feat: replace all native date inputs with custom DatePicker component

Add theme-aware DatePicker with pill display, calendar dropdown, prev/next
day arrows, bilingual month/weekday names, and min/max support. Replace all
15 native <input type="date"> elements across fitness, tasks, and cospend.

src/lib/components/DatePicker.svelte

@@ -0,0 +1,354 @@
+<script>
+	import { ChevronLeft, ChevronRight, Calendar } from '@lucide/svelte';
+
+	let { value = $bindable(''), lang = 'en', min = '', max = '' } = $props();
+
+	let open = $state(false);
+	let pickerRef = $state(null);
+
+	const WEEKDAYS_EN = ['Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa', 'Su'];
+	const WEEKDAYS_DE = ['Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa', 'So'];
+	const MONTHS_EN = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];
+	const MONTHS_DE = ['Januar', 'Februar', 'März', 'April', 'Mai', 'Juni', 'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'];
+
+	const weekdays = $derived(lang === 'de' ? WEEKDAYS_DE : WEEKDAYS_EN);
+	const months = $derived(lang === 'de' ? MONTHS_DE : MONTHS_EN);
+
+	// The month being viewed in the calendar (independent of selected value)
+	let viewYear = $state(0);
+	let viewMonth = $state(0);
+
+	$effect(() => {
+		if (value) {
+			const d = new Date(value + 'T12:00:00');
+			viewYear = d.getFullYear();
+			viewMonth = d.getMonth();
+		} else {
+			const now = new Date();
+			viewYear = now.getFullYear();
+			viewMonth = now.getMonth();
+		}
+	});
+
+	const todayStr = new Date().toISOString().slice(0, 10);
+
+	const displayDate = $derived.by(() => {
+		if (!value) return lang === 'en' ? 'Select date' : 'Datum wählen';
+		if (value === todayStr) return lang === 'en' ? 'Today' : 'Heute';
+		const d = new Date(value + 'T12:00:00');
+		return d.toLocaleDateString(lang === 'de' ? 'de-DE' : 'en-US', { weekday: 'short', month: 'short', day: 'numeric' });
+	});
+
+	function isDisabled(dateStr) {
+		if (min && dateStr < min) return true;
+		if (max && dateStr > max) return true;
+		return false;
+	}
+
+	function navigateDate(delta) {
+		const d = new Date((value || todayStr) + 'T12:00:00');
+		d.setDate(d.getDate() + delta);
+		const next = d.toISOString().slice(0, 10);
+		if (!isDisabled(next)) value = next;
+	}
+
+	function navMonth(delta) {
+		viewMonth += delta;
+		if (viewMonth > 11) { viewMonth = 0; viewYear++; }
+		if (viewMonth < 0) { viewMonth = 11; viewYear--; }
+	}
+
+	function selectDay(dateStr) {
+		value = dateStr;
+		open = false;
+	}
+
+	function goToday() {
+		value = todayStr;
+		open = false;
+	}
+
+	const calendarDays = $derived.by(() => {
+		const first = new Date(viewYear, viewMonth, 1);
+		// Monday=0 based offset
+		let startDay = first.getDay() - 1;
+		if (startDay < 0) startDay = 6;
+
+		const daysInMonth = new Date(viewYear, viewMonth + 1, 0).getDate();
+		const daysInPrevMonth = new Date(viewYear, viewMonth, 0).getDate();
+
+		/** @type {{ date: string, day: number, currentMonth: boolean, isToday: boolean, isSelected: boolean }[]} */
+		const days = [];
+
+		// Previous month trailing days
+		for (let i = startDay - 1; i >= 0; i--) {
+			const d = daysInPrevMonth - i;
+			const m = viewMonth === 0 ? 11 : viewMonth - 1;
+			const y = viewMonth === 0 ? viewYear - 1 : viewYear;
+			const dateStr = `${y}-${String(m + 1).padStart(2, '0')}-${String(d).padStart(2, '0')}`;
+			days.push({ date: dateStr, day: d, currentMonth: false, isToday: dateStr === todayStr, isSelected: dateStr === value, disabled: isDisabled(dateStr) });
