date-range-picker: YearRangeView + MonthRangeView (kind grids)

Completes the kind contract for the range picker. The popover used to
render the day-grid range calendar regardless of kind; now it switches
to a year-grid or month-grid view that handles range selection on the
appropriate granularity.

New Eidos parts:
- <DateRangePicker.YearView>: 3×4 decade grid with prev/next decade
  buttons. Selection state machine (mirrors the day-grid range
  selection):
  * empty → click sets startValue (and clears endValue)
  * pending (start set, no end) → click sets endValue. Swap if the
    clicked year is before the existing start.
  * complete (both set) → click resets to a fresh start + clears end.
  Year endpoints normalise to Jan 1 (start) / Dec 31 (end).
- <DateRangePicker.MonthView>: 3×4 month grid for the placeholder's
  year, with prev/next year navigation. Same state machine using
  `year*12 + month` as the comparison key, so ranges span multi-year
  boundaries cleanly. Start = day 1; end = last day of the month
  (computed via Date(y, m, 0).getDate()).
- Localised month names via DateFormatter(locale, { month: 'short' }).

Index + CSS:
- index.ts: registers YearView + MonthView on the DateRangePicker
  namespace.
- date-range-picker.css: shared grid layout (3 columns, gap-2),
  hover surface-overlay, selected cells get primary-solid +
  content-on-solid, in-range cells get color-mix(primary-solid 22%,
  transparent) as a stripe with border-radius:0 (start/end keep
  their outer corner radius). Reduced-motion respected.

Demo:
- {#if kind === 'year'} → <YearView>; {:else if 'month'} → <MonthView>;
  {:else} → existing day calendar.
- pickerFooter snippet rendered once at the Content level (removed
  the inline render at the end of calendarBody to avoid duplication).

Verified in browser:
1. kind='year' chip → popover shows year grid '2020 – 2031'.
2. Click 2024 → cell marked start (purple solid).
3. Click 2027 → cell marked end, 2025-2026 marked in-range. trace
   shows 'range 2024-01-01 -> 2027-12-31'. Popover stays open
   (closeOnRangeSelect=false in the demo).

0 type errors, 67/67 component:audit PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/uix/eidos/components/date-range-picker/date-range-picker-month-view.svelte

