fix: always separate completed checklist items from active list

Completed items now consistently appear below unchecked items in both
the editor and the note card preview. Replaces the flaky two-state
hide/show toggle with a simple expand/collapse for the done section.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/components/Checklist.svelte

@@ -20,11 +20,10 @@
 	let { content, onChange }: Props = $props();
 
 	let items = $state<ChecklistItem[]>(parseChecklist(content));
-	let hideCompleted = $state(false);
-	let showDoneSection = $state(false);
+	let doneExpanded = $state(false);
 	const flipDurationMs = 150;
 
-	let activeItems = $derived(hideCompleted ? items.filter((i) => !i.checked) : items);
+	let activeItems = $derived(items.filter((i) => !i.checked));
 	let doneItems = $derived(items.filter((i) => i.checked));
 	let doneCount = $derived(doneItems.length);
 
@@ -103,11 +102,12 @@
 	}
 
 	function handleDndConsider(e: CustomEvent<DndEvent<ChecklistItem>>) {
-		items = e.detail.items;
+		// Merge reordered active items with done items
+		items = [...e.detail.items, ...items.filter((i) => i.checked)];
 	}
 
 	function handleDndFinalize(e: CustomEvent<DndEvent<ChecklistItem>>) {
-		items = e.detail.items;
+		items = [...e.detail.items, ...items.filter((i) => i.checked)];
 		emitChange();
 	}
 </script>
@@ -164,24 +164,15 @@
 	{#if doneCount > 0}
 		<div class="mt-2 border-t border-[var(--border-subtle)] pt-2">
 			<button
-				onclick={() => {
-					if (!hideCompleted) {
-						hideCompleted = true;
-						showDoneSection = false;
-					} else {
-						showDoneSection = !showDoneSection;
-					}
-				}}
+				onclick={() => (doneExpanded = !doneExpanded)}
 				class="flex items-center gap-1 text-xs text-[var(--text-muted)] hover:text-[var(--text)]"
 				data-testid="checklist-toggle-done"
 			>
-				<ChevronRight class="h-3 w-3 transition-transform duration-150 {hideCompleted && showDoneSection ? 'rotate-90' : ''}" />
+				<ChevronRight class="h-3 w-3 transition-transform duration-150 {doneExpanded ? 'rotate-90' : ''}" />
 				{doneCount} done
 			</button>
 
-			{#if !hideCompleted}
-				<!-- Completed items are inline in the main list, toggle hides them -->
-			{:else if showDoneSection}
+			{#if doneExpanded}
 				<div class="mt-1 space-y-1 pl-5" data-testid="checklist-done-section">
 					{#each doneItems as item (item.id)}
 						<div class="flex items-center gap-2">

src/lib/components/NoteCard.svelte

@@ -40,6 +40,10 @@
 			: []
 	);
 
+	const activeChecklistItems = $derived(checklistItems.filter(i => !i.checked));
+	const doneChecklistItems = $derived(checklistItems.filter(i => i.checked));
+	const sortedChecklistItems = $derived([...activeChecklistItems, ...doneChecklistItems]);
+
 	function stop(fn: () => void) {
 		return (e: Event) => {
 			e.stopPropagation();
@@ -47,19 +51,16 @@
 		};
 	}
 
-	function toggleChecklistItem(index: number) {
+	function toggleChecklistItem(item: ChecklistItem) {
 		const lines = note.content.split('\n');
-		let checkIndex = 0;
 		for (let i = 0; i < lines.length; i++) {
 			const line = lines[i];
-			if (line.startsWith('- [x] ') || line.startsWith('- [ ] ')) {
-				if (checkIndex === index) {
-					lines[i] = line.startsWith('- [x] ')
-						? `- [ ] ${line.slice(6)}`
-						: `- [x] ${line.slice(6)}`;
-					break;
-				}
-				checkIndex++;
+			const text = line.replace(/^- \[[ x]\] /, '');
+			if (text === item.text && line.startsWith(item.checked ? '- [x] ' : '- [ ] ')) {
+				lines[i] = item.checked
+					? `- [ ] ${text}`
+					: `- [x] ${text}`;
+				break;
 			}
 		}
 		updateNote(note.id, { content: lines.join('\n') });
@@ -93,12 +94,12 @@
 
 	{#if note.checklistMode && checklistItems.length > 0}
 		<ul class="space-y-1" data-testid="note-checklist-preview">
-			{#each checklistItems.slice(0, 8) as item, index}
+			{#each sortedChecklistItems.slice(0, 8) as item}
 				<li class="flex items-center gap-2 text-sm {item.checked ? 'text-[var(--text-muted)] line-through' : 'text-[var(--text)]'}">
 					<input
 						type="checkbox"
 						checked={item.checked}
-						onclick={(e) => { e.stopPropagation(); toggleChecklistItem(index); }}
+						onclick={(e) => { e.stopPropagation(); toggleChecklistItem(item); }}
 						class="h-3.5 w-3.5 rounded border-[var(--border-subtle)] text-[var(--primary)] cursor-pointer"
 						data-testid="card-checklist-checkbox"
 					/>