+		}
+
+		// Current month
+		for (let d = 1; d <= daysInMonth; d++) {
+			const dateStr = `${viewYear}-${String(viewMonth + 1).padStart(2, '0')}-${String(d).padStart(2, '0')}`;
+			days.push({ date: dateStr, day: d, currentMonth: true, isToday: dateStr === todayStr, isSelected: dateStr === value, disabled: isDisabled(dateStr) });
+		}
+
+		// Next month leading days (fill to complete rows of 7)
+		const remaining = 7 - (days.length % 7);
+		if (remaining < 7) {
+			for (let d = 1; d <= remaining; d++) {
+				const m = viewMonth === 11 ? 0 : viewMonth + 1;
+				const y = viewMonth === 11 ? viewYear + 1 : viewYear;
+				const dateStr = `${y}-${String(m + 1).padStart(2, '0')}-${String(d).padStart(2, '0')}`;
+				days.push({ date: dateStr, day: d, currentMonth: false, isToday: dateStr === todayStr, isSelected: dateStr === value, disabled: isDisabled(dateStr) });
+			}
+		}
+
+		return days;
+	});
+
+	// Close on outside click
+	function handleClickOutside(e) {
+		if (pickerRef && !pickerRef.contains(e.target)) {
+			open = false;
+		}
+	}
+
+	$effect(() => {
+		if (open) {
+			document.addEventListener('pointerdown', handleClickOutside);
+			return () => document.removeEventListener('pointerdown', handleClickOutside);
+		}
+	});
+</script>
+
+<div class="datepicker" bind:this={pickerRef}>
+	<div class="dp-pill">
+		<button type="button" class="dp-arrow" onclick={() => navigateDate(-1)} aria-label="Previous day">
+			<ChevronLeft size={16} />
+		</button>
+		<button type="button" class="dp-display" onclick={() => open = !open}>
+			<Calendar size={14} />
+			{displayDate}
+		</button>
+		<button type="button" class="dp-arrow" onclick={() => navigateDate(1)} aria-label="Next day">
+			<ChevronRight size={16} />
+		</button>
+	</div>
+
+	{#if open}
+		<div class="dp-dropdown">
+			<div class="dp-header">
+				<button type="button" class="dp-nav" onclick={() => navMonth(-1)} aria-label="Previous month">
+					<ChevronLeft size={16} />
+				</button>
+				<span class="dp-month-label">{months[viewMonth]} {viewYear}</span>
+				<button type="button" class="dp-nav" onclick={() => navMonth(1)} aria-label="Next month">
+					<ChevronRight size={16} />
+				</button>
+			</div>
+
+			<div class="dp-weekdays">
+				{#each weekdays as wd (wd)}
+					<span class="dp-wd">{wd}</span>
+				{/each}
+			</div>
+
+			<div class="dp-grid">
+				{#each calendarDays as day (day.date)}
+					<button
+						type="button"
+						class="dp-day"
+						class:other-month={!day.currentMonth}
+						class:today={day.isToday}
+						class:selected={day.isSelected}
+						class:disabled={day.disabled}
+						disabled={day.disabled}
+						onclick={() => selectDay(day.date)}
+					>
+						{day.day}
+					</button>
+				{/each}
+			</div>
+
+			{#if value !== todayStr}
+				<button type="button" class="dp-today-btn" onclick={goToday}>
+					{lang === 'en' ? 'Today' : 'Heute'}
+				</button>
+			{/if}
+		</div>
+	{/if}
+</div>
+
+<style>
+	.datepicker {
+		position: relative;
+		display: inline-flex;
+	}
+
+	/* Pill row */
+	.dp-pill {
+		display: flex;
+		align-items: center;
+		background: var(--color-bg-tertiary);
+		border: 1px solid var(--color-border);
+		border-radius: var(--radius-pill);
+		overflow: hidden;
+	}
+	.dp-arrow {
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		padding: 0.35rem 0.4rem;
+		background: none;
+		border: none;
+		color: var(--color-text-secondary);
