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AWC UI

Button Group

A set of related buttons that behave as one control. It wraps md-button / md-icon-button children, forces them into toggle mode, and owns selection, roving tabindex, arrow-key navigation and — in connected mode — the fused container shape.

Live preview Open in Storybook
Show code for each technology 
<!-- index.html <head> — the icon font the components draw from -->
<link rel="stylesheet"
  href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap">

<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<md-button-group variant="connected" selection-mode="single-select" required aria-label="Text alignment">
  <md-icon-button value="left" icon="format_align_left" aria-label="Align left" selected></md-icon-button>
  <md-icon-button value="center" icon="format_align_center" aria-label="Align center"></md-icon-button>
  <md-icon-button value="right" icon="format_align_right" aria-label="Align right"></md-icon-button>
  <md-icon-button value="justify" icon="format_align_justify" aria-label="Justify"></md-icon-button>
</md-button-group>

Install

Section titled “Install”

Already installed? See the Installation guide for one-time package setup (core + tokens, fonts). Each tab below shows two patterns for using md-button-group in your project: Option A registers every AWC UI component at once (simplest), Option B imports only this component for tree-shake-friendly bundles. 

<!-- ─── Option A: global registration (all components) ─── -->
<script type="module">
  import '@awc-ui/core/define';
</script>


<!-- ─── Option B: single import (tree-shake only md-button-group) ─── -->
<script type="module">
  import '@awc-ui/core/components/md-button-group';
</script>


<md-button-group></md-button-group>

When to use

Section titled “When to use”
  • 2–5 related actions or states that read as one unit: text alignment, zoom in/out/reset, view mode.
  • You want arrow-key navigation and a single tab stop for the cluster.
  • The buttons should visually respond to one another (connected).

When not to use

Section titled “When not to use”
SituationUse instead
Choosing between 2–5 exclusive view/mode options with labelsmd-segmented-button
A default action plus variations of itmd-split-button
Unrelated actions that happen to sit near each otherSeparate md-buttons
Form field selection bound to a <form>md-radio / md-checkbox
Many options, or options that need a menumd-menu, md-select
Navigating between destinationsmd-tabs, md-navigation-bar
A single actionmd-button

The group takes over its children

Section titled “The group takes over its children”

This is the part that surprises people.

  • It sets toggle = true on every child — you never set it yourself.
  • It owns connectedLeft, connectedRight, groupTabindex and value positioning. Setting those by hand breaks the roving tabindex and the border trimming.
  • Every child needs a value. It is the identity carried in values, added and removed.
  • Children self-toggle on click first, then the group reconciles. In single-select it deselects the others; with required it re-selects the clicked button if the click would have emptied the selection.
  • Only md-button and md-icon-button children are discovered. Anything else is ignored.
Identical children — the row above is loose, the row below is grouped
loose
Day Week Month
grouped Day Week Month
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display:grid;grid-template-columns:auto 1fr;gap:14px 16px;align-items:center;">
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">loose</span>
  <div style="display:flex;gap:12px;flex-wrap:wrap;align-items:center;">
    <md-button variant="tonal" value="a">Day</md-button>
    <md-button variant="tonal" value="b">Week</md-button>
    <md-button variant="tonal" value="c">Month</md-button>
  </div>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">grouped</span>
  <md-button-group selection-mode="single-select" aria-label="Range">
    <md-button variant="tonal" value="a">Day</md-button>
    <md-button variant="tonal" value="b" selected>Week</md-button>
    <md-button variant="tonal" value="c">Month</md-button>
  </md-button-group>
</div>

The markup for the children is the same in both rows. Grouping is what makes them toggle, share one tab stop, and coordinate their selection. Tab into each row to feel the difference: the loose row has three tab stops, the grouped row has one.

Variants

Section titled “Variants”

standard spaces the children with a gap. connected fuses them into one container and drives the inner corner radii.

Standard and connected
Day Week Month Day Week Month
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display: flex; flex-direction: column; gap: 20px;">
  <md-button-group variant="standard" aria-label="Standard view mode">
    <md-button value="day">Day</md-button>
    <md-button value="week" selected>Week</md-button>
    <md-button value="month">Month</md-button>
  </md-button-group>

  <md-button-group variant="connected" aria-label="Connected view mode">
    <md-button value="day">Day</md-button>
    <md-button value="week" selected>Week</md-button>
    <md-button value="month">Month</md-button>
  </md-button-group>
</div>

Selection modes

Section titled “Selection modes”

single-select (the default) behaves like a radio group — role radiogroup, one selection at a time. multi-select allows several at once and uses role group.

Single-select alignment (required), multi-select text styles
Show code for each technology 
<!-- index.html <head> — the icon font the components draw from -->
<link rel="stylesheet"
  href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap">

<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display: flex; flex-direction: column; gap: 20px;">
  <md-button-group selection-mode="single-select" variant="connected" required aria-label="Text alignment">
    <md-icon-button value="left" icon="format_align_left" aria-label="Align left" selected></md-icon-button>
    <md-icon-button value="center" icon="format_align_center" aria-label="Align center"></md-icon-button>
    <md-icon-button value="right" icon="format_align_right" aria-label="Align right"></md-icon-button>
  </md-button-group>

  <md-button-group selection-mode="multi-select" variant="connected" aria-label="Text style">
    <md-icon-button value="bold" icon="format_bold" aria-label="Bold" selected></md-icon-button>
    <md-icon-button value="italic" icon="format_italic" aria-label="Italic"></md-icon-button>
    <md-icon-button value="underline" icon="format_underlined" aria-label="Underline" selected></md-icon-button>
  </md-button-group>
</div>

required prevents the selection from ever emptying — the right choice for a mode switch where “nothing selected” is meaningless.

Sizes

Section titled “Sizes”

Set size on the group. It assigns that size to every child on load and on every change — the same five rungs as md-button, and the same trap: the default is sm, not md. A per-child size does not survive; see Group-owned child props.

xs, sm (default), md, lg
Day Week Month Day Week Month Day Week Month Day Week Month
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display: flex; flex-direction: column; gap: 16px; align-items: flex-start;">
  <md-button-group size="xs" variant="connected" aria-label="Extra small">
    <md-button value="a" selected>Day</md-button>
    <md-button value="b">Week</md-button>
    <md-button value="c">Month</md-button>
  </md-button-group>

  <md-button-group size="sm" variant="connected" aria-label="Small">
    <md-button value="a" selected>Day</md-button>
    <md-button value="b">Week</md-button>
    <md-button value="c">Month</md-button>
  </md-button-group>

  <md-button-group size="md" variant="connected" aria-label="Medium">
    <md-button value="a" selected>Day</md-button>
    <md-button value="b">Week</md-button>
    <md-button value="c">Month</md-button>
  </md-button-group>

  <md-button-group size="lg" variant="connected" aria-label="Large">
    <md-button value="a" selected>Day</md-button>
    <md-button value="b">Week</md-button>
    <md-button value="c">Month</md-button>
  </md-button-group>
</div>

Shapes

Section titled “Shapes”

shape is set on the group and assigned to every child, exactly like size — so a group is always one shape throughout. That matches M3, which reserves shape variation for genuinely key interactions, not decoration.

Round and square, standard and connected
Round Round Round Square Square Square Square Square Square
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display: flex; flex-direction: column; gap: 20px;">
  <md-button-group shape="round" variant="standard" aria-label="Round standard">
    <md-button value="a" selected>Round</md-button>
    <md-button value="b">Round</md-button>
    <md-button value="c">Round</md-button>
  </md-button-group>

  <md-button-group shape="square" variant="standard" aria-label="Square standard">
    <md-button value="a" selected>Square</md-button>
    <md-button value="b">Square</md-button>
    <md-button value="c">Square</md-button>
  </md-button-group>

  <md-button-group shape="square" variant="connected" aria-label="Square connected">
    <md-button value="a" selected>Square</md-button>
    <md-button value="b">Square</md-button>
    <md-button value="c">Square</md-button>
  </md-button-group>
</div>

Full width

Section titled “Full width”

full-width stretches the group to its container and splits the space equally between the children (flex: 1 1 0). It keeps a connected group tidy when translated labels change width.

Full width, and a max-width cap
Day Week Month Year Day Week Month
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="inline-size: 100%; display: flex; flex-direction: column; gap: 20px;">
  <md-button-group full-width variant="connected" aria-label="Full width range">
    <md-button value="day">Day</md-button>
    <md-button value="week" selected>Week</md-button>
    <md-button value="month">Month</md-button>
    <md-button value="year">Year</md-button>
  </md-button-group>

  <md-button-group variant="connected" aria-label="Capped width range" style="--md-button-group-max-width: 320px;">
    <md-button value="day">Day</md-button>
    <md-button value="week" selected>Week</md-button>
    <md-button value="month">Month</md-button>
  </md-button-group>
</div>

Mixed children

Section titled “Mixed children”

md-button and md-icon-button can sit in the same group. Every icon-only child needs its own aria-label.

A labelled button alongside icon-only children
Preview
Show code for each technology 
<!-- index.html <head> — the icon font the components draw from -->
<link rel="stylesheet"
  href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap">

<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<md-button-group variant="connected" selection-mode="multi-select" aria-label="Editor tools">
  <md-button value="preview" icon="visibility">Preview</md-button>
  <md-icon-button value="grid" icon="grid_on" aria-label="Show grid"></md-icon-button>
  <md-icon-button value="ruler" icon="straighten" aria-label="Show rulers"></md-icon-button>
</md-button-group>

Events

Section titled “Events”
EventCancelableDetailFires
mdSelectionChangenoMdButtonGroupChangeDetailEvery user activation that lands on a discovered child

The group does not compare the new selection with the old one before emitting. Re-pressing the already-selected child of a required single-select group still fires, with added: [] and removed: [] — guard on the diff, not on the event, if a no-op should be ignored.

interface MdButtonGroupChangeDetail {
  values: string[];        // full selection snapshot AFTER the change
  added: string[];         // newly selected (usually 0–1)
  removed: string[];       // newly deselected (usually 0–1)
  originalEvent: MouseEvent;
}

The event bubbles and is composed. Listen on the group — not on each child’s mdClick, which fires before the group reconciles.

mdSelectionChange — press a button to see values, added and removed
Bold Italic Underline press a button to see the detail
Show code for each technology 
<md-button-group id="style" selection-mode="multi-select" aria-label="Text style">
<md-button variant="tonal" value="bold" icon="format_bold">Bold</md-button>
<md-button variant="tonal" value="italic" icon="format_italic" selected>Italic</md-button>
<md-button variant="tonal" value="underline" icon="format_underlined">Underline</md-button>
</md-button-group>

<script type="module">
document.getElementById('style').addEventListener('mdSelectionChange', (e) => {
  const { values, added, removed } = e.detail;
  applyStyles(values);          // full snapshot after the change
});
</script>

values is the full snapshot after the change, not a delta — apply it wholesale rather than reconciling added/removed yourself. Those two are there for the cases where the transition matters, such as animating the button that just turned off.

One click, three events

Section titled “One click, three events”

The group puts its children in toggle mode, so a single press produces a cascade. All three bubble and are composed, so a listener on the group receives every one of them — which is what you see in Storybook’s Actions panel:

OrderEventTargetDetail
1mdClickthe child{ value, toggle, selected, href, target, originalEvent }
2mdChangethe child{ selected, value }
3mdSelectionChangethe group{ values, added, removed, originalEvent }
One press, three events — switch rows and watch the deselected value appear only on line 3
Day Week Month Press a button you have not selected — one press, three events.
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<md-button-group id="range" variant="connected" selection-mode="single-select" required aria-label="Range">
  <md-button variant="tonal" value="day">Day</md-button>
  <md-button variant="tonal" value="week" selected>Week</md-button>
  <md-button variant="tonal" value="month">Month</md-button>
</md-button-group>
<output id="range-log">Press a button you have not selected — one press, three events.</output>

<script type="module">
  var group = document.getElementById('range');
  var log = document.getElementById('range-log');
  var lines = [];

  function push(line) {
    lines.push(line);
    log.textContent = lines.join(String.fromCharCode(10));
  }

  // One listener per event, all three on the GROUP: the child events bubble
  // and are composed, so they reach it too.
  group.addEventListener('mdClick', function (e) {
    lines = [];
    push('1  mdClick  (child)  value=' + e.detail.value + '  selected(next)=' + e.detail.selected);
  });

  group.addEventListener('mdChange', function (e) {
    push('2  mdChange  (child)  value=' + e.detail.value + '  selected=' + e.detail.selected);
  });

  group.addEventListener('mdSelectionChange', function (e) {
    var d = e.detail;
    push('3  mdSelectionChange  (group)  values=[' + d.values.join(', ') +
      ']  added=[' + d.added.join(', ') + ']  removed=[' + d.removed.join(', ') + ']');
  });
</script>

Listen to the child events only when you genuinely care about the press itself. On an md-button child mdClick is cancelable, so that is where you veto an activation before the group reconciles. On an md-icon-button child it is not — the group below is icon-only, so nothing here can be vetoed; it just reads the group’s own selection.

The wiring below, running — press an alignment and the paragraph follows

A button group is one control, so it reports one selection. Press an alignment and this paragraph follows it.

