feat(deck): separate card list from deck detail page

Separate the card list view from the deck learning page to prevent users
from seeing cards they are about to study. The deck detail page now shows
only study statistics with a "Study Now" button and a "View Cards" link.

- Add new DeckCardsPage component at /decks/:deckId/cards for managing cards
- Simplify DeckDetailPage to show deck stats and navigation buttons
- Update routing in App.tsx with proper route ordering
- Add comprehensive tests for both pages

1 files changed, 457 insertions, 0 deletions

diff --git a/src/client/pages/DeckCardsPage.tsx b/src/client/pages/DeckCardsPage.tsx
new file mode 100644
index 0000000..416760a
--- /dev/null
+++ b/src/client/pages/DeckCardsPage.tsx
@@ -0,0 +1,457 @@
+import {
+	faChevronLeft,
+	faFile,
+	faFileImport,
+	faLayerGroup,
+	faPen,
+	faPlus,
+	faTrash,
+} from "@fortawesome/free-solid-svg-icons";
+import { FontAwesomeIcon } from "@fortawesome/react-fontawesome";
+import { useAtomValue, useSetAtom } from "jotai";
+import { Suspense, useMemo, useState, useTransition } from "react";
+import { Link, useParams } from "wouter";
+import { type Card, cardsByDeckAtomFamily, deckByIdAtomFamily } from "../atoms";
+import { CreateNoteModal } from "../components/CreateNoteModal";
+import { DeleteCardModal } from "../components/DeleteCardModal";
+import { DeleteNoteModal } from "../components/DeleteNoteModal";
+import { EditCardModal } from "../components/EditCardModal";
+import { EditNoteModal } from "../components/EditNoteModal";
+import { ErrorBoundary } from "../components/ErrorBoundary";
+import { ImportNotesModal } from "../components/ImportNotesModal";
+import { LoadingSpinner } from "../components/LoadingSpinner";
+
+/** Combined type for display: note group */
+type CardDisplayItem = { type: "note"; noteId: string; cards: Card[] };
+
+const CardStateLabels: Record<number, string> = {
+	0: "New",
+	1: "Learning",
+	2: "Review",
+	3: "Relearning",
+};
+
+const CardStateColors: Record<number, string> = {
+	0: "bg-info/10 text-info",
+	1: "bg-warning/10 text-warning",
+	2: "bg-success/10 text-success",
+	3: "bg-error/10 text-error",
+};
+
+/** Component for displaying a group of cards from the same note */
+function NoteGroupCard({
+	noteId,
+	cards,
+	index,
+	onEditNote,
+	onDeleteNote,
+}: {
+	noteId: string;
+	cards: Card[];
+	index: number;
+	onEditNote: () => void;
+	onDeleteNote: () => void;
+}) {
+	// Use the first card's front/back as preview (normal card takes precedence)
+	const previewCard = cards.find((c) => !c.isReversed) ?? cards[0];
+	if (!previewCard) return null;
+
+	return (
+		<div
+			data-testid="note-group"
+			data-note-id={noteId}
+			className="bg-white rounded-xl border border-border/50 shadow-card hover:shadow-md transition-all duration-200 overflow-hidden"
+			style={{ animationDelay: `${index * 30}ms` }}
+		>
+			{/* Note Header */}
+			<div className="flex items-center justify-between px-5 py-3 border-b border-border/30 bg-ivory/30">
+				<div className="flex items-center gap-2">
+					<FontAwesomeIcon
+						icon={faLayerGroup}
+						className="w-4 h-4 text-muted"
+						aria-hidden="true"
+					/>
+					<span className="text-sm font-medium text-slate">
+						Note ({cards.length} card{cards.length !== 1 ? "s" : ""})
+					</span>
+				</div>
+				<div className="flex items-center gap-1">
+					<button
+						type="button"
+						onClick={onEditNote}
