fix(card): motion prop (state-domain pilot) + nested-interactive guard

- `motion` prop: the Card is the state-domain pilot. Becoming `selected` plays the
  preset once via `data-motion-state` (mount-guarded — animates on the transition,
  not on mount/deselect). `card-emerge` yields to the motion system when `motion`
  is set (otherwise toggling `data-motion-state` re-triggers the mount fade).
- Nested-interactive guard: clicking a control inside an interactive Card (a Footer
  button, a link) must not select the Card. `handleActivate`/`handleKeydown` bail
  when the event originates from an interactive descendant, and the `:active`
  press-scale is suppressed via `:not(:has(button:active, …))` — the press cascade
  reaches the ancestor `<button>`, which `stopPropagation` can't touch.
- Demo: `motion` chip control on the live Card.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/uix/eidos/components/card/card.css

@@ -68,8 +68,14 @@
 }
 
 /* Mount animation — fade-in + slide-up. Disabled by data-no-emerge
- * (long lists) and by prefers-reduced-motion. */
-[data-card]:not([data-no-emerge]) {
+ * (long lists) and by prefers-reduced-motion.
+ *
+ * `:not([data-animation-style])` — when the card opts into the motion system
+ * (the `motion` prop sets data-animation-style), THAT system owns the element's
+ * single `animation` property. card-emerge yields: otherwise toggling
+ * `data-motion-state` would flip animation-name card-emerge↔select-pop-in and
+ * re-trigger this mount fade on every deselect. */
+[data-card]:not([data-no-emerge]):not([data-animation-style]) {
 	animation: card-emerge var(--card-emerge-duration) var(--card-emerge-ease) both;
 }
 
@@ -197,7 +203,13 @@
 	background: var(--_card-track);
 }
 
-[data-card][data-interactive]:active:not([data-disabled]) {
+/* `:not(:has(…:active))` — when an INTERACTIVE descendant is being pressed (a
+ * Footer button, a link, a form control), the card is ALSO `:active` because the
+ * activation chain cascades to ancestors; without this guard pressing a control
+ * would press-scale the whole card. Pressing a control inside the card must not
+ * move the card. (Plain content presses still scale: only interactive descendants
+ * suppress it, so `:active` on the card's own surface is unaffected.) */
+[data-card][data-interactive]:active:not([data-disabled]):not(:has(button:active, a:active, input:active, select:active, textarea:active, [role='button']:active)) {
 	transform: scale(var(--card-press-scale));
 	transition-duration: var(--card-press-duration);
 }

src/uix/eidos/components/card/card.svelte

@@ -30,6 +30,7 @@
 		selected = false,
 		disabled = false,
 		noEmerge = false,
+		motion,
 		onSelect,
 		children,
 		...rest
@@ -40,6 +41,25 @@
 	const resolvedSize = $derived(eidos.resolve(size, 'md'));
 	const resolvedRounded = $derived(eidos.resolve(rounded, 'md'));
 
+	// State-domain motion (opt-in). `data-animation-style` selects the preset;
+	// `data-motion-state` drives its enter — kept SEPARATE from the semantic
+	// `data-state` so it never clobbers selected/idle.
+	const resolvedMotion = $derived(motion && motion !== 'none' ? motion : undefined);
+
+	// Play the preset only on a select TRANSITION (selected flips true post-mount),
+	// not on the initial mount and not on deselect (animate-on, snap-off). This also
+	// keeps it clear of the `card-emerge` mount animation.
+	let motionState = $state<'open' | undefined>(undefined);
+	let firstRun = true;
+	$effect(() => {
+		const isSelected = selected;
+		if (firstRun) {
+			firstRun = false;
+			return;
+		}
+		motionState = isSelected ? 'open' : undefined;
+	});
+
 	// Distinguish canonical ColorRole from arbitrary CSS color string.
 	// COLOR_ROLES = ['primary', 'secondary', 'neutral', 'affirm', ...]
 	const isCanonicalColor = $derived(
@@ -50,13 +70,29 @@
 
 	const tag = $derived(interactive ? 'button' : 'div');
 
+	// A click/keypress that originates from an interactive descendant (a Footer
+	// action, a link, a form control) must NOT activate the card — running that
+	// control should not select the card. The companion CSS (`:not(:has(…:active))`)
+	// suppresses the press-scale for the same case; together, pressing a control
+	// inside the card leaves the card untouched.
+	function isFromNestedInteractive(event: Event): boolean {
+		const target = event.target as Element | null;
+		if (!target || target === event.currentTarget) return false;
+		const el = target.closest(
+			'button, a[href], input, select, textarea, label, [role="button"], [role="link"]'
+		);
+		return !!el && el !== event.currentTarget;
+	}
+
 	function handleActivate(event: MouseEvent | KeyboardEvent) {
 		if (!interactive || disabled) return;
+		if (isFromNestedInteractive(event)) return;
 		onSelect?.(event);
 	}
 