Show code for each technology 
<!-- index.html <head> — the icon font the components draw from -->
<link rel="stylesheet"
  href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap">

<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<md-button-group id="align" variant="connected" required aria-label="Text alignment">
  <md-icon-button value="left" icon="format_align_left" aria-label="Align left" selected></md-icon-button>
  <md-icon-button value="center" icon="format_align_center" aria-label="Align center"></md-icon-button>
  <md-icon-button value="right" icon="format_align_right" aria-label="Align right"></md-icon-button>
</md-button-group>
<p id="align-sample">A button group is one control, so it reports one selection.</p>

<script type="module">
  var group = document.getElementById('align');
  var sample = document.getElementById('align-sample');

  group.addEventListener('mdSelectionChange', function (e) {
    // values is the snapshot; single-select means it holds at most one entry.
    sample.style.textAlign = e.detail.values[0] || 'left';
  });
</script>
<md-button-group id="align" variant="connected" required aria-label="Text alignment">
<md-icon-button value="left" icon="format_align_left" aria-label="Align left" selected></md-icon-button>
<md-icon-button value="center" icon="format_align_center" aria-label="Align center"></md-icon-button>
<md-icon-button value="right" icon="format_align_right" aria-label="Align right"></md-icon-button>
</md-button-group>

<script type="module">
document.getElementById('align').addEventListener('mdSelectionChange', (e) => {
  const { values, added, removed } = e.detail;
  applyAlignment(values[0]);
});
</script>

API Reference

Section titled “API Reference”

Properties

PropertyAttributeTypeDefaultReflects
variantvariant'standard' | 'connected''standard'—
sizesize'xs' | 'sm' | 'md' | 'lg' | 'xl''sm'—
shapeshape'round' | 'square''round'—
selectionModeselection-mode'single-select' | 'multi-select''single-select'—
requiredrequiredbooleanfalse—
fullWidthfull-widthbooleanfalseYes
densitydensity0 | -1 | -2 | -3 | -40Yes

Slots

SlotDescription
(default)—

CSS Custom Properties

Override on the host element for per-instance theming:

PropertyDescription
--md-button-group-gapOverride default gap
--md-button-group-widthExplicit inline-size (defaults to auto)
--md-button-group-min-widthMinimum inline-size
--md-button-group-max-widthMaximum inline-size
--md-button-group-heightExplicit block-size (defaults to auto)
--md-button-group-min-heightMinimum block-size
--md-button-group-max-heightMaximum block-size
--md-button-group-_unset—

Accessibility

Section titled “Accessibility”
  • Role is radiogroup in single-select and group in multi-select. Children expose aria-pressed through their own toggle mode.
  • One tab stop for the whole cluster (roving tabindex). In single-select the selected child is the tab stop.
  • ArrowLeft / ArrowRight move focus, Home / End jump to the ends.
  • Give the group itself an aria-label describing what it controls (“Text alignment”), and every icon-only child its own aria-label.
  • required prevents an empty selection, which keeps the radiogroup semantics honest.
Tab once to enter, then arrow between children
radiogroup group
Show code for each technology 
<!-- index.html <head> — the icon font the components draw from -->
<link rel="stylesheet"
  href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap">

<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display:grid;grid-template-columns:auto 1fr;gap:14px 16px;align-items:center;">
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">radiogroup</span>
  <md-button-group selection-mode="single-select" aria-label="Text alignment">
    <md-icon-button value="left" icon="format_align_left" aria-label="Align left" selected></md-icon-button>
    <md-icon-button value="center" icon="format_align_center" aria-label="Align centre"></md-icon-button>
    <md-icon-button value="right" icon="format_align_right" aria-label="Align right"></md-icon-button>
  </md-button-group>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">group</span>
  <md-button-group selection-mode="multi-select" aria-label="Text style">
    <md-icon-button value="bold" icon="format_bold" aria-label="Bold"></md-icon-button>
    <md-icon-button value="italic" icon="format_italic" aria-label="Italic" selected></md-icon-button>
    <md-icon-button value="underline" icon="format_underlined" aria-label="Underline"></md-icon-button>
  </md-button-group>
</div>

Both rows above are one tab stop each. Tab moves you into the group and straight out again; ArrowLeft / ArrowRight move within it and Home / End jump to the ends — the composite-widget pattern, not three separate stops.

The role changes with the mode: single-select is a radiogroup, multi-select is a plain group. Every child here is icon-only, so each carries its own aria-label, and the group carries one describing what it controls.

RTL, density & i18n

Section titled “RTL, density & i18n”

RTL — arrow direction follows reading order, not screen order. Under dir="rtl", ArrowRight moves toward the start of the group. Connected corner rounding flips with the layout. Directional child icons still need their own mirror-icon handling. See RTL.

<div dir="rtl">
  <md-button-group variant="connected" required aria-label="محاذاة النص">…</md-button-group>
</div>
Same markup, dir=ltr vs dir=rtl
ltr
Day Week Month
rtl
يوم أسبوع شهر
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display:grid;grid-template-columns:auto 1fr;gap:14px 16px;align-items:center;">
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">ltr</span>
  <div dir="ltr">
    <md-button-group variant="connected" selection-mode="single-select" aria-label="Range">
      <md-button variant="tonal" value="day">Day</md-button>
      <md-button variant="tonal" value="week" selected>Week</md-button>
      <md-button variant="tonal" value="month">Month</md-button>
    </md-button-group>
  </div>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">rtl</span>
  <div dir="rtl">
    <md-button-group variant="connected" selection-mode="single-select" aria-label="Range">
      <md-button variant="tonal" value="day">يوم</md-button>
      <md-button variant="tonal" value="week" selected>أسبوع</md-button>
      <md-button variant="tonal" value="month">شهر</md-button>
    </md-button-group>
  </div>
</div>

The connected corner rounding flips too: the first child keeps the leading corners rounded in both directions, so the group never looks inside-out.

An Arabic connected icon group — tab in, then arrow through it
Show code for each technology 
<!-- index.html <head> — the icon font the components draw from -->
<link rel="stylesheet"
  href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200&display=swap">

<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div dir="rtl" style="inline-size: 100%;">
  <md-button-group variant="connected" required aria-label="محاذاة النص">
    <md-icon-button value="left" icon="format_align_left" aria-label="محاذاة لليسار" selected></md-icon-button>
    <md-icon-button value="center" icon="format_align_center" aria-label="توسيط"></md-icon-button>
    <md-icon-button value="right" icon="format_align_right" aria-label="محاذاة لليمين"></md-icon-button>
  </md-button-group>
</div>

Do not hand-reverse the children for RTL

Section titled “Do not hand-reverse the children for RTL”

Arrow keys follow reading order, not screen order. In RTL, ArrowLeft moves to the next button because next is to the left. The component already handles that, so writing the children in reverse order for RTL flips them twice: the group reads Month → Day, and Home lands on Month.

Correct: children in logical order — wrong: children hand-reversed under dir=rtl
correct
Day Week Month
wrong
Month Week Day
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display:grid;grid-template-columns:auto 1fr;gap:14px 16px;align-items:center;">
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">correct</span>
  <div dir="rtl">
    <md-button-group variant="connected" selection-mode="single-select" aria-label="Range, logical order">
      <md-button variant="tonal" value="day">Day</md-button>
      <md-button variant="tonal" value="week" selected>Week</md-button>
      <md-button variant="tonal" value="month">Month</md-button>
    </md-button-group>
  </div>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">wrong</span>
  <div dir="rtl">
    <md-button-group variant="connected" selection-mode="single-select" aria-label="Range, hand-reversed">
      <md-button variant="tonal" value="month">Month</md-button>
      <md-button variant="tonal" value="week" selected>Week</md-button>
      <md-button variant="tonal" value="day">Day</md-button>
    </md-button-group>
  </div>
</div>

Every density rung

Section titled “Every density rung”
density on the group cascades to every child
0 Day Week Month -1 Day Week Month -2 Day Week Month -3 Day Week Month -4 Day Week Month
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display:grid;grid-template-columns:auto 1fr;gap:14px 16px;align-items:center;">
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">0</span>
  <md-button-group variant="connected" selection-mode="single-select" density="0" aria-label="Range">
    <md-button variant="tonal" value="day">Day</md-button>
    <md-button variant="tonal" value="week" selected>Week</md-button>
    <md-button variant="tonal" value="month">Month</md-button>
  </md-button-group>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">-1</span>
  <md-button-group variant="connected" selection-mode="single-select" density="-1" aria-label="Range">
    <md-button variant="tonal" value="day">Day</md-button>
    <md-button variant="tonal" value="week" selected>Week</md-button>
    <md-button variant="tonal" value="month">Month</md-button>
  </md-button-group>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">-2</span>
  <md-button-group variant="connected" selection-mode="single-select" density="-2" aria-label="Range">
    <md-button variant="tonal" value="day">Day</md-button>
    <md-button variant="tonal" value="week" selected>Week</md-button>
    <md-button variant="tonal" value="month">Month</md-button>
  </md-button-group>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">-3</span>
  <md-button-group variant="connected" selection-mode="single-select" density="-3" aria-label="Range">
    <md-button variant="tonal" value="day">Day</md-button>
    <md-button variant="tonal" value="week" selected>Week</md-button>
    <md-button variant="tonal" value="month">Month</md-button>
  </md-button-group>
  <span style="inline-size:4rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">-4</span>
  <md-button-group variant="connected" selection-mode="single-select" density="-4" aria-label="Range">
    <md-button variant="tonal" value="day">Day</md-button>
    <md-button variant="tonal" value="week" selected>Week</md-button>
    <md-button variant="tonal" value="month">Month</md-button>
  </md-button-group>
</div>

Set density on the group, not on each child — it cascades, and mixing the two is how you get a connected group whose segments no longer line up.

Density and direction together

Section titled “Density and direction together”
dir and density are independent — the corners flip, the rungs taper
ltr · 0
Day Week Month
rtl · 0
يوم أسبوع شهر
ltr · -3
Day Week Month
rtl · -3
يوم أسبوع شهر
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display:grid;grid-template-columns:auto 1fr;gap:14px 16px;align-items:center;">
  <span style="inline-size:5.5rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">ltr · 0</span>
  <div dir="ltr">
    <md-button-group variant="connected" selection-mode="single-select" density="0" aria-label="Range">
      <md-button variant="tonal" value="day">Day</md-button>
      <md-button variant="tonal" value="week" selected>Week</md-button>
      <md-button variant="tonal" value="month">Month</md-button>
    </md-button-group>
  </div>
  <span style="inline-size:5.5rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">rtl · 0</span>
  <div dir="rtl">
    <md-button-group variant="connected" selection-mode="single-select" density="0" aria-label="النطاق">
      <md-button variant="tonal" value="day">يوم</md-button>
      <md-button variant="tonal" value="week" selected>أسبوع</md-button>
      <md-button variant="tonal" value="month">شهر</md-button>
    </md-button-group>
  </div>
  <span style="inline-size:5.5rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">ltr · -3</span>
  <div dir="ltr">
    <md-button-group variant="connected" selection-mode="single-select" density="-3" aria-label="Range">
      <md-button variant="tonal" value="day">Day</md-button>
      <md-button variant="tonal" value="week" selected>Week</md-button>
      <md-button variant="tonal" value="month">Month</md-button>
    </md-button-group>
  </div>
  <span style="inline-size:5.5rem;opacity:.65;font-size:.75rem;font-family:ui-monospace,monospace;">rtl · -3</span>
  <div dir="rtl">
    <md-button-group variant="connected" selection-mode="single-select" density="-3" aria-label="النطاق">
      <md-button variant="tonal" value="day">يوم</md-button>
      <md-button variant="tonal" value="week" selected>أسبوع</md-button>
      <md-button variant="tonal" value="month">شهر</md-button>
    </md-button-group>
  </div>
</div>

Translated labels change width

Section titled “Translated labels change width”
English, German, and German at full-width
Day Week Month Tag Woche Monat Tag Woche Monat
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<div style="display:flex;flex-direction:column;gap:14px;align-items:flex-start;">
  <md-button-group variant="connected" selection-mode="single-select" aria-label="Range">
    <md-button variant="tonal" value="day">Day</md-button>
    <md-button variant="tonal" value="week" selected>Week</md-button>
    <md-button variant="tonal" value="month">Month</md-button>
  </md-button-group>
  <md-button-group variant="connected" selection-mode="single-select" aria-label="Zeitraum">
    <md-button variant="tonal" value="day">Tag</md-button>
    <md-button variant="tonal" value="week" selected>Woche</md-button>
    <md-button variant="tonal" value="month">Monat</md-button>
  </md-button-group>
  <md-button-group variant="connected" selection-mode="single-select" full-width aria-label="Zeitraum, full width">
    <md-button variant="tonal" value="day">Tag</md-button>
    <md-button variant="tonal" value="week" selected>Woche</md-button>
    <md-button variant="tonal" value="month">Monat</md-button>
  </md-button-group>
</div>

The third row shows the fix when translation makes a connected group ragged: full-width divides the container evenly, so segment widths stop depending on label length.

Density — density="-1…-4" on the group cascades to every child, tapering the gap in standard and the child height in both variants. See Density.

i18n — child labels and aria-labels come from your dictionary; the group needs its own aria-label too. Translated labels change width, so reach for full-width when a connected group has to stay even.