+						className="p-2 text-muted hover:text-slate hover:bg-white rounded-lg transition-colors"
+						title="Edit note"
+					>
+						<FontAwesomeIcon
+							icon={faPen}
+							className="w-4 h-4"
+							aria-hidden="true"
+						/>
+					</button>
+					<button
+						type="button"
+						onClick={onDeleteNote}
+						className="p-2 text-muted hover:text-error hover:bg-error/5 rounded-lg transition-colors"
+						title="Delete note"
+					>
+						<FontAwesomeIcon
+							icon={faTrash}
+							className="w-4 h-4"
+							aria-hidden="true"
+						/>
+					</button>
+				</div>
+			</div>
+
+			{/* Note Content Preview */}
+			<div className="p-5">
+				<div className="grid grid-cols-2 gap-4 mb-4">
+					<div>
+						<span className="text-xs font-medium text-muted uppercase tracking-wide">
+							Front
+						</span>
+						<p className="mt-1 text-slate text-sm line-clamp-2 whitespace-pre-wrap break-words">
+							{previewCard.front}
+						</p>
+					</div>
+					<div>
+						<span className="text-xs font-medium text-muted uppercase tracking-wide">
+							Back
+						</span>
+						<p className="mt-1 text-slate text-sm line-clamp-2 whitespace-pre-wrap break-words">
+							{previewCard.back}
+						</p>
+					</div>
+				</div>
+
+				{/* Cards within this note */}
+				<div className="space-y-2">
+					{cards.map((card) => (
+						<div
+							key={card.id}
+							data-testid="note-card"
+							className="flex items-center gap-3 text-xs p-2 bg-ivory/50 rounded-lg"
+						>
+							<span
+								className={`px-2 py-0.5 rounded-full font-medium ${CardStateColors[card.state] || "bg-muted/10 text-muted"}`}
+							>
+								{CardStateLabels[card.state] || "Unknown"}
+							</span>
+							{card.isReversed ? (
+								<span className="px-2 py-0.5 rounded-full font-medium bg-purple-100 text-purple-700">
+									Reversed
+								</span>
+							) : (
+								<span className="px-2 py-0.5 rounded-full font-medium bg-blue-100 text-blue-700">
+									Normal
+								</span>
+							)}
+							<span className="text-muted">{card.reps} reviews</span>
+							{card.lapses > 0 && (
+								<span className="text-muted">{card.lapses} lapses</span>
+							)}
+						</div>
+					))}
+				</div>
+			</div>
+		</div>
+	);
+}
+
+function DeckHeader({ deckId }: { deckId: string }) {
+	const deck = useAtomValue(deckByIdAtomFamily(deckId));
+
+	return (
+		<div className="mb-8">
+			<h1 className="font-display text-3xl font-semibold text-ink mb-2">
+				{deck.name}
+			</h1>
+			{deck.description && <p className="text-muted">{deck.description}</p>}
+		</div>
+	);
+}
+
+function CardList({
+	deckId,
+	onEditNote,
+	onDeleteNote,
+	onCreateNote,
+}: {
+	deckId: string;
+	onEditNote: (noteId: string) => void;
+	onDeleteNote: (noteId: string) => void;
+	onCreateNote: () => void;
+}) {
+	const cards = useAtomValue(cardsByDeckAtomFamily(deckId));
+
+	// Group cards by note for display
+	const displayItems = useMemo((): CardDisplayItem[] => {
+		const noteGroups = new Map<string, Card[]>();
+
+		for (const card of cards) {
+			const existing = noteGroups.get(card.noteId);
+			if (existing) {
+				existing.push(card);
+			} else {
+				noteGroups.set(card.noteId, [card]);
+			}
+		}
+
+		// Sort note groups by earliest card creation (newest first)
+		const sortedNoteGroups = Array.from(noteGroups.entries()).sort(
+			([, cardsA], [, cardsB]) => {
+				const minA = Math.min(
+					...cardsA.map((c) => new Date(c.createdAt).getTime()),