@@ -0,0 +1,124 @@
+<script lang="ts">
+	import { DateRangePickerProvider } from '$soma/components/date-range-picker';
+	import { CalendarDate, DateFormatter } from '$libs/days';
+	import type { HTMLAttributes } from 'svelte/elements';
+
+	// Month-grid range view (kind='month'). 3×4 month grid for the
+	// placeholder's year + year nav. Same selection state machine as
+	// the year view; comparisons use a `year*12 + month` key so ranges
+	// can span multiple years.
+	interface MonthRangeViewProps extends HTMLAttributes<HTMLDivElement> {}
+
+	const { ...rest }: MonthRangeViewProps = $props();
+
+	const provider = DateRangePickerProvider.require();
+
+	const startVal = $derived(provider.opts.startValue.current);
+	const endVal = $derived(provider.opts.endValue.current);
+	const placeholder = $derived(provider.opts.placeholder.current);
+	const year = $derived(placeholder.year);
+
+	const months = $derived(Array.from({ length: 12 }, (_, i) => i + 1));
+
+	const formatter = $derived.by(() => {
+		const locale = provider.opts.locale.current || 'en-US';
+		return new DateFormatter(locale, { month: 'short' });
+	});
+
+	function monthLabel(month: number): string {
+		return formatter.format(new Date(year, month - 1, 1));
+	}
+
+	const startKey = $derived(startVal ? startVal.year * 12 + (startVal.month - 1) : undefined);
+	const endKey = $derived(endVal ? endVal.year * 12 + (endVal.month - 1) : undefined);
+
+	function keyFor(month: number): number {
+		return year * 12 + (month - 1);
+	}
+
+	function selectMonth(month: number) {
+		const s = startVal;
+		const e = endVal;
+		const isComplete = s !== undefined && e !== undefined;
+
+		if (!s || isComplete) {
+			const next = new CalendarDate(year, month, 1);
+			provider.opts.startValue.current = next;
+			provider.opts.endValue.current = undefined;
+			provider.opts.placeholder.current = next;
+			return;
+		}
+
+		// Pending end. Swap if the picked month is before start.
+		const sKey = s.year * 12 + (s.month - 1);
+		const k = keyFor(month);
+		const newDate = new CalendarDate(year, month, 1);
+		if (k < sKey) {
+			// Mark end as the last day of the original start month.
+			const endOfStartMonth = new CalendarDate(s.year, s.month, daysInMonth(s.year, s.month));
+			provider.opts.endValue.current = endOfStartMonth;
+			provider.opts.startValue.current = newDate;
+		} else {
+			const endOfMonth = new CalendarDate(year, month, daysInMonth(year, month));
+			provider.opts.endValue.current = endOfMonth;
+		}
+		provider.handleRangeSelect();
+	}
+
+	function stepYear(direction: -1 | 1) {
+		const p = placeholder;
+		provider.opts.placeholder.current = new CalendarDate(p.year + direction, p.month, p.day);
+	}
+
+	function classFor(month: number): { start: boolean; end: boolean; inRange: boolean } {
+		if (startKey === undefined) return { start: false, end: false, inRange: false };
+		const k = keyFor(month);
+		const start = k === startKey;
+		const end = endKey !== undefined && k === endKey;
+		const inRange =
+			endKey !== undefined && k > Math.min(startKey, endKey) && k < Math.max(startKey, endKey);
+		return { start, end, inRange };
+	}
+
+	function daysInMonth(year: number, month: number): number {
+		return new Date(year, month, 0).getDate();
+	}
+</script>
+
+<div data-date-range-picker-month-view role="grid" aria-label="Select month range" {...rest}>
+	<div data-date-range-picker-month-view-header>
+		<button
+			type="button"
+			data-date-range-picker-month-view-prev
+			aria-label="Previous year"
+			onclick={() => stepYear(-1)}
+		>
+			‹
+		</button>
+		<span data-date-range-picker-month-view-heading>{year}</span>
+		<button
+			type="button"
+			data-date-range-picker-month-view-next
+			aria-label="Next year"
+			onclick={() => stepYear(1)}
+		>
+			›
+		</button>
+	</div>
+	<div data-date-range-picker-month-view-grid>
+		{#each months as month (month)}
+			{@const c = classFor(month)}
+			<button
+				type="button"
+				data-date-range-picker-month-view-cell
+				data-range-start={c.start ? '' : undefined}
+				data-range-end={c.end ? '' : undefined}
+				data-in-range={c.inRange ? '' : undefined}
+				aria-pressed={c.start || c.end}
+				onclick={() => selectMonth(month)}
+			>
+				{monthLabel(month)}
+			</button>
+		{/each}
+	</div>
+</div>