Theming

Section titled “Theming”
Custom propertyPurposeDefault
--md-button-group-gapSpacing between childrenstandard, per size: 18px (xs), 12px (sm — the default), 8px (md/lg/xl), each tapering to roughly half across the density range. connected: a fixed 2px seam that does not taper
--md-button-group-width / -min-width / -max-widthInline-size boundsauto / auto / none
--md-button-group-height / -min-height / -max-heightBlock-size boundsauto / auto / none

Per-button appearance is themed with the children’s own --md-button-* / --md-icon-button-* properties — the group exposes no CSS parts.

A widened gap
Day Week Month
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<md-button-group variant="standard" aria-label="Wide gap" style="--md-button-group-gap: 20px;">
  <md-button value="a" selected>Day</md-button>
  <md-button value="b">Week</md-button>
  <md-button value="c">Month</md-button>
</md-button-group>

The group owns layout; colour still comes from the children, so a themed group is a themed set of md-buttons inside a sized container:

Child colours, group gap, and an explicit group width
Day Week Month Tight 2px gap Fixed 420px wide
Show code for each technology 
<!-- index.html — register the AWC UI elements once -->
<script type="module">
  import '@awc-ui/core/define';
</script>

<style>
  .bg-brand md-button:not(.md-button--selected) {
  --md-button-container-color: #1B5E20;
  --md-button-label-color: #FFFFFF;
  }
  .bg-brand md-button.md-button--selected {
  --md-button-container-color: #A5D6A7;
  --md-button-label-color: #0B3D0F;
  }
</style>
<div style="display:flex;flex-direction:column;gap:14px;align-items:flex-start;">
  <md-button-group class="bg-brand" variant="connected" selection-mode="single-select" aria-label="Brand-themed">
    <md-button variant="filled" value="a">Day</md-button>
    <md-button variant="filled" value="b" selected>Week</md-button>
    <md-button variant="filled" value="c">Month</md-button>
  </md-button-group>
  <md-button-group variant="standard" selection-mode="single-select" style="--md-button-group-gap: 2px;" aria-label="Tight gap">
    <md-button variant="tonal" value="a">Tight</md-button>
    <md-button variant="tonal" value="b" selected>2px</md-button>
    <md-button variant="tonal" value="c">gap</md-button>
  </md-button-group>
  <md-button-group variant="connected" selection-mode="single-select" style="--md-button-group-width: 420px;" aria-label="Fixed width">
    <md-button variant="tonal" value="a">Fixed</md-button>
    <md-button variant="tonal" value="b" selected>420px</md-button>
    <md-button variant="tonal" value="c">wide</md-button>
  </md-button-group>
</div>
/* Geometry on the group, colour on the children. */
.toolbar-range {
  --md-button-group-gap: 2px;
  --md-button-group-max-width: 420px;
}


/* The host class tracks the selection; the `selected` attribute does not. */
.toolbar-range md-button.md-button--selected {
  --md-button-container-color: var(--md-sys-color-secondary-container);
  --md-button-label-color: var(--md-sys-color-on-secondary-container);
}
Section titled “Related”

md-button · md-icon-button · md-segmented-button · md-split-button · md-toolbar · md-tabs

AI / LLM Context

Section titled “AI / LLM Context”

For AI Agents — md-button-group

Two artefacts to give your AI agent so it generates correct UI with this component. The per-component spec answers "how do I use this exact tag?". The main-llm spec answers "which tag should I pick in the first place?".

Per-component

md-button-group spec card

Identity · when to use / when NOT · decision cues · behavioural contract · do/don't · anti-patterns · full API. Paste into your agent when you're implementing with this component.

Main-LLM spec

AWC UI Operator's Manual

System-prompt preamble · decision matrix · token reference · page recipes · anti-patterns. Paste into the system prompt at the start of a piece of work.

Open spec

md-button-group readme.md 

# md-button-group

<!-- llm:meta
tag: md-button-group
category: actions
status: md3-mapped
m3-guidelines: https://m3.material.io/components/button-groups/guidelines
form-associated: false
depends-on: none
used-by: none
accepts-children: md-button, md-icon-button
-->

**A set of related buttons that behave as one control.** Wraps `md-button` /
`md-icon-button` children, forces them into toggle mode, and manages selection,
roving tabindex, arrow-key navigation, and — in `connected` mode — the fused
container shape.

> Setup, theming, density and i18n are configured once for the whole library —
> see [`main-llm.md`](../../../../../main-llm.md) at the repo root.

---

## When to use

- 2–5 **related** actions or states that read as one unit: text alignment,
  zoom in/out/reset, view mode.
- You want **arrow-key navigation** and a single tab stop for the cluster.
- The buttons should visually respond to one another (`connected`).

## When NOT to use

| Situation | Use instead |
|---|---|
| Choosing between 2–5 exclusive **view/mode** options with labels | `md-segmented-button-set` |
| A default action plus variations of it | `md-split-button` |
| Unrelated actions that happen to sit near each other | Separate `md-button`s |
| Form field selection bound to a `<form>` | `md-radio` / `md-checkbox` |
| Many options, or options that need a menu | `md-menu`, `md-select` |
| Navigating between destinations | `md-tabs`, `md-navigation-bar` |
| A single action | `md-button` |

## Decision cues

| Need | Setting |
|---|---|
| Spaced buttons that still act as a group | `variant="standard"` (default) |
| Fused, single-container look | `variant="connected"` |
| One selection at a time | `selection-mode="single-select"` (default) |
| Several at once (e.g. bold + italic) | `selection-mode="multi-select"` |
| Never allow an empty selection | `required` |
| Stretch across the container, children sharing space | `full-width` |

## API contract

```html
<md-button-group
  variant="standard|connected"                 <!-- default: standard -->
  size="xs|sm|md|lg|xl"                         <!-- default: sm -->
  shape="round|square"                          <!-- default: round -->
  selection-mode="single-select|multi-select"   <!-- default: single-select -->
  required
  full-width
  density="-1|-2|-3|-4"
  aria-label="Text alignment"
>
  <md-icon-button value="left"   icon="format_align_left"   aria-label="Align left"></md-icon-button>
  <md-icon-button value="center" icon="format_align_center" aria-label="Align center"></md-icon-button>
  <md-icon-button value="right"  icon="format_align_right"  aria-label="Align right"></md-icon-button>
</md-button-group>
```

`density` is only meaningful at `-1`…`-4`; rung `0` is the uncompacted default
and there is no CSS rule for it, so writing `density="0"` does nothing (it does
**not** opt the group out of an inherited `data-density` ancestor).

**Slots** — `(default)`: `md-button` and/or `md-icon-button` children. No named
slots.

**Methods** — none.

**Parts** — none. The group renders only a `<slot>`; style the children through
their own `--md-button-*` / `--md-icon-button-*` properties.

**Events**

| Event | Detail | Bubbles / composed | Fires |
|---|---|---|---|
| `mdSelectionChange` | `MdButtonGroupChangeDetail` | yes / yes | On every user activation of a child button |

`mdSelectionChange` is the only event this component **declares**. Child events
also reach a listener on the group, since they bubble and are composed — but
*which* ones depends on the child element:

| Child | Events it emits | One press reaches the group as |
|---|---|---|
| `md-icon-button` | `mdClick` only | `mdClick` (child) → `mdSelectionChange` (group) |
| `md-button` | `mdClick`, `mdChange` | `mdClick` (child, cancelable) → `mdChange` (child) → `mdSelectionChange` (group) |

**`md-icon-button` has no `mdChange`.** A listener for it on an icon-button
child never fires. Since icon-button children are the common case for a
connected group, prefer `mdSelectionChange` on the group — it is emitted for
either child type.

**Listen on the group, not the children.** Switching from `a` to `b` in a
`single-select` group of `md-button`s fires one `mdChange`, not two: it fires
only for the button you pressed, and the one turned off emits nothing — the
group clears it programmatically and `md-button` has no watcher on `selected`.
Only `mdSelectionChange` reports `removed: ['a']`. This matches native radio
inputs, where the deselected radio also fires no `change`.

```ts
interface MdButtonGroupChangeDetail {
  values: string[];        // full selection snapshot after the change
  added: string[];         // newly selected (usually 0–1)
  removed: string[];       // newly deselected (usually 0–1)
  originalEvent: MouseEvent;
}
```

### Behavioral contract worth knowing

- The group **overwrites its children.** On load, on any `variant` / `size` /
  `shape` / `selection-mode` / `required` change, and whenever its child list
  mutates, it writes `toggle = true`, `shape`, `size`, `connectedLeft` and
  `connectedRight` onto every child. A `size` or `shape` set on a child is
  replaced by the group's — set them on the group instead.
- `groupTabindex` is owned by the group as well. Never set it, `connected-left`
  or `connected-right` by hand.
- **Give every child a `value`** — it is the identity in
  `values` / `added` / `removed`. A child without one contributes an empty
  string, so several unset children become indistinguishable.
- Children **self-toggle on click first**, then the group reconciles: in
  `single-select` it deselects the others; with `required` it re-selects the
  clicked button if the click would have emptied the selection.
- `mdSelectionChange` fires on **every** activation of a child, including one
  that leaves the selection unchanged (re-clicking the selected button in a
  `required` single-select group), in which case `added` and `removed` are both
  empty. It never fires on mount.
- Keyboard: `ArrowLeft` / `ArrowRight` move focus and wrap around,
  `Home` / `End` jump to the ends, and disabled children are skipped.
  **Arrow direction is RTL-aware** — it follows reading order, resolved from the
  nearest `dir` attribute on the group or an ancestor.
- One tab stop for the whole group (roving tabindex). The active stop is the
  last focused or clicked child, else the selected child in `single-select`,
  else the first enabled child.
- Role is `radiogroup` in `single-select` (with `aria-orientation="horizontal"`)
  and `group` in `multi-select`.
- `variant="standard"` adds a press flourish: the pressed button widens by a few
  pixels (3–8px per side by `size`) and its neighbours absorb the same amount,
  so the group's total width never changes. `connected` groups do not do this.
- Children are found with `querySelectorAll('md-button, md-icon-button')`, so a
  button nested inside a wrapper element is still selected and roved — but the
  `::slotted()` shape rules and the flex layout only reach **direct** children,
  so a wrapper breaks the fused corners and the sizing.

---

## Do / Don't

Sourced from [M3 · Button groups · Guidelines](https://m3.material.io/components/button-groups/guidelines).

| ✅ Do | ❌ Don't |
|---|---|
| Use the **same shape** for every button in the group | Don't mix `round` and `square` children arbitrarily |
| Vary width and color to signal a primary action within the group | Don't mix color styles inside a **connected** group |
| Reserve shape differences for genuinely key interactions | Don't use shape variation decoratively |
| Give the primary action higher emphasis via size or color | Don't make every button in the group high-emphasis |
| Keep the group to a handful of related buttons | Don't build a toolbar out of one giant group |
| Give icon-only children an `aria-label` | Don't ship unlabelled icon children |
| Use `required` when an empty selection is meaningless | Don't allow a mode switch to end up with nothing selected |

---

## Patterns

```html
<!-- Connected, single-select: text alignment -->
<md-button-group variant="connected" selection-mode="single-select" required
                 aria-label="Text alignment">
  <md-icon-button value="left"   icon="format_align_left"   aria-label="Align left" selected></md-icon-button>
  <md-icon-button value="center" icon="format_align_center" aria-label="Align center"></md-icon-button>
  <md-icon-button value="right"  icon="format_align_right"  aria-label="Align right"></md-icon-button>
</md-button-group>

<script type="module">
  document.querySelector('md-button-group')
    .addEventListener('mdSelectionChange', (e) => {
      const [alignment] = e.detail.values;
      if (alignment) document.body.style.textAlign = alignment;
    });
</script>
```

```html
<!-- Multi-select: inline text styles -->
<md-button-group selection-mode="multi-select" variant="connected"
                 aria-label="Text style">
  <md-icon-button value="bold"      icon="format_bold"       aria-label="Bold"></md-icon-button>
  <md-icon-button value="italic"    icon="format_italic"     aria-label="Italic"></md-icon-button>
  <md-icon-button value="underline" icon="format_underlined" aria-label="Underline"></md-icon-button>
</md-button-group>

<script type="module">
  document.querySelectorAll('md-button-group')[0]
    .addEventListener('mdSelectionChange', (e) => {
      const { values, added, removed } = e.detail;
      console.log(values, 'turned on:', added, 'turned off:', removed);
    });
</script>
```

```html
<!-- Full-width, children share the space equally -->
<md-button-group full-width variant="connected" aria-label="Calendar range">
  <md-button value="day">Day</md-button>
  <md-button value="week" selected>Week</md-button>
  <md-button value="month">Month</md-button>
</md-button-group>

<!-- Capped height: the ceiling also caps each child's minimum height -->
<md-button-group size="lg" style="--md-button-group-max-height: 40px;"
                 aria-label="Zoom">
  <md-button value="out" icon="zoom_out">Out</md-button>
  <md-button value="in"  icon="zoom_in">In</md-button>
</md-button-group>
```