+		cursor: pointer;
+		transition: color var(--transition-normal), background var(--transition-normal);
+	}
+	.dp-arrow:hover {
+		color: var(--color-text-primary);
+		background: var(--color-bg-elevated);
+	}
+	.dp-display {
+		display: flex;
+		align-items: center;
+		gap: 0.35rem;
+		padding: 0.35rem 0.5rem;
+		background: none;
+		border: none;
+		border-left: 1px solid var(--color-border);
+		border-right: 1px solid var(--color-border);
+		color: var(--color-text-secondary);
+		font-size: 0.8rem;
+		font-weight: 500;
+		cursor: pointer;
+		white-space: nowrap;
+		transition: color var(--transition-normal), background var(--transition-normal);
+	}
+	.dp-display:hover {
+		color: var(--color-text-primary);
+		background: var(--color-bg-elevated);
+	}
+
+	/* Dropdown calendar */
+	.dp-dropdown {
+		position: absolute;
+		top: calc(100% + 0.4rem);
+		left: 50%;
+		transform: translateX(-50%);
+		background: var(--color-surface);
+		border: 1px solid var(--color-border);
+		border-radius: var(--radius-lg);
+		box-shadow: var(--shadow-lg);
+		padding: 0.6rem;
+		z-index: 200;
+		min-width: 260px;
+	}
+
+	.dp-header {
+		display: flex;
+		align-items: center;
+		justify-content: space-between;
+		margin-bottom: 0.4rem;
+	}
+	.dp-month-label {
+		font-size: 0.8rem;
+		font-weight: 700;
+		color: var(--color-text-primary);
+	}
+	.dp-nav {
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		padding: 0.25rem;
+		background: none;
+		border: none;
+		border-radius: var(--radius-sm);
+		color: var(--color-text-secondary);
+		cursor: pointer;
+		transition: background var(--transition-normal), color var(--transition-normal);
+	}
+	.dp-nav:hover {
+		background: var(--color-bg-elevated);
+		color: var(--color-text-primary);
+	}
+
+	.dp-weekdays {
+		display: grid;
+		grid-template-columns: repeat(7, 1fr);
+		margin-bottom: 0.2rem;
+	}
+	.dp-wd {
+		text-align: center;
+		font-size: 0.6rem;
+		font-weight: 600;
+		text-transform: uppercase;
+		letter-spacing: 0.04em;
+		color: var(--color-text-tertiary);
+		padding: 0.2rem 0;
+	}
+
+	.dp-grid {
+		display: grid;
+		grid-template-columns: repeat(7, 1fr);
+		gap: 2px;
+	}
+	.dp-day {
+		display: flex;
+		align-items: center;
+		justify-content: center;
+		width: 100%;
+		aspect-ratio: 1;
+		border: none;
+		border-radius: var(--radius-sm);
+		background: none;
+		color: var(--color-text-primary);
+		font-size: 0.78rem;
+		font-weight: 500;
+		cursor: pointer;
+		transition: background var(--transition-normal), color var(--transition-normal);
+	}
+	.dp-day:hover {
+		background: var(--color-bg-elevated);
+	}
+	.dp-day.other-month {
+		color: var(--color-text-tertiary);
+	}
+	.dp-day.disabled {
+		opacity: 0.3;
+		cursor: not-allowed;
+	}
+	.dp-day.today {
+		font-weight: 700;
+		box-shadow: inset 0 0 0 1.5px var(--color-primary);
+	}
+	.dp-day.selected {
+		background: var(--color-primary);
+		color: var(--color-text-on-primary);
+		font-weight: 700;
+	}
+	.dp-day.selected:hover {
+		background: var(--color-primary-hover);
+	}
+
+	.dp-today-btn {
+		display: block;
+		width: 100%;
+		margin-top: 0.4rem;
+		padding: 0.3rem;
+		background: none;
+		border: 1px solid var(--color-border);
+		border-radius: var(--radius-sm);
+		color: var(--color-primary);
+		font-size: 0.75rem;
+		font-weight: 600;
+		cursor: pointer;
+		transition: background var(--transition-normal);
+	}
+	.dp-today-btn:hover {
+		background: var(--color-bg-elevated);
+	}
+</style>

