text/borders and **4.5:1** for normal text (WCAG 2.x). TalkBack/semantics (Compose), focus order, touch targets (~48dp). **Web:** ARIA, keyboard. |
| **Theming** | **Compose:** `MaterialTheme` + light/dark/dynamic as designed. **Web:** CSS custom properties on `:root` or subtree. **Flutter:** `ThemeData` + `ColorScheme`. |

3. **Generate the report**:

```
# MD3 Compliance Audit Report

Target: [URL or file path]
Date: [date]
Overall Score: [X/100]

## Scores by Category
| Category       | Score | Status |
|----------------|-------|--------|
| Color tokens   | X/10  | [pass/warn/fail] |
| Typography     | X/10  | [pass/warn/fail] |
| Shape          | X/10  | [pass/warn/fail] |
| Elevation      | X/10  | [pass/warn/fail] |
| Components     | X/10  | [pass/warn/fail] |
| Layout         | X/10  | [pass/warn/fail] |
| Navigation     | X/10  | [pass/warn/fail] |
| Motion         | X/10  | [pass/warn/fail] |
| Accessibility  | X/10  | [pass/warn/fail] |
| Theming        | X/10  | [pass/warn/fail] |

## Critical Issues
[List items scoring 0-3 with specific file:line references and fixes]

## Warnings
[List items scoring 4-6 with recommendations]

## Passing
[List items scoring 7-10 with notes on what's done well]

## Recommended Fixes (Priority Order)
1. [Most impactful fix first]
2. ...
```

### Audit Methods

**For a live URL** (browser or devtools):
- Inspect computed styles and CSS variables (`--md-sys-*`)
- Resize viewport or use responsive mode for breakpoints
- Capture screenshots at key widths if helpful

**For source code** (file paths provided):
- **Compose/Kotlin:** `.kt` files — `MaterialTheme`, composables, `Color(0x…)` abuse, hard-coded `Dp`, missing `Modifier.semantics` where needed
- **Flutter:** `.dart` — `ThemeData`, `ColorScheme`
- **Web:** HTML/JSX/Vue/Svelte; CSS/SCSS for tokens
- Check **web** imports for `@material/web` vs `@material/mdc-*` (MD2)

**Quick checks** (adapt paths to your stack):
```
# Web: hardcoded colors
grep -rn '#[0-9a-fA-F]\{3,8\}' --include='*.css' --include='*.scss'

# Compose: raw Color(...) audits (sample — tune for your codebase)
grep -rn 'Color(0x' --include='*.kt'

# MD2 on web
grep...