## Anti-patterns

| ❌ Wrong | ✅ Right | Why |
|---|---|---|
| Children without `value` | Give every child a unique `value` | The event payload is built from values; unset children all report `''`. |
| Setting `toggle` on the children | The group sets it | It is applied automatically on load and on every re-sync. |
| Setting `size` / `shape` on a child | Set them on the group | The group overwrites both on every sync. |
| Setting `connected-left` / `connected-right` / `group-tabindex` | Leave them alone | Group-owned `@internal` props; setting them breaks the border trims and the single tab stop. |
| Listening to each child's `mdClick` for selection | Listen to `mdSelectionChange` | The child fires before the group reconciles, so the state you read is not final. |
| Reading `values` as the diff | `values` is the full snapshot; use `added` / `removed` for the diff | Easy and common mix-up. |
| Treating `mdSelectionChange` as "the selection differed" | Check `added` / `removed` | It fires on every activation, even a no-op re-click. |
| Mixing `filled` and `outlined` children in a `connected` group | One color style per connected group | M3 forbids it. |
| Wrapping the children in a `<div>` for layout | Keep them direct children | The fused corner rules and flex sizing use `::slotted()`, which only matches direct children. |
| Using it for a form field | `md-radio` / `md-checkbox` | The group is not form-associated and submits nothing. |
| Assuming `ArrowRight` always moves right | It follows reading order | RTL-aware by design. |
| Expecting an initial `mdSelectionChange` | It fires only on user activation | Set the initial state with `selected` on a child. |
| `density="0"` to escape an inherited rung | `style="--md-sys-density-scale: 0"` | There is no `density="0"` rule; rung 0 is the inert default. |

## Accessibility, RTL, density, i18n

**Accessibility**
- `radiogroup` in `single-select` (plus `aria-orientation="horizontal"`),
  `group` in `multi-select`. Children expose `aria-pressed` through their own
  toggle mode.
- One tab stop for the cluster; arrows move within it — the expected pattern for
  a composite widget.
- Give the group itself an `aria-label` describing what it controls
  (e.g. "Text alignment"), and every icon-only child its own `aria-label`.
- `required` prevents an empty selection, which keeps the radiogroup semantics
  honest.

**RTL** — arrow-key direction follows reading order automatically, and the
connected corner radii use logical properties so the pill ends stay on the outer
edges. Directional child icons still need their own `mirror-icon`.

**Density** — `density="-1"`…`"-4"` on the group compacts its gap and, because
the rung is published as an inherited custom property, the children taper with
it. Prefer a global `data-density` ancestor; use the prop for one-off regions.
The connected seam stays at 2px on every rung by design.

**i18n** — child labels and `aria-label`s come from your dictionary. Translated
labels change width; `full-width` keeps a connected group tidy.

## Related components

`md-button` · `md-icon-button` · `md-segmented-button-set` ·
`md-split-button` · `md-toolbar` · `md-tabs`

## Theming

| Custom property | Purpose | Default |
|---|---|---|
| `--md-button-group-gap` | Space between children | `18px` (`xs`), `12px` (`sm`), `8px` (`md`/`lg`/`xl`), `2px` in any `connected` group |
| `--md-button-group-width` | Explicit inline-size | `auto` (`100%` with `full-width`) |
| `--md-button-group-min-width` | Inline-size floor | `auto` |
| `--md-button-group-max-width` | Inline-size ceiling | `none` |
| `--md-button-group-height` | Explicit block-size | `auto` |
| `--md-button-group-min-height` | Block-size floor | `auto` |
| `--md-button-group-max-height` | Block-size ceiling (also caps each child's minimum height, so the buttons actually shrink) | `none` |

**CSS parts** — none.

```css
/* A denser connected group with a tighter seam */
md-button-group.compact {
  --md-button-group-gap: 1px;
  --md-button-group-max-width: 320px;
}
```

<!-- Auto Generated Below -->


## Properties

| Property        | Attribute        | Description                                                                                                                                                                                                                                                                      | Type                                   | Default           |
| --------------- | ---------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------- | ----------------- |
| `density`       | `density`        | Local density rung. Drives the same `--md-sys-density-scale` signal that a global `data-density` ancestor sets, so a local value simply overrides the inherited one. 0 = default, -4 = ultra-compact.                                                                            | `-1 \| -2 \| -3 \| -4 \| 0`            | `0`               |
| `fullWidth`     | `full-width`     | When `true` the group stretches to 100% of its container's inline-size and its children share that space equally (`flex: 1 1 0`). Combine with the `--md-button-group-width` / `--md-button-group-max-width` CSS custom properties for fine-grained control over the final size. | `boolean`                              | `false`           |
| `required`      | `required`       | When true, at least one button must remain selected                                                                                                                                                                                                                              | `boolean`                              | `false`           |
| `selectionMode` | `selection-mode` | Selection mode                                                                                                                                                                                                                                                                   | `"multi-select" \| "single-select"`    | `'single-select'` |
| `shape`         | `shape`          | Default shape applied to all child buttons                                                                                                                                                                                                                                       | `"round" \| "square"`                  | `'round'`         |
| `size`          | `size`           | Button size — controls gap (standard) and inner corner radii (connected)                                                                                                                                                                                                         | `"lg" \| "md" \| "sm" \| "xl" \| "xs"` | `'sm'`            |
| `variant`       | `variant`        | Standard groups add padding between buttons; connected groups fuse them together                                                                                                                                                                                                 | `"connected" \| "standard"`            | `'standard'`      |


## Events

| Event               | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | Type                                     |
| ------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------- |
| `mdSelectionChange` | Fires every time a user activation toggles the selection state of a child button. The detail object describes both the new selection snapshot (`values`) and the diff from the previous selection (`added`, `removed`), plus the underlying `originalEvent`.  Distinct from each child button's own `mdChange` (which fires per individual button toggle); the group's `mdSelectionChange` fires once per user activation and reports the *group-level* state.  Bubbles and is composed so listeners outside the shadow tree receive it. | `CustomEvent<MdButtonGroupChangeDetail>` |


----------------------------------------------

*Built with [StencilJS](https://stenciljs.com/)*

AWC UI Operator’s Manual 

# main-llm.md — AWC UI build director

<!-- llm:meta
role: director
audience: llm
library: "@awc-ui/core"
component-count: 57
sub-component-count: 24
manual-count: 81
per-component-docs: ./packages/core/src/components/<tag>/readme.md
-->

**You are building a web app with AWC UI, a Material Design 3 web-component
library.** This file is the entry point and the only document you need before
writing UI code. Everything here is self-contained: tokens, recipes,
composition rules and the ship checklist. Per-component detail lives in
`./packages/core/src/components/<tag>/readme.md` — e.g.
[`md-button`](./packages/core/src/components/md-button/readme.md).

Your job, in order:

1. **Interview** the user (§1). Do not skip it and do not guess.
2. **Lock the configuration** their answers imply (§2) and bootstrap it (§3–§4).
3. **Route every UI need through the decision matrix** (§5) — never pick a
   component by name-similarity.
4. **Load the component's readme.md before writing a single line of its
   markup** (§6). The file is
   `./packages/core/src/components/<tag>/readme.md` — read it in full, do not
   skim it, and do not write the markup from memory of a similar library. Each
   one has a `When NOT to use`, a `Do / Don't` table sourced from
   [m3.material.io](https://m3.material.io), and an `Anti-patterns` table of
   mistakes models actually make. If you are about to use three components,
   load all three readmes first.
5. **Check what nests inside what** (§7) and start from a recipe (§8) rather
   than from a blank page.
6. **Apply the universal rules** (§9) — the API, content and accessibility
   rules every component is bound by, and the ones §10 checks you against.
7. **Run the ship checklist** (§10) before declaring done.

**Fail closed.** If you cannot satisfy a step — no component fits, a token
doesn't exist, an accessible name has nowhere to come from — say so and ask.
Do not invent an `md-*` tag, a prop, or a token. If it is not in this file or
in the component's manual, it does not exist.

---

## §1 — Interview the user

Ask these **one at a time**, in this order. Each answer closes off decisions
downstream, so don't batch them into a wall of questions. Skip a question only
if the user has already answered it unprompted.

If the user says "just pick sensible defaults", use the **bold** option and tell
them what you chose.

### 1.1 Scope and shape

1. **What is the app?** One or two sentences — domain, primary job, who uses it.
2. **What kind of surface is it?**
   - Internal tool / admin console / dashboard
   - Data-heavy CRUD application
   - Consumer-facing product
   - Marketing or content site
   - Mobile-first / PWA
3. **Which framework?** React · Angular · Vue · Svelte · **plain HTML** ·
   Next · Nuxt · SvelteKit · Astro
4. **Does it server-render?** (SSR/SSG, or **client-only SPA**)
5. **Roughly how many distinct screens**, and what are the top 3?

### 1.2 Look and feel

6. **Density** — how much information per screen?
   - `0` — **default**, comfortable, touch-friendly
   - `-1` / `-2` — compact; typical for admin consoles
   - `-3` / `-4` — ultra-compact; dense data tables, trading/ops screens
7. **Theme** — light only, dark only, or **both with a user toggle**?
   Does it follow the OS preference?
8. **Brand color** — a seed/primary color, or **stock MD3 palette**?
9. **Expressive motion** — keep **ripple and shape-morph on** (default), or turn
   them off for a flatter, more utilitarian feel?
10. **Shape language** — **rounded** (MD3 default) or squared?

### 1.3 Internationalization

11. **How many locales**, and which?
12. **Any RTL locales** (Arabic, Hebrew, Farsi, Urdu)? — this changes layout
    verification and directional-icon handling.
13. **Which i18n engine?** (i18next, vue-i18n, ngx-translate, Paraglide, custom)
    Components are engine-agnostic — you localize in the consumer layer.
14. **Locale-formatted values** — dates, numbers, currency? Which locale drives
    `Intl`?

### 1.4 Data and forms

15. **Is there significant tabular data?** How many rows, and is it
    server-paged? (Drives how you page `md-table` — it holds the state, you
    supply each page of rows.)
16. **Are there charts?** Which questions should they answer?
17. **How heavy are the forms?** Validation rules, async validation, multi-step?
18. **Rich text editing anywhere?** — ⚠️ **AWC UI has no RTE component.** If yes,
    you must integrate a third-party editor (TipTap, Lexical, Quill) and style
    it to the MD3 tokens yourself. Confirm this with the user explicitly.

### 1.5 Constraints

19. **Accessibility target** — **WCAG 2.1 AA** (what the library is tested to),
    or stricter?
20. **Browser/device support floor?**
21. **Anything already decided** you must not change — existing design system,
    router, state library, CSS approach?

---

## §2 — Map answers to configuration

| Answer | What you set |
|---|---|
| Admin console / data-heavy | `data-density="-1"` or `-2` on `<html>`; prefer `size="xs"`/`"sm"` on actions |
| Consumer / marketing | leave density alone (`0` is the default); larger button sizes (`md`/`lg`) for CTAs |
| Mobile-first | `md-navigation-bar` + `md-fab`; avoid `md-navigation-rail`, `md-transfer-list`, wide tables |
| Desktop-first | `md-navigation-rail` or `md-app-bar`; rail over bottom bar |
| Dark mode | `data-theme="dark"` on `<html>`; wire a toggle, and mirror OS via `prefers-color-scheme` |
| Both themes with toggle | persist the choice; set the attribute before first paint to avoid a flash |
| Brand color | override the `--md-sys-color-*` roles in your own stylesheet, loaded after the tokens (§4.2) |
| Flat / utilitarian | `data-ripple="off"` and `data-shape-morph="off"` on `<html>` |
| Any RTL locale | `dir="rtl"` on `<html>`; add `mirror-icon` to `md-button`s with directional glyphs; swap the glyph name yourself everywhere else (§4.5) |
| Multiple locales | build a dictionary in the consumer layer and feed component text props from it; never hardcode strings in markup |
| `Intl`-formatted values | pass a `locale` prop where a component exposes one; format everything else before it reaches the component |
| SSR | import from `@awc-ui/core/hydrate` on the server; use the client/server wrappers in `@awc-ui/react` |
| Heavy forms | components are form-associated via `ElementInternals` — use a real `<form>`, `md-button type="submit"`, and native `required` (§4.7) |
| Rich text | integrate a third-party editor; there is no `md-rich-text` |

### 2.1 Global switches — the complete set

All are attributes on `<html>` (or any ancestor; the nearest one wins).

```html
<html
  lang="en"
  dir="ltr"                  <!-- or rtl -->
  data-theme="dark"          <!-- omit for light -->
  data-density="-1"          <!-- -1 … -4; see below -->
  data-ripple="off"          <!-- default on -->
  data-shape-morph="off"     <!-- default on -->
>
```

**`data-density="0"` is inert.** No `[density="0"]` rule exists — density `0` is
simply the base values on `:root`, and a `0` rule would pin them onto every
element (reflected props write `density="0"` almost everywhere) and break global
inheritance. So the *overriding* range is `-1 … -4`. To escape an inherited rung
for one subtree, reset the scale directly:

```css
.opt-out-of-density { --md-sys-density-scale: 0; }
```

Per-component overrides beat the global one: a `density` prop, or
`ripple="off"` / `shape-morph="off"` on the element. **53 of the 57 top-level
components expose a `density` prop.** The four that don't: `md-divider`,
`md-ripple`, `md-sparkline`, `md-tabs`. (Nine sub-components also lack one —
they inherit density from the parent that owns their layout.)