+				);
+				const minB = Math.min(
+					...cardsB.map((c) => new Date(c.createdAt).getTime()),
+				);
+				return minB - minA; // Newest first
+			},
+		);
+
+		const items: CardDisplayItem[] = [];
+		for (const [noteId, noteCards] of sortedNoteGroups) {
+			// Sort cards within group: normal first, then reversed
+			noteCards.sort((a, b) => {
+				if (a.isReversed === b.isReversed) return 0;
+				return a.isReversed ? 1 : -1;
+			});
+			items.push({ type: "note", noteId, cards: noteCards });
+		}
+
+		return items;
+	}, [cards]);
+
+	if (cards.length === 0) {
+		return (
+			<div className="text-center py-12 bg-white rounded-xl border border-border/50">
+				<div className="w-14 h-14 mx-auto mb-4 bg-ivory rounded-xl flex items-center justify-center">
+					<FontAwesomeIcon
+						icon={faFile}
+						className="w-7 h-7 text-muted"
+						aria-hidden="true"
+					/>
+				</div>
+				<h3 className="font-display text-lg font-medium text-slate mb-2">
+					No cards yet
+				</h3>
+				<p className="text-muted text-sm mb-4">Add notes to start studying</p>
+				<button
+					type="button"
+					onClick={onCreateNote}
+					className="inline-flex items-center gap-2 bg-primary hover:bg-primary-dark text-white font-medium py-2 px-4 rounded-lg transition-all duration-200"
+				>
+					<FontAwesomeIcon
+						icon={faPlus}
+						className="w-5 h-5"
+						aria-hidden="true"
+					/>
+					Add Your First Note
+				</button>
+			</div>
+		);
+	}
+
+	return (
+		<div className="space-y-4">
+			{displayItems.map((item, index) => (
+				<NoteGroupCard
+					key={item.noteId}
+					noteId={item.noteId}
+					cards={item.cards}
+					index={index}
+					onEditNote={() => onEditNote(item.noteId)}
+					onDeleteNote={() => onDeleteNote(item.noteId)}
+				/>
+			))}
+		</div>
+	);
+}
+
+function CardsContent({
+	deckId,
+	onCreateNote,
+	onImportNotes,
+	onEditNote,
+	onDeleteNote,
+}: {
+	deckId: string;
+	onCreateNote: () => void;
+	onImportNotes: () => void;
+	onEditNote: (noteId: string) => void;
+	onDeleteNote: (noteId: string) => void;
+}) {
+	const cards = useAtomValue(cardsByDeckAtomFamily(deckId));
+
+	return (
+		<div className="animate-fade-in">
+			{/* Deck Header */}
+			<ErrorBoundary>
+				<Suspense fallback={<LoadingSpinner />}>
+					<DeckHeader deckId={deckId} />
+				</Suspense>
+			</ErrorBoundary>
+
+			{/* Cards Section */}
+			<div className="flex items-center justify-between mb-6">
+				<h2 className="font-display text-xl font-medium text-slate">
+					Cards <span className="text-muted font-normal">({cards.length})</span>
+				</h2>
+				<div className="flex items-center gap-2">
+					<button
+						type="button"
+						onClick={onImportNotes}
+						className="inline-flex items-center gap-2 border border-border hover:bg-ivory text-slate font-medium py-2 px-4 rounded-lg transition-all duration-200 active:scale-[0.98]"
+					>
+						<FontAwesomeIcon
+							icon={faFileImport}
+							className="w-5 h-5"
+							aria-hidden="true"
+						/>
+						Import CSV
+					</button>
+					<button
+						type="button"
+						onClick={onCreateNote}
+						className="inline-flex items-center gap-2 bg-primary hover:bg-primary-dark text-white font-medium py-2 px-4 rounded-lg transition-all duration-200 active:scale-[0.98]"
+					>
+						<FontAwesomeIcon
+							icon={faPlus}
+							className="w-5 h-5"
+							aria-hidden="true"
+						/>
+						Add Note
+					</button>