src/uix/eidos/components/date-range-picker/date-range-picker-year-view.svelte

@@ -0,0 +1,110 @@
+<script lang="ts">
+	import { DateRangePickerProvider } from '$soma/components/date-range-picker';
+	import { CalendarDate } from '$libs/days';
+	import type { HTMLAttributes } from 'svelte/elements';
+
+	// Year-grid range view (kind='year'). 3×4 decade grid + decade nav.
+	//
+	// Selection state machine (mirrors the day-grid range selection):
+	// - Empty (neither start nor end set): click sets startValue (and
+	//   clears endValue).
+	// - Pending (start set, no end): click sets endValue. If the clicked
+	//   year is before startValue, swap them so start <= end.
+	// - Complete (both set): click resets to a fresh start + clears end.
+	//
+	// Year endpoints normalise to Jan 1 for start, Dec 31 for end.
+	interface YearRangeViewProps extends HTMLAttributes<HTMLDivElement> {}
+
+	const { ...rest }: YearRangeViewProps = $props();
+
+	const provider = DateRangePickerProvider.require();
+
+	const startVal = $derived(provider.opts.startValue.current);
+	const endVal = $derived(provider.opts.endValue.current);
+	const placeholder = $derived(provider.opts.placeholder.current);
+
+	// Decade window: anchor on startValue or placeholder, snap to decade.
+	const anchorYear = $derived(startVal?.year ?? placeholder.year);
+	const decadeStart = $derived(anchorYear - (anchorYear % 10));
+	const years = $derived(Array.from({ length: 12 }, (_, i) => decadeStart + i));
+
+	function selectYear(year: number) {
+		const s = startVal;
+		const e = endVal;
+		const isComplete = s !== undefined && e !== undefined;
+
+		if (!s || isComplete) {
+			// Fresh start.
+			provider.opts.startValue.current = new CalendarDate(year, 1, 1);
+			provider.opts.endValue.current = undefined;
+			provider.opts.placeholder.current = new CalendarDate(year, 1, 1);
+			return;
+		}
+
+		// Pending end: set the second endpoint, swap if reversed.
+		const startYear = s.year;
+		if (year < startYear) {
+			provider.opts.endValue.current = new CalendarDate(startYear, 12, 31);
+			provider.opts.startValue.current = new CalendarDate(year, 1, 1);
+		} else {
+			provider.opts.endValue.current = new CalendarDate(year, 12, 31);
+		}
+		provider.handleRangeSelect();
+	}
+
+	function stepDecade(direction: -1 | 1) {
+		const p = placeholder;
+		provider.opts.placeholder.current = new CalendarDate(p.year + direction * 10, p.month, p.day);
+	}
+
+	function classFor(year: number): { start: boolean; end: boolean; inRange: boolean } {
+		const sy = startVal?.year;
+		const ey = endVal?.year;
+		if (sy === undefined) return { start: false, end: false, inRange: false };
+		const start = year === sy;
+		const end = ey !== undefined && year === ey;
+		const inRange =
+			ey !== undefined && year > Math.min(sy, ey) && year < Math.max(sy, ey);
+		return { start, end, inRange };
+	}
+</script>
+
+<div data-date-range-picker-year-view role="grid" aria-label="Select year range" {...rest}>
+	<div data-date-range-picker-year-view-header>
+		<button
+			type="button"
+			data-date-range-picker-year-view-prev
+			aria-label="Previous decade"
+			onclick={() => stepDecade(-1)}
+		>
+			‹
+		</button>
+		<span data-date-range-picker-year-view-heading>
+			{decadeStart} – {decadeStart + 11}
+		</span>
+		<button
+			type="button"
+			data-date-range-picker-year-view-next
+			aria-label="Next decade"
+			onclick={() => stepDecade(1)}
+		>
+			›
+		</button>
+	</div>
+	<div data-date-range-picker-year-view-grid>
+		{#each years as year (year)}
+			{@const c = classFor(year)}
+			<button
+				type="button"
+				data-date-range-picker-year-view-cell
+				data-range-start={c.start ? '' : undefined}
+				data-range-end={c.end ? '' : undefined}
+				data-in-range={c.inRange ? '' : undefined}
+				aria-pressed={c.start || c.end}
+				onclick={() => selectYear(year)}
+			>
+				{year}
+			</button>
+		{/each}
+	</div>
+</div>

src/uix/eidos/components/date-range-picker/date-range-picker.css

@@ -824,6 +824,115 @@
 	}
 }
 
+/* ── Range Year-view + Month-view (kind='year' / 'month') ────────────────── */
+
+[data-date-range-picker-year-view],
+[data-date-range-picker-month-view] {
+	display: flex;
+	flex-direction: column;
+	gap: var(--space-3);
+	inline-size: min(20rem, 100%);
+}
+
+[data-date-range-picker-year-view-header],
+[data-date-range-picker-month-view-header] {
+	display: flex;
+	align-items: center;
+	justify-content: space-between;
+	gap: var(--space-2);
+}
+
+[data-date-range-picker-year-view-heading],
+[data-date-range-picker-month-view-heading] {
+	font-weight: var(--font-weight-semibold);
+	color: var(--color-content-primary);
+}
+
+[data-date-range-picker-year-view-prev],
+[data-date-range-picker-year-view-next],
+[data-date-range-picker-month-view-prev],
+[data-date-range-picker-month-view-next] {
+	min-block-size: var(--control-height-sm);
+	min-inline-size: var(--control-height-sm);
+	border-radius: var(--radius-md);
+	border: var(--border-width) solid transparent;
+	background: transparent;
+	color: var(--color-content-primary);
+	cursor: pointer;
+	font: inherit;
+	font-size: var(--font-size-md);
+}
+
+[data-date-range-picker-year-view-prev]:hover,
+[data-date-range-picker-year-view-next]:hover,
+[data-date-range-picker-month-view-prev]:hover,
+[data-date-range-picker-month-view-next]:hover {
+	background: var(--color-surface-overlay);
+}
+
+[data-date-range-picker-year-view-grid],
+[data-date-range-picker-month-view-grid] {
+	display: grid;
+	grid-template-columns: repeat(3, minmax(0, 1fr));
+	gap: var(--space-2);
+}
+
+[data-date-range-picker-year-view-cell],
+[data-date-range-picker-month-view-cell] {
+	min-block-size: var(--control-height-md);
+	border-radius: var(--radius-md);
+	border: var(--border-width) solid transparent;
+	background: transparent;
+	color: var(--color-content-primary);
+	cursor: pointer;
+	font: inherit;
+	font-size: var(--font-size-sm);
+	transition:
+		background var(--duration-fast) var(--ease-default),
+		color var(--duration-fast) var(--ease-default);
+}
+
+[data-date-range-picker-year-view-cell]:hover,
+[data-date-range-picker-month-view-cell]:hover {
+	background: var(--color-surface-overlay);
+}
+
+/* Range stripe: in-range cells get a tinted background. Start and end
+ * cells overlay it with the solid primary fill. */
+[data-date-range-picker-year-view-cell][data-in-range],
+[data-date-range-picker-month-view-cell][data-in-range] {
+	background: color-mix(in srgb, var(--color-primary-solid) 22%, transparent);
+	border-radius: 0;
+}
+
+[data-date-range-picker-year-view-cell][data-range-start],
+[data-date-range-picker-year-view-cell][data-range-end],
+[data-date-range-picker-month-view-cell][data-range-start],
+[data-date-range-picker-month-view-cell][data-range-end] {
+	background: var(--color-primary-solid);
+	color: var(--color-content-on-solid);
+	border-color: var(--color-primary-border);
+}
+
+/* Round the open edge of the range strip on start / end cells. */
+[data-date-range-picker-year-view-cell][data-range-start],
+[data-date-range-picker-month-view-cell][data-range-start] {
+	border-start-start-radius: var(--radius-md);
+	border-end-start-radius: var(--radius-md);
+}
+
+[data-date-range-picker-year-view-cell][data-range-end],
+[data-date-range-picker-month-view-cell][data-range-end] {
+	border-start-end-radius: var(--radius-md);
+	border-end-end-radius: var(--radius-md);
+}
+
+[data-date-range-picker-year-view-cell]:focus-visible,
+[data-date-range-picker-month-view-cell]:focus-visible {
+	outline: var(--focus-ring-width) solid var(--color-primary-border);
+	outline-offset: var(--focus-ring-offset);
+}
+
 /* ── Footer (Clear / Cancel / Close action row) ──────────────────────────── */
 