 	function handleKeydown(event: KeyboardEvent) {
 		if (!interactive || disabled) return;
+		if (isFromNestedInteractive(event)) return;
 		// `<button>` activates on Enter/Space natively, but when the
 		// consumer overrides the tag via composition we still want
 		// keyboard parity.
@@ -80,6 +116,8 @@
 	data-selected={selected ? '' : undefined}
 	data-disabled={disabled ? '' : undefined}
 	data-state={selected ? 'selected' : 'idle'}
+	data-animation-style={resolvedMotion}
+	data-motion-state={resolvedMotion ? motionState : undefined}
 	data-no-emerge={noEmerge ? '' : undefined}
 	type={interactive ? 'button' : undefined}
 	disabled={interactive && disabled ? true : undefined}

src/uix/eidos/components/card/types.ts

@@ -7,6 +7,7 @@ import type {
 	ShapeFamily,
 	Size
 } from '$uix/eidos/lib/types';
+import type { MotionPresetName } from '$uix/eidos/lib/motion/registry';
 import type { BoxProps } from '../box/types';
 
 /**
@@ -95,6 +96,21 @@ export type CardProps = Omit<BoxProps, 'display'> & {
 	 * @default false
 	 */
 	selected?: boolean;
+	/**
+	 * State-domain motion preset for the `selected` transition. When set
+	 * (and not `'none'`), the card plays the preset once each time it
+	 * BECOMES selected — driven by the dedicated `data-motion-state` so it
+	 * never clobbers the card's semantic `data-state`. Animate-on /
+	 * snap-off: deselecting and the initial mount don't animate (composes
+	 * with — does not replace — the recipe's `box-shadow` ring transition).
+	 * Use an EMPHASIS preset (`'select-pop'`); a presence preset
+	 * (`'scale-fade'`…) would flash the still-visible card from invisible.
+	 * Setting `motion` makes the motion system own the card's single
+	 * `animation`, so it suppresses the default mount `card-emerge` fade
+	 * (the entrance yields to the state emphasis).
+	 * @default undefined
+	 */
+	motion?: MotionPresetName;
 	/**
 	 * Disable interaction (only meaningful when `interactive`). Adds
 	 * `data-disabled` + `aria-disabled` and suppresses the

web/routes/uix/components/card/+page.svelte

@@ -7,6 +7,7 @@
 		type CardRounded
 	} from '$uix/eidos/components/card';
 	import { SHAPE_FAMILIES, type ShapeFamily } from '$uix/eidos/lib/types';
+	import type { MotionPresetName } from '$uix/eidos/lib/motion/registry';
 	import { Box } from '$uix/eidos/components/box';
 	import { Stack } from '$uix/eidos/components/stack';
 	import { Avatar } from '$uix/eidos/components/avatar';
@@ -28,10 +29,11 @@
 	let color = $state<CardColor>('neutral');
 	let rounded = $state<CardRounded>('md');
 	let shape = $state<ShapeFamily>('rounded');
-	let interactive = $state(false);
+	let interactive = $state(true);
 	let selected = $state(false);
 	let disabled = $state(false);
 	let noEmerge = $state(false);
+	let motion = $state<MotionPresetName>('select-pop');
 	let titleText = $state('Welcome aboard');
 	let descriptionText = $state(
 		'Your workspace is ready. Pick where you want to start.'
@@ -56,6 +58,8 @@
 		'loss'
 	];
 	const roundeds: CardRounded[] = ['sm', 'md', 'lg'];
+	// State-domain motion: `select-pop` is the emphasis preset; `none` opts out.
+	const motions: MotionPresetName[] = ['none', 'select-pop'];
 
 	// ── Compiled morfo ────────────────────────────────────────────────────
 	const compiled = compileMorfo(cardMorfo);
@@ -118,6 +122,7 @@
 			selected && '  selected',
 			disabled && '  disabled',
 			noEmerge && '  noEmerge',
+			motion !== 'none' && `  motion="${motion}"`,
 			interactive && '  onSelect={() => pick(id)}',
 			'>',
 			'  <Card.Header>',
@@ -188,6 +193,7 @@
 					{selected}
 					{disabled}
 					{noEmerge}
+					{motion}
 					onSelect={handleSelect}
 					style="max-inline-size: 28rem; inline-size: 100%;"
 				>
@@ -341,6 +347,14 @@
 						<span data-uix-switch-label>{noEmerge ? 'on' : 'off'}</span>
 					</span>
 				</label>
+				<label data-uix-control>
+					<span data-uix-control-label>motion <span data-uix-control-hint>plays when the card becomes selected — click the card surface, not its buttons (state domain)</span></span>
+					<span data-uix-chips role="radiogroup">
+						{#each motions as m (m)}
+							<button data-uix-chip data-active={motion === m} onclick={() => (motion = m)}>{m}</button>
+						{/each}
+					</span>
+				</label>
 				<label data-uix-control>
 					<span data-uix-control-label>title</span>
 					<input