---

## §3 — Install and bootstrap

```bash
npm install @awc-ui/core
```

**Register everything (recommended).** Two imports, once per app entry — one
defines every component, one loads the tokens. Both come from `@awc-ui/core`
itself, so this path needs no second package:

```ts
import { defineCustomElements } from '@awc-ui/core/loader';
import '@awc-ui/core/css/tokens.css';

defineCustomElements(window);
```

`@awc-ui/core/css/tokens.css` is the complete, self-contained token sheet —
light and dark colour roles, shape, elevation, motion, typescale, spacing and
z-index. It is the same set documented in §4.1.

**One-line alternative.** `@awc-ui/core/define` does both steps in a single
import. It loads the package's own token sheet, so it needs nothing else
installed:

```ts
import '@awc-ui/core/define'; // defines every component + loads the token sheet
```

`define` is client-only (it eval-guards `window`) and, because it imports CSS,
it needs a bundler. Never import it into a server graph.

**Per-component registration**, for size-sensitive bundles — load the token
sheet once yourself:

```ts
import '@awc-ui/core/css/tokens.css';
import '@awc-ui/core/components/md-button';
import '@awc-ui/core/components/md-text-field';
```

**Framework wrappers** — use these instead of raw elements; they handle
registration, typed props, and event binding. Below the version floor, drop to
the raw custom elements and the `loader` import above.

| Framework | Package | Requires |
|---|---|---|
| React / Next | `@awc-ui/react` | React 18+ |
| Angular | `@awc-ui/angular` (`AwcUiModule`) | Angular 17+ |
| Vue / Nuxt | `@awc-ui/vue` | Vue 3 |
| Svelte / SvelteKit | `@awc-ui/svelte` | Svelte 4+ |
| Plain HTML / Astro | `@awc-ui/core/loader` | — |

**SSR** — `@awc-ui/core/hydrate` renders Declarative Shadow DOM on the server.
`@awc-ui/react` ships matching client/server wrappers. Keep `define` and
`loader` out of the server graph; both are browser entries.

**Fonts** — components expect Roboto and Material Symbols Outlined to be
available. The library does **not** inject them. Every `icon="…"` prop renders a
Material Symbols glyph inside shadow DOM, so the font must be registered at the
**document** level (font registration crosses shadow boundaries; class rules do
not — the components declare the class rule inside their own roots):

```html
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined">
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Roboto:wght@400;500&display=swap">
```

To swap the whole library to a different Material Symbols cut, set
`--md-sys-icon-font-family` on `:root` and load the matching `@font-face`.

---

## §4 — Global configuration reference

### 4.1 The token system

All AWC UI styling resolves to design tokens. **Never hardcode hex colours,
pixel radii, shadows, or font stacks** — they break theming, dark mode, density
and RTL in one stroke. Every value below is a real custom property defined by
`@awc-ui/tokens`; you may read them, and you may override them.

#### Color roles

Light is the default; `[data-theme="dark"]` swaps the palette. Every role has a
matching `on-` role for content drawn on top of it.

| Token | Light | Dark | Typical usage |
|---|---|---|---|
| `--md-sys-color-primary` | `#6750A4` | `#D0BCFF` | Filled buttons, active states |
| `--md-sys-color-on-primary` | `#FFFFFF` | `#381E72` | Text/icons on primary |
| `--md-sys-color-primary-container` | `#EADDFF` | `#4F378B` | FAB, selected segments |
| `--md-sys-color-on-primary-container` | `#21005D` | `#EADDFF` | Text on primary-container |
| `--md-sys-color-secondary` | `#625B71` | `#CCC2DC` | Secondary accents |
| `--md-sys-color-secondary-container` | `#E8DEF8` | `#4A4458` | Tonal buttons, chips |
| `--md-sys-color-tertiary` | `#7D5260` | `#EFB8C8` | Tertiary accents |
| `--md-sys-color-tertiary-container` | `#FFD8E4` | `#633B48` | Tertiary surfaces |
| `--md-sys-color-error` | `#B3261E` | `#F2B8B5` | Error / destructive |
| `--md-sys-color-on-error` | `#FFFFFF` | `#601410` | Content on error |
| `--md-sys-color-error-container` | `#F9DEDC` | `#8C1D18` | Error surfaces |
| `--md-sys-color-surface` | `#FFFBFE` | `#1C1B1F` | Page / card background |
| `--md-sys-color-on-surface` | `#1C1B1F` | `#E6E1E5` | Body text |
| `--md-sys-color-surface-variant` | `#E7E0EC` | `#49454F` | Muted fills |
| `--md-sys-color-on-surface-variant` | `#49454F` | `#CAC4D0` | Secondary text, icons |
| `--md-sys-color-surface-container-lowest` | `#FFFFFF` | `#0F0D13` | Lowest surface tier |
| `--md-sys-color-surface-container-low` | `#F7F2FA` | `#1D1B20` | Card / elevated button bg |
| `--md-sys-color-surface-container` | `#F3EDF7` | `#211F26` | Default container tier |
| `--md-sys-color-surface-container-high` | `#ECE6F0` | `#2B2930` | Dialog / menu surfaces |
| `--md-sys-color-surface-container-highest` | `#E6E0E9` | `#36343B` | Highest surface tier |
| `--md-sys-color-outline` | `#79747E` | `#938F99` | Borders (3:1 contrast) |
| `--md-sys-color-outline-variant` | `#CAC4D0` | `#49454F` | Dividers (low contrast) |
| `--md-sys-color-inverse-surface` | `#313033` | `#E6E1E5` | Snackbar, inverse chips |
| `--md-sys-color-inverse-on-surface` | `#F4EFF4` | `#313033` | Content on inverse-surface |
| `--md-sys-color-scrim` | `#000000` | `#000000` | Modal scrims |

**Semantic status roles** — beyond the baseline M3 palette, the library adds
`success`, `warning` and `info`, each with `on-`, `-container` and
`on-…-container` companions, in both themes, AA-verified. Used by `md-chip`,
`md-badge`, `md-meter`, `md-status-dot`.

| Token | Light | Dark |
|---|---|---|
| `--md-sys-color-success` | `#2E6B4F` | `#9DD5B0` |
| `--md-sys-color-success-container` | `#B8F0CE` | `#14512F` |
| `--md-sys-color-warning` | `#7A5900` | `#EFC148` |
| `--md-sys-color-warning-container` | `#FFDF9B` | `#5C4200` |
| `--md-sys-color-info` | `#38608F` | `#A2C9FE` |
| `--md-sys-color-info-container` | `#D3E4FF` | `#1E4975` |

#### Shape tokens

| Token | Value | Typical usage |
|---|---|---|
| `--md-sys-shape-corner-none` | `0px` | Square edges |
| `--md-sys-shape-corner-extra-small` | `4px` | Snackbar, small chips |
| `--md-sys-shape-corner-small` | `8px` | Cards (outlined), small surfaces |
| `--md-sys-shape-corner-medium` | `12px` | Cards (default), inputs |
| `--md-sys-shape-corner-large` | `16px` | Dialogs, large cards |
| `--md-sys-shape-corner-extra-large` | `28px` | Bottom sheets |
| `--md-sys-shape-corner-full` | `9999px` | Buttons, chips, FAB |

Partial-corner variants also exist for surfaces that meet an edge:
`--md-sys-shape-corner-extra-small-top`, `-large-top`, `-large-end`,
`-extra-large-top`. Their values are four-value `border-radius` shorthands
(e.g. `16px 16px 0px 0px`), so assign them to `border-radius`, not to a single
corner.

#### Elevation tokens

`-0` is the keyword `none`; `-1` through `-5` are complete `box-shadow` values,
and those five are **re-declared with deeper shadows under `[data-theme="dark"]`**
— so always use the token rather than copying its value.

| Token | When |
|---|---|
| `--md-sys-elevation-0` | `none` — resting cards, flat surfaces |
| `--md-sys-elevation-1` | Elevated buttons and cards at rest |
| `--md-sys-elevation-2` | Hover bump |
| `--md-sys-elevation-3` | FAB, menus, dialogs at rest |
| `--md-sys-elevation-4` – `-5` | Reserved for the most prominent surfaces |

#### Motion tokens

Durations come in four families of four: `short1…4` (50/100/150/200ms),
`medium1…4` (250/300/350/400ms), `long1…4` (450/500/550/600ms), and
`extra-long1…4` (700/800/900/1000ms).

| Token | Value | When |
|---|---|---|
| `--md-sys-motion-duration-short2` | `100ms` | Buttons, ripples, state layers |
| `--md-sys-motion-duration-medium2` | `300ms` | Dialogs, sheets, menus |
| `--md-sys-motion-duration-long2` | `500ms` | Large surface transitions |
| `--md-sys-motion-duration-extra-long1` | `700ms` | Ambient / chart entrances |
| `--md-sys-motion-easing-standard` | `cubic-bezier(0.2, 0, 0, 1)` | Small utility transitions |
| `--md-sys-motion-easing-standard-accelerate` | `cubic-bezier(0.3, 0, 1, 1)` | Exits |
| `--md-sys-motion-easing-standard-decelerate` | `cubic-bezier(0, 0, 0, 1)` | Entrances |
| `--md-sys-motion-easing-emphasized` | `cubic-bezier(0.2, 0, 0, 1)` | Expressive transitions |
| `--md-sys-motion-easing-emphasized-accelerate` | `cubic-bezier(0.3, 0, 0.8, 0.15)` | Expressive exits |
| `--md-sys-motion-easing-emphasized-decelerate` | `cubic-bezier(0.05, 0.7, 0.1, 1)` | Expressive entrances |
| `--md-sys-motion-easing-linear` | `linear` | Progress, indeterminate loops |

> `--md-sys-motion-easing-emphasized` deliberately equals the standard curve:
> the full M3 emphasized curve is a two-phase path interpolator that CSS cannot
> express. The accelerate and decelerate halves *are* expressible, and are the
> ones to reach for.

MD3 Expressive also ships spring pairs, each an easing plus its natural
duration: `--md-sys-motion-spring-{spatial,effects}-{fast,default,slow}-easing`
and `…-duration`. Spatial = position/size/shape; effects = colour/opacity.

#### State-layer opacities

| Token | Value |
|---|---|
| `--md-sys-state-hover-state-layer-opacity` | `0.08` |
| `--md-sys-state-focus-state-layer-opacity` | `0.12` |
| `--md-sys-state-pressed-state-layer-opacity` | `0.12` |
| `--md-sys-state-dragged-state-layer-opacity` | `0.16` |
| `--md-sys-state-disabled-container-opacity` | `0.12` |
| `--md-sys-state-disabled-content-opacity` | `0.38` |

#### Typography, spacing and layering

- **Typescale** — `--md-sys-typescale-<role>-<size>-*` for
  `display`/`headline`/`title`/`label`/`body` × `large`/`medium`/`small`. Each
  role exposes `-font-family`, `-font-size`, `-line-height`, `-font-weight`,
  `-letter-spacing`, plus a `-font` shorthand
  (e.g. `--md-sys-typescale-headline-medium-font: 400 28px/36px Roboto, sans-serif`).
  Use the shorthand on the `font` property for headings you write yourself.
- **Spacing** — a 4px scale that tightens with density:
  `--md-sys-spacing-inset-{xs,sm,md,lg,xl}` (internal padding, 4/8/12/16/24px)
  and `--md-sys-spacing-gap-{xs,sm,md,lg}` (between siblings, 4/8/12/16px), plus
  `--md-sys-spacing-row-height` (`56px` at density 0).
- **Layering** — `--md-sys-z-index-app-bar` (100), `-navigation` (200),
  `-bottom-sheet` (300), `-popup` (1000), `-dialog-scrim` (1001), `-tooltip`
  (1500), `-snackbar` (2000). Use these instead of inventing z-indexes, or your
  overlay will land under a menu.

### 4.2 Theming and rebranding

To rebrand, redefine the role variables **after** the tokens stylesheet — both
themes, or dark mode inherits your light brand colour:

```css
:root {
  --md-sys-color-primary: #00629E;
  --md-sys-color-on-primary: #FFFFFF;
  --md-sys-color-primary-container: #CFE5FF;
  --md-sys-color-on-primary-container: #001D33;
}
[data-theme="dark"] {
  --md-sys-color-primary: #9BCBFF;
  --md-sys-color-on-primary: #003354;
  --md-sys-color-primary-container: #004A78;
  --md-sys-color-on-primary-container: #CFE5FF;
}
```

Per-component knobs are `--md-<component>-*` custom properties, listed in each
manual's Theming section (`--md-button-container-color`,
`--md-card-container-shape`, …). Prefer those over `::part()`, and prefer
`::part()` over reaching into shadow internals, which are unstable and will
break on any release.

**Overriding a colour role forfeits the library's contrast testing.** Re-verify
AA (4.5:1 text, 3:1 borders and dividers) after any palette change. The Theme
Generator at <https://awc-ui.dev/theme-generator> takes a seed colour, emits both
palettes as `--md-sys-color-*` overrides, and runs the WCAG checks live — use it
rather than hand-picking container and `on-` pairs.