 [data-date-range-picker-footer] {

src/uix/eidos/components/date-range-picker/index.ts

@@ -10,6 +10,8 @@ import Overlay from '../popover/popover-overlay.svelte';
 import Arrow from '../popover/popover-arrow.svelte';
 import Close from './date-range-picker-close.svelte';
 import Footer from './date-range-picker-footer.svelte';
+import YearView from './date-range-picker-year-view.svelte';
+import MonthView from './date-range-picker-month-view.svelte';
 import Clear from './date-range-picker-clear.svelte';
 import Cancel from './date-range-picker-cancel.svelte';
 import Header from './date-range-picker-header.svelte';
@@ -36,6 +38,8 @@ type DateRangePickerNamespace = typeof DateRangePickerComponent & {
 	Arrow: typeof Arrow;
 	Close: typeof Close;
 	Footer: typeof Footer;
+	YearView: typeof YearView;
+	MonthView: typeof MonthView;
 	Clear: typeof Clear;
 	Cancel: typeof Cancel;
 	Label: typeof Label;
@@ -66,6 +70,8 @@ DateRangePicker.Content = Content;
 DateRangePicker.Arrow = Arrow;
 DateRangePicker.Close = Close;
 DateRangePicker.Footer = Footer;
+DateRangePicker.YearView = YearView;
+DateRangePicker.MonthView = MonthView;
 DateRangePicker.Clear = Clear;
 DateRangePicker.Cancel = Cancel;
 DateRangePicker.Label = Label;

web/routes/uix/components/date-range-picker/+page.svelte

@@ -539,11 +539,18 @@
 					</div>
 					<DateRangePicker.Portal>
 						<DateRangePicker.Content align="end" sideOffset={10} collisionPadding={12}>
+							{#if kind === 'year'}
+								<DateRangePicker.YearView />
+							{:else if kind === 'month'}
+								<DateRangePicker.MonthView />
+							{:else}
 								<DateRangePicker.Calendar>
 									{#snippet children(args: DateRangePickerCalendarSnippetProps)}
 										{@render calendarBody(args)}
 									{/snippet}
 								</DateRangePicker.Calendar>
+							{/if}
+							{@render pickerFooter()}
 						</DateRangePicker.Content>
 					</DateRangePicker.Portal>
 				</DateRangePicker>
@@ -1082,7 +1089,6 @@
 			</div>
 		{/each}
 	</div>
-	{@render pickerFooter()}
 {/snippet}
 
 {#snippet pickerFooter()}