src/lib/components/fitness/PeriodTracker.svelte

@@ -1,6 +1,7 @@
 <script>
 	import { t } from '$lib/js/fitnessI18n';
 	import { Trash2, Plus, Pencil, UserPlus, X, ChevronLeft, ChevronRight } from '@lucide/svelte';
+	import DatePicker from '$lib/components/DatePicker.svelte';
 	import { toast } from '$lib/js/toast.svelte';
 	import { confirm } from '$lib/js/confirmDialog.svelte';
 	import ProfilePicture from '$lib/components/cospend/ProfilePicture.svelte';
@@ -748,11 +749,11 @@
 							<div class="add-row">
 								<label>
 									{t('period_start', lang)}
-									<input type="date" bind:value={addStart} max={todayStr} />
+									<DatePicker bind:value={addStart} max={todayStr} {lang} />
 								</label>
 								<label>
 									{t('period_end', lang)}
-									<input type="date" bind:value={addEnd} min={addStart} max={todayStr} />
+									<DatePicker bind:value={addEnd} min={addStart} max={todayStr} {lang} />
 								</label>
 							</div>
 							<div class="add-actions">
@@ -773,11 +774,11 @@
 								<div class="add-row">
 									<label>
 										{t('period_start', lang)}
-										<input type="date" bind:value={editStart} />
+										<DatePicker bind:value={editStart} {lang} />
 									</label>
 									<label>
 										{t('period_end', lang)}
-										<input type="date" bind:value={editEnd} min={editStart} />
+										<DatePicker bind:value={editEnd} min={editStart} {lang} />
 									</label>
 								</div>
 								<div class="add-actions">
@@ -836,11 +837,11 @@
 						<div class="add-row">
 							<label>
 								{t('period_start', lang)}
-								<input type="date" bind:value={addStart} max={todayStr} />
+								<DatePicker bind:value={addStart} max={todayStr} {lang} />
 							</label>
 							<label>
 								{t('period_end', lang)}
-								<input type="date" bind:value={addEnd} min={addStart} max={todayStr} />
+								<DatePicker bind:value={addEnd} min={addStart} max={todayStr} {lang} />
 							</label>
 						</div>
 						<div class="add-actions">

src/lib/components/tasks/TaskForm.svelte

@@ -3,6 +3,7 @@
     Flower2, Droplets, Leaf, ShoppingCart, Trash2, Shirt, Brush } from '@lucide/svelte';
   import ProfilePicture from '$lib/components/cospend/ProfilePicture.svelte';
   import Toggle from '$lib/components/Toggle.svelte';
+  import DatePicker from '$lib/components/DatePicker.svelte';
 
   const USERS = ['anna', 'alexander'];
 
@@ -306,7 +307,7 @@
 
   <div class="field">
     <label for="dueDate">Fällig am</label>
-    <input id="dueDate" type="date" bind:value={nextDueDate} required />
+    <DatePicker bind:value={nextDueDate} lang="de" />
   </div>
 
   <div class="field-row">

src/routes/[cospendRoot=cospendRoot]/payments/add/+page.svelte

@@ -12,6 +12,7 @@
   import ImageUpload from '$lib/components/ImageUpload.svelte';
   import SaveFab from '$lib/components/SaveFab.svelte';
   import Toggle from '$lib/components/Toggle.svelte';
+  import DatePicker from '$lib/components/DatePicker.svelte';
 
   let { data, form } = $props();
 
@@ -454,13 +455,8 @@
 
         <div class="form-group">
           <label for="date">{t('payment_date', lang)}</label>
-          <input 
-            type="date" 
-            id="date" 
-            name="date"
-            bind:value={formData.date} 
-            required
-          />
+          <DatePicker bind:value={formData.date} {lang} />
+          <input type="hidden" name="date" value={formData.date} />
           {#if formData.currency !== 'CHF'}
             <small class="help-text">{t('exchange_rate_date', lang)}</small>
           {/if}
@@ -505,13 +501,8 @@
 