### 4.3 Density

`data-density` steps `-1 → -4`; each rung trims ~4px of padding and touch
target, driving `--md-sys-density-scale` and the spacing tokens. `-4` is the
floor. Set it globally, override locally with the `density` prop. Do not go
below `-2` on touch-primary surfaces — you will break the 48px target.

Two details that bite:

- **`density="0"` does nothing** — see §2 for why, and for the
  `--md-sys-density-scale: 0` escape hatch.
- **`md-table` accepts two vocabularies**: the semantic `compact` / `standard` /
  `comfortable` (row heights 36 / 52 / 60px) *and* the numeric rungs. They
  compose — `density="compact"` inside a `data-density="-2"` region condenses
  further.

### 4.4 Dark mode

Set `data-theme="dark"` on `<html>` (or any ancestor — the nearest wins). The
tokens swap automatically and inherit across every shadow boundary; no
per-component code. To mirror the OS, read `prefers-color-scheme` and write the
attribute **before first paint**, or the page flashes light.

### 4.5 RTL

Layout is written with CSS logical properties, so it flips with `dir="rtl"`
without extra work. Two things still need you:

- **Directional glyphs do not flip.** Material Symbols are not auto-mirrored.
  `md-button` has a `mirror-icon` prop that mirrors its own leading/trailing
  glyph — set it on buttons using arrows, chevrons, `send`, `reply`, and leave
  it off for `add`, `search`, `favorite`. **`mirror-icon` exists only on
  `md-button`.** Everywhere else — `md-icon-button icon="…"`, `md-list-item`
  leading/trailing icons, `md-app-bar leading-icon` — swap the glyph name
  yourself (`arrow_back` ↔ `arrow_forward`).
- **Icon props you supply yourself** — e.g. `md-transfer-list`'s
  `move-right-icon` / `move-left-icon` / `move-all-*-icon` — must be swapped by
  you when the direction flips.

Never write physical CSS (`margin-left`, `padding-right`, `left`) around these
components. Use `margin-inline-start`, `padding-inline-end`, `inset-inline-end`.

### 4.6 Internationalization

Components are **i18n-engine-agnostic by design**. Every user-visible string is
either slotted content or a prop. Localize in the consumer layer: resolve your
dictionary to plain strings, then pass them in. Do not add a translation engine
inside a component. `locale` props exist only where a component computes an
`Intl`-formatted value itself: `md-date-picker`, `md-number-field`,
`md-meter`, `md-dialog`, and the charts (`md-bar-chart`, `md-line-chart`,
`md-area-chart`, `md-pie-chart`). `md-time-picker` has no
`locale` prop — it takes `format="12h" | "24h"` instead.

Templated strings keep their placeholder tokens when translated — translate
around the braces, don't remove them:

```html
<md-transfer-list count-template="{checked} / {total} ausgewählt"></md-transfer-list>
```

Other templated props: `md-autocomplete status-template`, `md-otp-field
cell-label-template`. Default prop values are English (`Search`, `Dismiss`,
`No results`, `Move selected to target`, …) — every one of them needs
translating in a localized app.

### 4.7 Forms and validation

Fourteen components are form-associated via `ElementInternals`, so they
participate in `FormData` and constraint validation like native controls:

`md-text-field` · `md-number-field` · `md-otp-field` · `md-select` ·
`md-multi-select` · `md-autocomplete` · `md-checkbox` · `md-radio` ·
`md-switch` · `md-slider` · `md-rating` · `md-date-picker` · `md-time-picker` ·
`md-button`

Rules:

- Use a real `<form>`. `md-button type="submit"` calls `form.requestSubmit()`
  (not `submit()`), so the `submit` event fires **and** built-in constraint
  validation runs. `required` genuinely blocks submit.
  `md-button type="reset"` calls `form.reset()`.
- Give every control a `name`, or it will not appear in `FormData`.
- Do **not** add hidden `<input>`s to mirror values — that's the old pattern and
  it double-submits.
- Validity changes are announced on a `mdValidityChange` event on the control.
  Error presentation is `error` + `error-text` on the field.
- Boolean state props differ by control — `md-checkbox` uses `checked`,
  `md-switch` uses **`selected`**, `md-select-option` uses `selected`. Check the
  manual; guessing `checked` on a switch silently does nothing.

---

## §5 — Component decision matrix

Route by **need**, not by name. If the need isn't listed, find the closest row
and read that component's `When NOT to use`.

### 5.1 Actions

| Need | Use | Don't use |
|---|---|---|
| Discrete labelled action | `md-button` | `md-chip`, raw `<button>` |
| Icon-only action | `md-icon-button` | `md-button` with no label |
| A destructive action | `md-button` + `md-dialog` to confirm | an unconfirmed `filled` button |
| The single most prominent screen action (mobile) | `md-fab` | a second `filled` `md-button` |
| One prominent action that expands to several | `md-fab-menu` + `md-fab-menu-item` | a stack of FABs |
| Primary action + variants of it | `md-split-button` | button + separate menu |
| 2–5 related actions as one unit | `md-button-group` | loose adjacent buttons |
| Mutually exclusive view/mode switch | `md-segmented-button-set` + `md-segmented-button` | radio buttons, tabs |
| Overflow / contextual actions | `md-menu` + `md-menu-item` | a row of text buttons |

### 5.2 Text input

| Need | Use | Don't use |
|---|---|---|
| Any single-line or multi-line text entry | `md-text-field` | raw `<input>` |
| A number with steppers and locale formatting | `md-number-field` | `md-text-field type="number"` |
| A one-time code / PIN | `md-otp-field` | a row of text fields |
| Text entry with suggestions | `md-autocomplete` | `md-select` |
| Site/app-wide search with a results surface | `md-search` | `md-text-field` with an icon |

### 5.3 Selection

| Need | Use | Don't use |
|---|---|---|
| One of many, from a list | `md-select` + `md-select-option` | radio group over ~7 options |
| One of few (2–5), all visible | `md-radio` | `md-select` |
| Several of many | `md-multi-select` | many `md-checkbox`es |
| Several of few, all visible | `md-checkbox` | `md-multi-select` |
| Instant on/off setting | `md-switch` | `md-checkbox` |
| A value in a numeric range | `md-slider` | `md-text-field type=number` |
| Subjective score | `md-rating` | slider |
| A color | `md-color-picker` | `<input type=color>` |
| Assign a subset from a bounded pool, side by side | `md-transfer-list` | two lists + buttons |
| Filter / attribute / removable entry | `md-chip` | small buttons |
| A date | `md-date-picker` | three selects |
| A time | `md-time-picker` | text field |

### 5.4 Navigation

| Need | Use | Don't use |
|---|---|---|
| Top-level destinations, mobile | `md-navigation-bar` + `md-navigation-tab` | tabs |
| Top-level destinations, desktop | `md-navigation-rail` + `md-navigation-rail-tab` | bottom bar |
| App header: title, actions, search | `md-app-bar` | a custom `<header>` |
| A dense action strip | `md-toolbar` | app bar |
| Sibling views **within** one screen | `md-tabs` + `md-tab` + `md-tab-panels` + `md-tab-panel` | navigation bar |
| Hierarchy / where-am-I | `md-breadcrumbs` + `md-breadcrumb-item` | text links |
| A linear multi-step flow | `md-stepper` + `md-step` | tabs |
| Contextual popup actions | `md-menu` + `md-menu-item`, `md-menu-item-group`, `md-sub-menu-item` | dialog |
| Hierarchical command menu (File → Export → PDF) | `md-menu` + `md-sub-menu-item` | nested dialogs |

### 5.5 Containment and feedback

| Need | Use | Don't use |
|---|---|---|
| Group related content | `md-card` | a bare `<div>` with a border |
| Blocking decision or focused task | `md-dialog` | a new page |
| Critical error the user must acknowledge | `md-dialog` | `md-snackbar` |
| Supplementary content from the bottom (mobile) | `md-bottom-sheet` | dialog |
| Supplementary content from the side (desktop) | `md-side-sheet` | dialog |
| Brief confirmation of an action, optionally undoable | `md-snackbar` | dialog, alert |
| Explain a control on hover/focus | `md-tooltip` | a dialog or inline hint |
| Progressive disclosure of sections | `md-accordion` + `md-accordion-item` | tabs |
| Visual separation | `md-divider` | a styled `<hr>` |
| A vertical set of records | `md-list` + `md-list-item` | a table |
| Determinate/indeterminate progress | `md-progress-indicator` | spinner GIF |
| Brand-consistent page/content loading | `md-loading-indicator` | custom spinner |
| Content-shaped loading placeholder | `md-skeleton` | a spinner over the whole page |
| Count or status on an element | `md-badge` | superscript text |
| Compact status dot | `md-status-dot` | a colored emoji |
| Read-only value within a known range (quota, battery) | `md-meter` | `md-progress-indicator` |
| A person or entity image/initials | `md-avatar` | a raw `<img>` |
| Touch feedback inside a custom control | `md-ripple` | custom CSS animation |

### 5.6 Data

| Need | Use | Don't use |
|---|---|---|
| Any table | `md-table-container` wrapping `md-table`, with `-head`/`-body`/`-row`/`-cell`/`-foot` inside the table and `-toolbar`/`-pagination` beside it in the container (§7.1) | a native `<table>` |
| Sorting, selection, paging on that table | the same parts — `md-table` carries the STATE (`sort-by`, `sort-order`, `selection`, `row-offset`, `row-count`, `loading`) and emits events; you own the data and do the actual sorting/paging | expecting it to sort an array for you |
| Hierarchy / reporting lines | `md-organization-chart` | nested lists |
| Compare categories | `md-bar-chart` | pie chart |
| Trend over time | `md-line-chart` | bar chart |
| Trend with cumulative volume | `md-area-chart` | line chart |
| Parts of a whole (≤ ~6 slices) | `md-pie-chart` | bar chart |
| Inline micro-trend in a cell or card | `md-sparkline` | a full chart |

> **There is no data-driven table component.** `md-table` is composable: you
> render the rows. It tracks and announces sort, selection and pagination state
> and emits events when the user changes them, but the sorting, filtering and
> slicing of your data is yours to perform. Render rows from your own array in
> response to those events.

### 5.7 Choosing the variant

The matrix picks the component; this picks its shape. Every value below is a
real enum member — anything not listed here is not a valid value.

| Component | Prop | Values, and when |
|---|---|---|
| `md-button` | `variant` | `filled` the one primary action · `tonal` a strong secondary · `outlined` secondary, and the safe choice for a destructive action behind a confirm · `text` low emphasis, dialog Cancel · `elevated` when it sits on a busy or coloured background (default `filled`) |
| `md-button` / `md-icon-button` / `md-button-group` | `size` | `xs` `sm` `md` `lg` `xl` — default `sm`; go `md`/`lg` for consumer CTAs, `xs`/`sm` for dense admin UI |
| `md-icon-button` | `variant` | `standard` (default) · `filled` · `tonal` · `outlined` |
| `md-button-group` | `variant` | `standard` spaced · `connected` fused into one bar |
| `md-fab` | `size` | `standard` (default) · `medium` · `large` |
| `md-fab` | `variant` | `primary-container` (default) · `secondary-container` · `tertiary-container` · `surface` · `primary` · `secondary` · `tertiary` |
| `md-card` | `variant` | `filled` for a group of comparable items · `elevated` (default) for a hero or featured item · `outlined` for a settings or form section |
| `md-text-field` / `md-select` | `variant` | `outlined` for forms on a surface · `filled` for dense or tinted layouts (`md-text-field` defaults to `filled`, `md-select` to `outlined`) — pick one and use it for every field on the screen |
| `md-text-field` | `type` | any native input type: `password`, `email`, `tel`, `url`, `search`, … (default `text`) |
| `md-text-field` | `multiline` | `"auto-grow"` grows with content · `"fixed"` with `rows` for a fixed comment box · `false` (default) single line |
| `md-search` | `variant` | `contained` (default) · `divided` |
| `md-app-bar` | `variant` | `small` (default) · `medium` · `large` for a prominent headline · `search` for a bar that hosts a field |
| `md-chip` | `variant` | `assist` (default) · `filter` for toggleable facets · `input` for user-entered removable values · `suggestion` |
| `md-chip` | `appearance` | `outlined` (default) · `filled` · `elevated` |
| `md-badge` | `variant` | `small` a bare dot · `large` (default) a count |
| `md-tooltip` | `variant` | `plain` (default) a short label on an icon control · `rich` an explanatory popover that may hold a link or action |
| `md-divider` | — | **no `variant`** — use the booleans `inset`, `inset-start`, `inset-end` |
| `md-side-sheet` | `variant` | `standard` coexists with page content · `modal` overlays with a scrim |
| `md-bottom-sheet` | `variant` | `standard` (default) · `detached` floating above the edge |
| `md-dialog` | `fullscreen` | boolean — a full-screen dialog for a long mobile task |
| `md-date-picker` | `variant` | `modal-input` (default) calendar plus a typed field · `modal` calendar only · `docked` inline, anchored to the field |
| `md-time-picker` | `variant` | `dial` · `input` (default) |
| `md-progress-indicator` | `variant` | `linear` (default) · `circular`; add `indeterminate` when the total is unknown |
| `md-list-item` | `lines` | `1` · `2` · `3` — must match how much supporting text you pass |
| `md-navigation-bar` | — | 3–5 destinations. Fewer than three: use `md-tabs`. More than five: a rail or a menu |
| `md-navigation-rail` | — | 3–7 destinations; cap the overflow with `max-visible` |

### 5.8 Not in the library

Rich text editor · file upload/dropzone · calendar/scheduler view · map ·
toast stack manager (use `md-snackbar` and manage the queue yourself) ·
data grid with virtualized columns. If the user needs one, say so plainly and
integrate a third-party component styled with the MD3 tokens.