+				</div>
+			</div>
+
+			{/* Card List */}
+			<CardList
+				deckId={deckId}
+				onEditNote={onEditNote}
+				onDeleteNote={onDeleteNote}
+				onCreateNote={onCreateNote}
+			/>
+		</div>
+	);
+}
+
+export function DeckCardsPage() {
+	const { deckId } = useParams<{ deckId: string }>();
+	const [, startTransition] = useTransition();
+
+	const reloadCards = useSetAtom(cardsByDeckAtomFamily(deckId || ""));
+
+	const [isCreateModalOpen, setIsCreateModalOpen] = useState(false);
+	const [isImportModalOpen, setIsImportModalOpen] = useState(false);
+	const [editingCard, setEditingCard] = useState<Card | null>(null);
+	const [editingNoteId, setEditingNoteId] = useState<string | null>(null);
+	const [deletingCard, setDeletingCard] = useState<Card | null>(null);
+	const [deletingNoteId, setDeletingNoteId] = useState<string | null>(null);
+
+	const handleCardMutation = () => {
+		startTransition(() => {
+			reloadCards();
+		});
+	};
+
+	if (!deckId) {
+		return (
+			<div className="min-h-screen bg-cream flex items-center justify-center">
+				<div className="text-center">
+					<p className="text-muted mb-4">Invalid deck ID</p>
+					<Link
+						href="/"
+						className="text-primary hover:text-primary-dark font-medium"
+					>
+						Back to decks
+					</Link>
+				</div>
+			</div>
+		);
+	}
+
+	return (
+		<div className="min-h-screen bg-cream">
+			{/* Header */}
+			<header className="bg-white border-b border-border/50">
+				<div className="max-w-4xl mx-auto px-4 py-4">
+					<Link
+						href={`/decks/${deckId}`}
+						className="inline-flex items-center gap-2 text-muted hover:text-slate transition-colors text-sm"
+					>
+						<FontAwesomeIcon
+							icon={faChevronLeft}
+							className="w-4 h-4"
+							aria-hidden="true"
+						/>
+						Back to Deck
+					</Link>
+				</div>
+			</header>
+
+			{/* Main Content */}
+			<main className="max-w-4xl mx-auto px-4 py-8">
+				<ErrorBoundary>
+					<Suspense fallback={<LoadingSpinner />}>
+						<CardsContent
+							deckId={deckId}
+							onCreateNote={() => setIsCreateModalOpen(true)}
+							onImportNotes={() => setIsImportModalOpen(true)}
+							onEditNote={setEditingNoteId}
+							onDeleteNote={setDeletingNoteId}
+						/>
+					</Suspense>
+				</ErrorBoundary>
+			</main>
+
+			{/* Modals */}
+			<CreateNoteModal
+				isOpen={isCreateModalOpen}
+				deckId={deckId}
+				onClose={() => setIsCreateModalOpen(false)}
+				onNoteCreated={handleCardMutation}
+			/>
+
+			<ImportNotesModal
+				isOpen={isImportModalOpen}
+				deckId={deckId}
+				onClose={() => setIsImportModalOpen(false)}
+				onImportComplete={handleCardMutation}
+			/>
+
+			<EditCardModal
+				isOpen={editingCard !== null}
+				deckId={deckId}
+				card={editingCard}
+				onClose={() => setEditingCard(null)}
+				onCardUpdated={handleCardMutation}
+			/>
+
+			<EditNoteModal
+				isOpen={editingNoteId !== null}
+				deckId={deckId}
+				noteId={editingNoteId}
+				onClose={() => setEditingNoteId(null)}
+				onNoteUpdated={handleCardMutation}
+			/>
+
+			<DeleteCardModal
+				isOpen={deletingCard !== null}
+				deckId={deckId}
+				card={deletingCard}
+				onClose={() => setDeletingCard(null)}
+				onCardDeleted={handleCardMutation}
+			/>
+
+			<DeleteNoteModal
+				isOpen={deletingNoteId !== null}
+				deckId={deckId}
+				noteId={deletingNoteId}
+				onClose={() => setDeletingNoteId(null)}
+				onNoteDeleted={handleCardMutation}
+			/>
+		</div>
+	);
+}