             <div class="form-group">
               <label for="recurringStartDate">{t('start_date', lang)}</label>
-              <input 
-                type="date" 
-                id="recurringStartDate" 
-                name="recurringStartDate"
-                bind:value={recurringData.startDate}
-                required
-              />
+              <DatePicker bind:value={recurringData.startDate} {lang} />
+              <input type="hidden" name="recurringStartDate" value={recurringData.startDate} />
             </div>
           </div>
 
@@ -545,13 +536,8 @@
 
           <div class="form-group">
             <label for="recurringEndDate">{t('end_date_optional', lang)}</label>
-            <input 
-              type="date" 
-              id="recurringEndDate" 
-              name="recurringEndDate"
-              bind:value={recurringData.endDate}
-              min={recurringData.startDate}
-            />
+            <DatePicker bind:value={recurringData.endDate} min={recurringData.startDate} {lang} />
+            <input type="hidden" name="recurringEndDate" value={recurringData.endDate} />
             <small class="help-text">{t('end_date_hint', lang)}</small>
           </div>
 

src/routes/[cospendRoot=cospendRoot]/payments/edit/[id]/+page.svelte

@@ -7,6 +7,7 @@
   import FormSection from '$lib/components/FormSection.svelte';
   import ImageUpload from '$lib/components/ImageUpload.svelte';
   import SaveFab from '$lib/components/SaveFab.svelte';
+  import DatePicker from '$lib/components/DatePicker.svelte';
 
   /**
    * @typedef {import('$models/Payment').IPayment & {splits?: import('$models/PaymentSplit').IPaymentSplit[]}} PaymentWithSplits
@@ -42,6 +43,7 @@
   let jsEnhanced = $state(false);
   /** @type {number | null} */
   let originalAmount = $state(null);
+  let paymentDateStr = $state('');
 
   let categoryOptions = $derived(getCategoryOptionsI18n(lang));
 
@@ -169,6 +171,7 @@
         }));
       }
 
+      paymentDateStr = formatDateForInput(loaded.date);
       // Store original amount for comparison to prevent infinite recalculation
       originalAmount = loaded.amount;
       // Set initial lastCalculatedAmount to prevent immediate recalculation on load
@@ -343,6 +346,13 @@
     }
   }
 
+  // Sync date picker string back to payment object
+  $effect(() => {
+    if (payment && paymentDateStr) {
+      payment.date = /** @type {Date} */ (new Date(paymentDateStr + 'T12:00:00'));
+    }
+  });
+
   // Reactive statement for exchange rate fetching
   $effect(() => {
     if (jsEnhanced && payment && payment.currency && payment.currency !== 'CHF' && payment.date && payment.originalAmount) {
@@ -469,13 +479,7 @@
 
           <div class="form-group">
             <label for="date">{t('date', lang)}</label>
-            <input
-              type="date"
-              id="date"
-              value={formatDateForInput(payment.date)}
-              onchange={(e) => { if (payment) payment.date = /** @type {Date} */ (new Date(/** @type {HTMLInputElement} */ (e.target).value)); }}
-              required
-            />
+            <DatePicker bind:value={paymentDateStr} {lang} />
           </div>
         </div>
 

src/routes/[cospendRoot=cospendRoot]/recurring/edit/[id]/+page.svelte

@@ -9,6 +9,7 @@
   import SplitMethodSelector from '$lib/components/cospend/SplitMethodSelector.svelte';
   import UsersList from '$lib/components/cospend/UsersList.svelte';
   import SaveFab from '$lib/components/SaveFab.svelte';
+  import DatePicker from '$lib/components/DatePicker.svelte';
 
   let { data } = $props();
 
@@ -416,12 +417,7 @@
 
           <div class="form-group">
             <label for="startDate">{t('start_date', lang)}</label>
-            <input 
-              type="date" 
-              id="startDate" 
-              bind:value={formData.startDate} 
-              required
-            />
+            <DatePicker bind:value={formData.startDate} {lang} />
           </div>
         </div>
 