**There is no `md-grid`, no `md-data-table`, no `md-layout`, no `md-icon`.**
If a tag is not listed in §6, it does not exist — do not emit it.

---

## §6 — Component inventory

**Every component has exactly one manual, and it is the readme.md in its own
source folder:**

```
./packages/core/src/components/<tag>/readme.md
```

e.g. [`md-select`](./packages/core/src/components/md-select/readme.md),
[`md-button`](./packages/core/src/components/md-button/readme.md).

**Load that file before you use the component.** There is no second, shorter
summary to rely on — this readme is the single source, so anything you do not
read there, you do not know. Each one carries When-to-use, a Do/Don't table
from M3, copy-paste patterns, an anti-patterns table, and the theming surface.

Work through them one at a time: pick the component from the decision matrix
(§5), load its readme, write that component's markup, then move to the next.

There are 81 manuals for 57 components: 24 of them document sub-components that
are only valid inside a parent (a table cell, a tab panel, a select option).
Every sub-component manual names its parent in the first line, and §7 below
summarises the nesting.

`status` in each manual's `llm:meta` block is one of:

- **`md3-mapped`** — has a Material Design 3 guidelines page; the Do/Don't is
  sourced from it.
- **`custom`** — an addition to MD3; guidance is derived house rules.
- **`sub-component`** — only valid inside a specific parent.

| Category | Components |
|---|---|
| Actions | `md-button` `md-icon-button` `md-fab` `md-fab-menu` `md-fab-menu-item` `md-split-button` `md-button-group` `md-segmented-button` `md-segmented-button-set` |
| Text input | `md-text-field` `md-number-field` `md-otp-field` `md-autocomplete` `md-search` |
| Selection | `md-select` `md-select-option` `md-multi-select` `md-checkbox` `md-radio` `md-switch` `md-slider` `md-rating` `md-color-picker` `md-transfer-list` `md-chip` |
| Pickers | `md-date-picker` `md-time-picker` |
| Navigation | `md-app-bar` `md-toolbar` `md-navigation-bar` `md-navigation-tab` `md-navigation-rail` `md-navigation-rail-tab` `md-tabs` `md-tab` `md-tab-panels` `md-tab-panel` `md-breadcrumbs` `md-breadcrumb-item` `md-menu` `md-menu-item` `md-menu-item-group` `md-sub-menu-item` `md-stepper` `md-step` |
| Containment | `md-card` `md-dialog` `md-bottom-sheet` `md-side-sheet` `md-snackbar` `md-tooltip` `md-accordion` `md-accordion-item` `md-divider` `md-list` `md-list-item` |
| Data | `md-table` `md-table-container` `md-table-head` `md-table-body` `md-table-row` `md-table-cell` `md-table-foot` `md-table-toolbar` `md-table-pagination` `md-table-sort-label` `md-table-expand-toggle` `md-organization-chart` |
| Charts | `md-bar-chart` `md-line-chart` `md-area-chart` `md-pie-chart` `md-sparkline` |
| Status & feedback | `md-progress-indicator` `md-loading-indicator` `md-skeleton` `md-badge` `md-status-dot` `md-meter` `md-avatar` `md-ripple` |

---

## §7 — Composition rules

### 7.1 What nests inside what

A sub-component is only valid inside its parent. Putting one anywhere else
produces an unstyled, unregistered-looking element with no keyboard behaviour,
because the parent is what wires roving tabindex, ARIA ids and selection.

| Parent | Children it manages |
|---|---|
| `md-button-group` | `md-button`, `md-icon-button` |
| `md-segmented-button-set` | `md-segmented-button` |
| `md-fab-menu` | `md-fab-menu-item` (anchored to an `md-fab` via `anchor="<id>"`) |
| `md-menu` | `md-menu-item`, `md-sub-menu-item`, `md-menu-item-group` — **not** `md-divider`; separate rows with `md-menu-item`'s own `divider` (or `gap`) prop |
| `md-menu-item-group` | `md-menu-item` |
| `md-sub-menu-item` | a nested `md-menu` in `slot="submenu"` — the items go in *that* menu. There is no default slot, so anything else you nest renders nothing |
| `md-select`, `md-multi-select`, `md-autocomplete` | `md-select-option` |
| `md-list` | `md-list-item`, `md-divider` |
| `md-tabs` | `md-tab` |
| `md-tab-panels` | `md-tab-panel` (one per tab, in tab order) |
| `md-navigation-bar` | `md-navigation-tab` |
| `md-navigation-rail` | `md-navigation-rail-tab`, plus an `md-fab` in `slot="fab"` |
| `md-accordion` | `md-accordion-item` |
| `md-stepper` | `md-step` (horizontal steppers also take `slot="content"`) |
| `md-breadcrumbs` | `md-breadcrumb-item` |
| `md-table-container` | `md-table` — **it wraps the table, not the other way round** — plus `md-table-toolbar` in `slot="top"` and `md-table-pagination` in `slot="bottom"`, which sit outside the scroll region |
| `md-table` | `md-table-head`, `md-table-body`, `md-table-foot` (and bare `md-table-row`). It does **not** accept the container, toolbar or pagination |
| `md-table-head` / `-body` / `-foot` | `md-table-row` |
| `md-table-row` | `md-table-cell`, plus `md-table-expand-toggle` for an expandable row |
| `md-table-cell` | `md-table-sort-label` in a header cell |
| `md-tooltip` | **its trigger** — the tooltip wraps the element it describes in its default slot |
| `md-dialog` | body content in the default slot; `md-button` in `slot="actions"` |
| `md-bottom-sheet` / `md-side-sheet` | content in the default slot; `md-button` in `slot="actions"`; headline in `slot="headline"` |
| `md-app-bar` | `md-icon-button` in `slot="leading"` and `slot="trailing"`; `md-menu` for overflow; a field in `slot="search"` on `variant="search"` |
| `md-toolbar` | `md-icon-button`, `md-button`, `md-button-group`; an `md-fab` in `slot="fab"`; `slot="leading"` / `slot="trailing"` for the end clusters |

### 7.2 Pairs that belong together

These don't nest — they sit next to each other in a working flow. Reaching for
one usually means you want the other.

| This | Goes with | Why |
|---|---|---|
| `md-icon-button` | `md-tooltip` | The tooltip supplies the visible meaning the icon lacks |
| `md-button` (`soft-disabled`) | `md-tooltip` | Explains *why* the action is unavailable |
| `md-fab` | `md-fab-menu` | The FAB is the menu's anchor |
| `md-split-button` | `md-menu` | The trailing half opens it |
| `md-card` | `md-button`, `md-icon-button`, `md-divider` | Footer actions, corner action, internal sections |
| `md-list-item` | `md-checkbox`, `md-switch`, `md-icon-button` | Trailing controls in a selectable or settings row |
| `md-bottom-sheet` / `md-side-sheet` | `md-list` | Action menus and filter panels inside the sheet |
| `md-search` | `md-list`, `md-avatar`, `md-icon-button` | Results in the panel; account and voice/filter affordances in the trailing slot |
| `md-date-picker` | `md-time-picker` | Date + time row for booking and scheduling forms |
| `md-time-picker` | `md-button` | The trigger, when `hide-trigger` is set. The picker **is** its own dialog — don't nest it in another one |
| `md-text-field` | `md-button` | Submit / cancel in the form footer |
| `md-multi-select` / `md-autocomplete` | `md-text-field`, `md-menu`, `md-chip` | The field is the trigger (and inherits its variant, density and error state), the menu is the option surface, chips are the selected values |
| `md-autocomplete` | `md-progress-indicator` | The loading row while suggestions are fetched |
| `md-transfer-list` | `md-checkbox`, `md-text-field`, `md-icon-button` | Per-row select, per-side search, mover controls |
| `md-number-field` | `md-text-field` hooks, `md-icon-button` | It *is* an `md-text-field` internally — every `--md-text-field-*` custom property passes through — and its steppers are `md-icon-button`s |
| `md-otp-field` | `md-button` | Verify action (`auto-submit` covers the no-button flow) |
| Any chart | `md-card` | Charts belong on a dashboard tile |
| `md-line-chart` | `md-segmented-button-set` | Period picker (1W / 1M / 1Y) driving the range |
| `md-sparkline` | `md-list-item`, `md-table-cell` | Trend column beside a value |
| `md-skeleton` | `md-card`, `md-list` | Render N placeholders in the real layout while fetching |
| `md-meter` | `md-chip`, `md-card` | Same semantic status colour on both; quota and usage summaries live on a card |
| `md-color-picker` | `md-text-field`, `md-button` | Label and helper text beside it in a form; save / cancel in the surrounding popover or dialog |
| `md-rating` | `md-text-field`, `md-card` | A rating row in a review form; aggregate scores on a review card |
| `md-accordion` | `md-divider` | Optional inner dividers inside long item content |
| `md-stepper` | `md-button` | Next / back / submit adjacent to the stepper |

### 7.3 Nesting that is always wrong

- A dialog opened from inside a dialog. Use `md-stepper` inside **one**
  `md-dialog`.
- A component inside a native interactive element (`<button>`, `<a>`) — it
  nests interactive controls and destroys the accessibility tree. Use the
  component's own `href` / `type` props.
- `md-tabs` used for top-level app navigation. Tabs switch sibling views of the
  same data; destinations are `md-navigation-bar` / `md-navigation-rail`.

---

## §8 — Page recipes

Complete, runnable screens. Each renders as-is once the components are
registered and the token sheet and font links from §3 are loaded — no
placeholder identifiers, no helper functions to write.

### 8.1 Login screen

`<form>` is load-bearing: it is what makes `required` block submit and what
`type="submit"` calls `requestSubmit()` on.

```html
<main style="display: grid; place-items: center; min-block-size: 100dvh; padding: 24px;">
  <form id="login-form" style="inline-size: min(420px, 100%);">
    <md-card variant="elevated" style="padding: 32px; display: flex; flex-direction: column; gap: 20px;">
      <h1 style="margin: 0; font: var(--md-sys-typescale-headline-medium-font);">Sign in</h1>

      <md-text-field
        variant="outlined"
        label="Email"
        type="email"
        name="email"
        autocomplete="username"
        required
      ></md-text-field>

      <md-text-field
        variant="outlined"
        label="Password"
        type="password"
        name="password"
        autocomplete="current-password"
        password-toggle="internal"
        required
      ></md-text-field>

      <md-button variant="filled" type="submit" full-width>Sign in</md-button>
      <md-button variant="text" href="/forgot-password">Forgot password?</md-button>
    </md-card>
  </form>
</main>

<script type="module">
  document.getElementById('login-form').addEventListener('submit', (e) => {
    e.preventDefault();
    const data = new FormData(e.currentTarget);
    console.log(data.get('email'), data.get('password'));
  });
</script>
```

### 8.2 Settings page (mobile)

Top app bar + grouped rows of instant-apply switches. `md-switch` uses
**`selected`**, not `checked`. The rows are `type="text"` (non-interactive), so
the switch is the only control — one tab stop per setting.

```html
<md-app-bar variant="small" headline="Settings">
  <md-icon-button slot="leading" icon="arrow_back" aria-label="Back"></md-icon-button>
</md-app-bar>

<main style="padding: 16px; display: flex; flex-direction: column; gap: 16px;">
  <md-card variant="outlined">
    <md-list>
      <md-list-item headline="Notifications" supporting-text="Push, email, in-app" lines="2">
        <md-switch slot="trailing" selected aria-label="Enable notifications" data-setting="notifications"></md-switch>
      </md-list-item>
      <md-divider></md-divider>
      <md-list-item headline="Dark mode" supporting-text="Match system" lines="2">
        <md-switch slot="trailing" aria-label="Enable dark mode" data-setting="dark"></md-switch>
      </md-list-item>
      <md-divider></md-divider>
      <md-list-item headline="Sync over cellular">
        <md-switch slot="trailing" selected aria-label="Sync over cellular" data-setting="cellular"></md-switch>
      </md-list-item>
    </md-list>
  </md-card>
</main>

<md-snackbar id="settings-toast" message="Setting saved"></md-snackbar>

<script type="module">
  const toast = document.getElementById('settings-toast');
  document.querySelectorAll('md-switch[data-setting]').forEach((sw) => {
    sw.addEventListener('mdChange', (e) => {
      if (sw.dataset.setting === 'dark') {
        document.documentElement.setAttribute('data-theme', e.detail.selected ? 'dark' : 'light');
      }
      toast.show();
    });
  });
</script>
```

