fix undo bug

src/lib/deck-types.ts

···
 	oracleId: OracleId,
 	section: Section,
 	quantity = 1,
+	tags: string[] = [],
 ): Deck {
 	const existingCard = findCardInSection(deck, scryfallId, section);
 
···
 
 	return {
 		...deck,
-		cards: [
-			...deck.cards,
-			{ scryfallId, oracleId, quantity, section, tags: [] },
-		],
+		cards: [...deck.cards, { scryfallId, oracleId, quantity, section, tags }],
 		updatedAt: new Date().toISOString(),
 	};
 }

src/routes/profile/$did/deck/$rkey/index.tsx

···
 import { type DragEndEvent, useDndMonitor } from "@dnd-kit/core";
 import { useSuspenseQuery } from "@tanstack/react-query";
 import { createFileRoute, Link } from "@tanstack/react-router";
-import { useCallback, useMemo, useState } from "react";
+import { useCallback, useMemo, useRef, useState } from "react";
 import { ErrorBoundary } from "react-error-boundary";
 import { toast } from "sonner";
 import { CardDragOverlay } from "@/components/deck/CardDragOverlay";
···
 	);
 	const deck = deckRecord.deck;
 
+	// Ref to always have fresh deck state (avoids stale closures in toast callbacks)
+	const deckRef = useRef(deck);
+	deckRef.current = deck;
+
 	const [groupBy, setGroupBy] = usePersistedState<GroupBy>(
 		"deckbelcher:viewConfig:groupBy",
 		"typeAndTags",
···
 	);
 
 	// Helper to update deck via mutation
-	const updateDeck = async (updater: (prev: Deck) => Deck) => {
-		if (!isOwner) return;
-		const updated = updater(deck);
-		await mutation.mutateAsync(updated);
-	};
+	// Uses deckRef to avoid stale closures in async callbacks (e.g., toast undo)
+	const updateDeck = useCallback(
+		async (updater: (prev: Deck) => Deck) => {
+			if (!isOwner) return;
+			const updated = updater(deckRef.current);
+			await mutation.mutateAsync(updated);
+		},
+		[isOwner, mutation],
+	);
 
 	// Highlight cards that were changed - clear after paint so it can trigger again
 	const handleCardsChanged = (changedIds: Set<ScryfallId>) => {
···
 				// Update to success with undo action
 				toast.success("Card removed from deck", {
 					id: toastId,
+					duration: 10000,
 					action: {
 						label: "Undo",
 						onClick: () => {
 							toast.promise(
-								updateDeck((prev) => ({
-									...prev,
-									cards: [...prev.cards, cardToDelete],
-								})),
+								updateDeck((prev) =>
+									addCardToDeck(
+										prev,
+										cardToDelete.scryfallId,
+										cardToDelete.oracleId,
+										cardToDelete.section as Section,
+										cardToDelete.quantity,
+										cardToDelete.tags ?? [],
+									),
+								),
 								{
 									loading: "Undoing...",
 									success: "Card restored",
···
 					if (cardToDelete) {
 						toast.success("Card removed from deck", {
 							id: toastId,
+							duration: 10000,
 							action: {
 								label: "Undo",
 								onClick: () => {
-									// Re-insert the exact card that was deleted
 									toast.promise(
-										updateDeck((prev) => ({
-											...prev,
-											cards: [...prev.cards, cardToDelete],
-										})),
+										updateDeck((prev) =>
+											addCardToDeck(
+												prev,
+												cardToDelete.scryfallId,
+												cardToDelete.oracleId,
+												cardToDelete.section as Section,
+												cardToDelete.quantity,
+												cardToDelete.tags ?? [],
+											),
+										),
 										{
 											loading: "Undoing...",
 											success: "Card restored",

todos.md

···
 
 ## Bugs
 
-### Delete undo adds N+1 copies
-- **Location**: Deck editor undo logic
-- **Issue**: Undoing a card deletion adds N+1 of the card as independent copies instead of restoring the original single entry
-- **Repro**: Delete a card with qty 4, undo, observe 5 separate entries
-
 ### Bare regex for name search doesn't work
 - **Location**: `src/lib/search/parser.ts`, `parseNameExpr()`
 - **Issue**: `/goblin.*king/i` syntax is parsed but not matched correctly for bare name searches (works in field values like `o:/regex/`)
···
 ## Refactoring (Technical Debt)
 
 ### High Priority
+
+#### Deck editor: Replace ref with reducer pattern
+- **Location**: `src/routes/profile/$did/deck/$rkey/index.tsx`
+- **Issue**: Currently uses `deckRef` to avoid stale closures in toast undo callbacks. This is a band-aid fix.
+- **Better approach**: Use `useReducer` for local deck state with explicit actions (`ADD_CARD`, `REMOVE_CARD`, etc.)
+- **Benefits**: Natural fit for undo/redo (action history), integrates well with Immer, clearer mental model
+- **Effort**: Medium
 
 #### Reduce computeManaSymbolsVsSources complexity
 - **Location**: `src/lib/deck-stats.ts:327-502` (176 lines)