@@ -454,11 +450,7 @@
 
         <div class="form-group">
           <label for="endDate">{t('end_date_optional', lang)}</label>
-          <input 
-            type="date" 
-            id="endDate" 
-            bind:value={formData.endDate}
-          />
+          <DatePicker bind:value={formData.endDate} {lang} />
           <div class="help-text">{t('end_date_hint', lang)}</div>
         </div>
 

src/routes/fitness/[history=fitnessHistory]/[id]/+page.svelte

@@ -13,6 +13,7 @@
 	import ExerciseName from '$lib/components/fitness/ExerciseName.svelte';
 	import SetTable from '$lib/components/fitness/SetTable.svelte';
 	import ExercisePicker from '$lib/components/fitness/ExercisePicker.svelte';
+	import DatePicker from '$lib/components/DatePicker.svelte';
 	import FitnessChart from '$lib/components/fitness/FitnessChart.svelte';
 	import { onMount } from 'svelte';
 
@@ -503,7 +504,7 @@
 		<div class="edit-meta">
 			<div class="meta-row">
 				<label for="edit-date">{t('date', lang)}</label>
-				<input id="edit-date" type="date" bind:value={editData.date} />
+				<DatePicker bind:value={editData.date} {lang} />
 			</div>
 			<div class="meta-row">
 				<label for="edit-time">{t('time', lang)}</label>

src/routes/fitness/[measure=fitnessMeasure]/+page.svelte

@@ -5,6 +5,7 @@
 	import { toast } from '$lib/js/toast.svelte';
 	import { confirm } from '$lib/js/confirmDialog.svelte';
 	import SaveFab from '$lib/components/SaveFab.svelte';
+	import DatePicker from '$lib/components/DatePicker.svelte';
 
 	const lang = $derived(detectFitnessLang($page.url.pathname));
 	const measureSlug = $derived(lang === 'en' ? 'measure' : 'messen');
@@ -289,7 +290,7 @@
 	<!-- New measurement form -->
 	<form class="add-form" onsubmit={(e) => { e.preventDefault(); saveMeasurement(); }}>
 		<div class="date-row">
-			<input type="date" bind:value={formDate} class="date-pill" />
+			<DatePicker bind:value={formDate} {lang} />
 		</div>
 
 		<div class="weight-card">
@@ -588,20 +589,6 @@
 		justify-content: center;
 		margin-bottom: 1rem;
 	}
-	.date-pill {
-		background: var(--color-bg-tertiary);
-		border: 1px solid var(--color-border);
-		border-radius: var(--radius-pill);
-		padding: 0.35rem 1rem;
-		font-size: 0.8rem;
-		color: var(--color-text-secondary);
-		cursor: pointer;
-		text-align: center;
-	}
-	.date-pill:focus {
-		outline: none;
-		border-color: var(--color-primary);
-	}
 
 	.weight-card {
 		background: var(--color-surface);

src/routes/fitness/[measure=fitnessMeasure]/edit/[id]/+page.svelte

@@ -6,6 +6,7 @@
 	import { confirm } from '$lib/js/confirmDialog.svelte';
 	import { Trash2 } from '@lucide/svelte';
 	import SaveFab from '$lib/components/SaveFab.svelte';
+	import DatePicker from '$lib/components/DatePicker.svelte';
 
 	const lang = $derived(detectFitnessLang($page.url.pathname));
 	const measureSlug = $derived(lang === 'en' ? 'measure' : 'messen');
@@ -112,7 +113,7 @@
 		<form onsubmit={(e) => { e.preventDefault(); saveMeasurement(); }}>
 			<div class="form-group">
 				<label for="m-date">{t('date', lang)}</label>
-				<input id="m-date" type="date" bind:value={formDate} />
+				<DatePicker bind:value={formDate} {lang} />
 			</div>
 
 			<h3>{t('general', lang)}</h3>