### 8.3 Settings form (deferred save, with validation)

When settings are saved on submit rather than applied instantly, use a real
form. `required` blocks the submit; every control needs a `name` to reach
`FormData`.

```html
<form id="profile-form" style="max-inline-size: 560px; margin: 24px auto; padding: 0 16px;">
  <md-card variant="outlined" style="padding: 24px; display: flex; flex-direction: column; gap: 20px;">
    <h2 style="margin: 0; font: var(--md-sys-typescale-title-large-font);">Profile</h2>

    <md-text-field
      variant="outlined"
      label="Display name"
      name="displayName"
      required
      supporting-text="Shown on your public profile"
    ></md-text-field>

    <md-select variant="outlined" label="Language" name="language" value="en" required>
      <md-select-option value="en" label="English"></md-select-option>
      <md-select-option value="de" label="Deutsch"></md-select-option>
      <md-select-option value="ar" label="العربية"></md-select-option>
    </md-select>

    <!-- md-checkbox has NO label slot. It is a labelable, form-associated
         element: wrap it in a native <label> (which names it AND forwards
         clicks), or give the host an aria-label. Text between the tags is
         NOT rendered. -->
    <label style="display: inline-flex; align-items: center; gap: 12px; cursor: pointer;">
      <md-checkbox name="newsletter" value="yes" supporting-text="Monthly, no more"></md-checkbox>
      <span>Send me product news</span>
    </label>

    <div style="display: flex; gap: 8px; justify-content: flex-end;">
      <md-button variant="text" type="reset">Reset</md-button>
      <md-button variant="filled" type="submit">Save changes</md-button>
    </div>
  </md-card>
</form>

<md-snackbar id="saved-toast" message="Changes saved" action="Undo"></md-snackbar>

<script type="module">
  const form = document.getElementById('profile-form');
  const toast = document.getElementById('saved-toast');

  form.addEventListener('submit', (e) => {
    e.preventDefault();
    const data = Object.fromEntries(new FormData(form));
    console.log(data); // { displayName, language, newsletter? }
    toast.show();
  });

  toast.addEventListener('mdAction', () => form.reset());
</script>
```

### 8.4 Dashboard with a FAB

```html
<md-app-bar variant="medium" headline="Inbox">
  <md-icon-button slot="trailing" icon="search" aria-label="Search"></md-icon-button>
  <md-icon-button slot="trailing" icon="filter_list" aria-label="Filter"></md-icon-button>
</md-app-bar>

<main style="padding: 16px; display: grid; gap: 12px; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));">
  <md-card variant="filled" interactive style="padding: 16px;">
    <strong>Acme contract</strong>
    <p style="margin: 4px 0 0; color: var(--md-sys-color-on-surface-variant);">Renewal due in 5 days</p>
  </md-card>
  <md-card variant="filled" interactive style="padding: 16px;">
    <strong>Q4 report draft</strong>
    <p style="margin: 4px 0 0; color: var(--md-sys-color-on-surface-variant);">Shared by Alex</p>
  </md-card>
</main>

<md-fab
  icon="add"
  aria-label="New item"
  style="position: fixed; inset-block-end: 16px; inset-inline-end: 16px; z-index: var(--md-sys-z-index-navigation);"
></md-fab>
```

`inset-inline-end` (not `right`) is what keeps the FAB in the correct corner
under `dir="rtl"`.

### 8.5 Destructive confirmation dialog

`md-dialog` traps focus and returns it to the trigger on close — do not add your
own focus management. The error colouring goes through the button's own custom
properties, never a hex.

```html
<md-button id="open-delete" variant="outlined">Delete account</md-button>

<md-dialog id="confirm-delete" headline="Delete account?" icon="warning">
  <p style="margin: 0;">
    This will permanently delete your account and all associated data.
    This action cannot be undone.
  </p>
  <md-button id="cancel-delete" slot="actions" variant="text">Cancel</md-button>
  <md-button
    id="do-delete"
    slot="actions"
    variant="filled"
    style="--md-button-container-color: var(--md-sys-color-error);
           --md-button-label-color: var(--md-sys-color-on-error);"
  >Delete</md-button>
</md-dialog>

<script type="module">
  const dialog = document.getElementById('confirm-delete');
  document.getElementById('open-delete').addEventListener('mdClick', () => dialog.show());
  document.getElementById('cancel-delete').addEventListener('mdClick', () => dialog.close());
  document.getElementById('do-delete').addEventListener('mdClick', () => {
    dialog.close();
    // perform the deletion
  });
</script>
```

If you omit `slot="actions"` entirely, `md-dialog` renders its own Cancel / OK
pair (labels via `cancel-label` / `ok-label`) and closes itself.

### 8.6 Tabbed content page

`md-tab-panels` finds the nearest preceding `md-tabs` (or the one named by
`for`), follows its `mdTabChange`, and wires `aria-controls` /
`aria-labelledby` both ways. **No JavaScript is required**, and `md-tab` has no
`value` or `selected` prop — selection lives on `md-tabs` as `active-tab-index`.

```html
<md-tabs id="profile-tabs" aria-label="Profile sections" active-tab-index="0">
  <md-tab label="Posts"></md-tab>
  <md-tab label="Replies"></md-tab>
  <md-tab label="Likes" badge="3"></md-tab>
</md-tabs>

<md-tab-panels for="profile-tabs">
  <md-tab-panel style="padding: 16px;">
    <p style="margin: 0;">Your posts appear here.</p>
  </md-tab-panel>
  <md-tab-panel style="padding: 16px;">
    <p style="margin: 0;">Your replies appear here.</p>
  </md-tab-panel>
  <md-tab-panel style="padding: 16px;">
    <p style="margin: 0;">Posts you liked appear here.</p>
  </md-tab-panel>
</md-tab-panels>
```

To react to the switch (lazy-loading a panel, for example), listen on the tabs:

```js
document.getElementById('profile-tabs')
  .addEventListener('mdTabChange', (e) => console.log(e.detail.index, e.detail.previousIndex));
```

### 8.7 The full recipe library

Twenty-two more complete screens live in the documentation, each with a live
demo, the full markup, framework tabs, and production notes. When the user's
request matches one of these, read that page (append the slug to
`https://awc-ui.dev/recipes/`) instead of composing from scratch:

| Recipe slug | Screen |
|---|---|
| `two-factor-verification` | OTP entry, resend countdown, backup-codes dialog |
| `kpi-overview` | Stat tiles with sparklines + charts under a range switcher |
| `data-grid-console` | Bulk-action data table: filters, selection, undo |
| `server-fleet-status` | Table of hosts with meters, sparklines, status dots |
| `release-health-drilldown` | Table row → side-sheet master-detail with charts |
| `csv-import-wizard` | Stepper: upload, map columns, validate, import |
| `role-permission-assignment` | Transfer-list permissions with confirm dialog |
| `org-chart-explorer` | Searchable org chart with side-sheet profiles |
| `moderation-queue` | Verdict controls, confidence meter, card queue |
| `checkout-wizard` | Three-step commerce checkout with validation |
| `appointment-booking` | Date + time pickers inside a stepper flow |
| `survey-nps` | Paged survey using every input control |
| `notification-preferences` | Accordion × switch matrix, quiet hours |
| `app-shell` | Responsive rail/bar chrome, SSR-ready, zero CLS |
| `inbox-shell` | Three-zone list + reading-pane layout |
| `mobile-filter-sheet` | Bottom-sheet filters with applied-chip row |
| `product-reviews` | Rating input + per-star meter breakdown |
| `order-tracking` | Shipment timeline stepper with progress meter |
| `portfolio-markets` | Finance charts + holdings table + trade ticket |
| `pricing-page` | Plan cards, billing toggle, comparison table |
| `async-feedback-patterns` | Skeleton/progress/snackbar choreography rules |
| `charts-gallery` | Every chart component, live-retheming palette |

---

## §9 — Universal do's and don'ts

Apply to every component. Component-specific rules live in each manual.

### 9.1 API and styling

| ✅ Do | ❌ Don't |
|---|---|
| Use the custom element directly — it *is* the control, with its own `href` / `type` props | Wrap it in a native `<button>` / `<a>` (§7.3) |
| Set arrays and objects as **JS properties** (`el.items = [...]`) | Pass them as HTML attributes — they won't parse |
| Theme via `--md-<component>-*` properties, then `::part()` | Reach into shadow internals or override `.md-*` classes |
| Change appearance through design tokens (§4.1) | Hardcode hex colors, px spacing, shadows, or font stacks |
| Use `--md-sys-z-index-*` for your own overlays | Invent z-indexes that land under a menu |
| Use logical CSS (`margin-inline-start`, `inset-inline-end`) | Use `margin-left`, `right`, `padding-right` |
| Set `data-density` / `data-theme` / `dir` once, globally | Set them per component unless you mean a local exception |
| Listen to the component's `md*` events | Rely on native `click` — it fires even when the component's `disabled` / `loading` guard suppressed the action |
| Check the manual for the state prop name | Assume `checked`; `md-switch` uses `selected` |
| Render the element, then call its `@Method` | Call `.show()` on an element not yet in the DOM |

Toggling components flip their own state on activation and *then* emit. On
`md-button`, `mdClick` is cancelable — `preventDefault()` on it vetoes the
toggle and any navigation. `mdChange` fires after the flip and is not
cancelable. If a controlled parent rejects a change it must revert the child
explicitly.

`md-button` has a **toggle mode**: set `toggle` and the button flips its own
`selected` on each activation and exposes `aria-pressed`. `selected` is the
state, not the switch — set it for the initial pressed state and read it back
from `mdClick`'s `detail.selected`. Setting `toggle` and then styling
"pressed" yourself, or setting `selected` without `toggle` (which emits no
`aria-pressed` at all), both produce a control that lies to assistive tech.

### 9.2 Content and hierarchy

| ✅ Do | ❌ Don't |
|---|---|
| Use sentence case for all labels | Uppercase or title-case UI text |
| Keep one high-emphasis action per screen region | Compete `filled` buttons against each other |
| Use `soft-disabled` + `md-tooltip` for contextually-unavailable actions | Use `disabled` and remove it from tab order with no explanation |
| Localize every text prop and `aria-label` | Leave default English prop values in a translated app |

**`disabled` vs `soft-disabled`.** Both render the disabled appearance, but
`disabled` also removes the control from the tab order, so a keyboard or screen
reader user can never find out *why* it is off. `soft-disabled` keeps the
control focusable and announced while still blocking activation — which is what
lets an `md-tooltip` on it explain the gate. Use it whenever the reason is
informative rather than obvious.

Nesting rules — dialog inside a dialog, a component inside a native
`<button>` / `<a>`, tabs used as app navigation — live in §7.3.

### 9.3 Accessibility contract

The library ships WCAG 2.1 AA keyboard and ARIA wiring by default. These are the
rules you must not break:

1. **Every icon-only control gets an accessible name.** `md-icon-button`,
   `md-fab`, and icon-only `md-tab` are nameless without `aria-label` (or
   `aria-labelledby`). `md-fab` will also accept `label`, and warns in the
   console when it has neither.
2. **Every form field gets a `label` prop.** `placeholder` is not a label — it
   disappears on type.
3. **Don't break the tab order.** Every interactive control must be reachable by
   Tab and operable by Enter/Space. If you add `tabindex="-1"` to anything,
   have a reason.
4. **Don't write your own focus trap.** `md-dialog`, `md-bottom-sheet` and
   `md-side-sheet` trap focus while open and restore it to the trigger on
   close — including across shadow boundaries. Adding your own fights theirs.
5. **Don't wrap components in your own live regions.** `md-snackbar` announces
   itself (`politeness="polite"` by default, `"assertive"` when the message must
   interrupt). For an error that blocks the task, use `md-dialog`.
6. **Don't disable motion yourself.** Components honour
   `prefers-reduced-motion: reduce` internally.
7. **Directional icons do not auto-flip in RTL** — see §4.5.
8. **Re-verify contrast after overriding any colour role** — the library's AA
   testing covers the shipped palette only. The Theme Generator at
   <https://awc-ui.dev/theme-generator> runs the WCAG checks live (§4.2).

---

## §10 — Before you ship

1. **Every icon-only control has an accessible name.**
2. **Keyboard-only pass**: reach and operate every control; focus is always
   visible; no traps in dialogs/menus/sheets; focus returns to the trigger.
3. **Theme pass**: light *and* dark, if both are supported — and the attribute
   is set before first paint.
4. **RTL pass**, if an RTL locale ships — check directional icons specifically,
   and grep your own CSS for physical properties.
5. **Density pass** at the configured rung — no clipped labels, touch targets
   still adequate. Remember `density="0"` is inert; use
   `--md-sys-density-scale: 0` to opt a subtree out.
6. **Forms**: every control has a `name`; `required` blocks submit; `FormData`
   contains every field; reset works.
7. **No hardcoded strings** left in markup if the app is localized — including
   default prop values like `Search`, `Dismiss`, `No results`.
8. **No hardcoded design values** — grep the diff for hex colours, `px` radii,
   `box-shadow`, and `z-index` literals.
9. **Contrast** re-verified against AA if colour roles were overridden.
10. **SSR**: if server-rendered, confirm no hydration mismatch and that content
    is present with JS disabled.
11. **No shadow-internal CSS** — only tokens, custom properties, and `::part()`.
12. **Every `md-*` tag you emitted appears in §6.** If it doesn't, it doesn't
    exist.