1 files changed, 155 insertions, 0 deletions
diff --git a/src/client/sync/scheduler.ts b/src/client/sync/scheduler.ts
new file mode 100644
index 0000000..72a6e25
--- /dev/null
+++ b/src/client/sync/scheduler.ts
@@ -0,0 +1,155 @@
+import { computeNextSchedule } from "../../shared/fsrs";
+import { db, type LocalCard, type RatingType } from "../db";
+import {
+	localCardRepository,
+	localDeckRepository,
+	localReviewLogRepository,
+} from "../db/repositories";
+import { syncQueue } from "./queue";
+
+export interface SubmitReviewResult {
+	/** The card after the review is applied. */
+	card: LocalCard;
+	/** Snapshot of the card before the review — used by undo. */
+	prevCard: LocalCard;
+	/** The newly created review log id — used by undo. */
+	reviewLogId: string;
+}
+
+/**
+ * Submit a review locally: update card scheduling and create a review log
+ * in IndexedDB. The sync engine will pick up the changes via _synced=false.
+ */
+export async function submitReviewLocal(params: {
+	cardId: string;
+	rating: RatingType;
+	durationMs: number;
+	now?: Date;
+}): Promise<SubmitReviewResult> {
+	const { cardId, rating, durationMs } = params;
+	const now = params.now ?? new Date();
+
+	const card = await localCardRepository.findById(cardId);
+	if (!card) {
+		throw new Error(`Card not found in local database: ${cardId}`);
+	}
+
+	const deck = await localDeckRepository.findById(card.deckId);
+	if (!deck) {
+		throw new Error(`Deck not found in local database: ${card.deckId}`);
+	}
+
+	const prevCard = card;
+	const previousState = card.state;
+
+	const next = computeNextSchedule(card, rating, now);
+
+	const updatedCard = await localCardRepository.updateScheduling(cardId, {
+		state: next.state as LocalCard["state"],
+		due: next.due,
+		stability: next.stability,
+		difficulty: next.difficulty,
+		elapsedDays: next.elapsedDays,
+		scheduledDays: next.scheduledDays,
+		reps: next.reps,
+		lapses: next.lapses,
+		lastReview: next.lastReview,
+	});
+	if (!updatedCard) {
+		throw new Error(`Failed to update card: ${cardId}`);
+	}
+
+	const reviewLog = await localReviewLogRepository.create({
+		cardId,
+		userId: deck.userId,
+		rating,
+		state: previousState,
+		scheduledDays: next.scheduledDays,
+		elapsedDays: next.reviewElapsedDays,
+		reviewedAt: now,
+		durationMs,
+	});
+
+	await syncQueue.notifyChanged();
+
+	return { card: updatedCard, prevCard, reviewLogId: reviewLog.id };
+}
+
+/**
+ * Undo a recent review: restore the previous card state and remove the
+ * just-created review log. Best-effort — if a sync has already pushed the
+ * review, the server still has it.
+ */
+export async function undoReviewLocal(params: {
+	prevCard: LocalCard;
+	reviewLogId: string;
+}): Promise<void> {
+	await db.cards.put({ ...params.prevCard });
+	await localReviewLogRepository.delete(params.reviewLogId);
+	await syncQueue.notifyChanged();
+}
+
+/**
+ * Server-shaped study card. Includes all FSRS fields needed to reconstruct
+ * a LocalCard so we can submit reviews offline.
+ */
+export interface ServerStudyCard {
+	id: string;
+	deckId: string;
+	noteId: string;
+	isReversed: boolean;
+	front: string;
+	back: string;
+	state: number;
+	due: string;
+	stability: number;
+	difficulty: number;
+	elapsedDays: number;
+	scheduledDays: number;
+	reps: number;
+	lapses: number;
+	lastReview: string | null;
+	createdAt: string;
+	updatedAt: string;
+	deletedAt: string | null;
+	syncVersion: number;
+}
+
+/**
+ * Cache study cards into IndexedDB so the scheduler can submit reviews
+ * even when the network drops mid-session. Only cards are cached here —
+ * note types / fields / values come through the regular sync pull.
+ */
+export async function cacheStudyCards(cards: ServerStudyCard[]): Promise<void> {
+	for (const c of cards) {
+		const local: LocalCard = {
+			id: c.id,
+			deckId: c.deckId,
+			noteId: c.noteId,
+			isReversed: c.isReversed,
+			front: c.front,
+			back: c.back,
+			state: c.state as LocalCard["state"],
+			due: new Date(c.due),
+			stability: c.stability,
+			difficulty: c.difficulty,
+			elapsedDays: c.elapsedDays,
+			scheduledDays: c.scheduledDays,
+			reps: c.reps,
+			lapses: c.lapses,
+			lastReview: c.lastReview ? new Date(c.lastReview) : null,
+			createdAt: new Date(c.createdAt),
+			updatedAt: new Date(c.updatedAt),
+			deletedAt: c.deletedAt ? new Date(c.deletedAt) : null,
+			syncVersion: c.syncVersion,
+			_synced: true,
+		};
+
+		// Don't clobber pending local edits (e.g., a review that hasn't
+		// been pushed yet). If the local copy has unsynced changes, skip.
+		const existing = await localCardRepository.findById(c.id);
+		if (existing && !existing._synced) continue;
+
+		await localCardRepository.upsertFromServer(local);
+	}
+}