feat(study): enforce newCardsPerDay limit in study API

Split due card fetching into new cards and review cards, applying
the deck's newCardsPerDay limit to new cards while leaving review
cards unrestricted. New cards are placed before review cards in
the response.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

4 files changed, 134 insertions, 63 deletions

diff --git a/src/server/repositories/card.test.ts b/src/server/repositories/card.test.ts
index b492fd7..1ed31c7 100644
--- a/src/server/repositories/card.test.ts
+++ b/src/server/repositories/card.test.ts
@@ -114,6 +114,8 @@ function createMockCardRepo(): CardRepository {
 		countDueCards: vi.fn(),
 		findDueCardsWithNoteData: vi.fn(),
 		findDueCardsForStudy: vi.fn(),
+		findDueNewCardsForStudy: vi.fn(),
+		findDueReviewCardsForStudy: vi.fn(),
 		updateFSRSFields: vi.fn(),
 	};
 }
diff --git a/src/server/repositories/card.ts b/src/server/repositories/card.ts
index 2f14149..6202267 100644
--- a/src/server/repositories/card.ts
+++ b/src/server/repositories/card.ts
@@ -1,4 +1,4 @@
-import { and, eq, isNull, lt, sql } from "drizzle-orm";
+import { and, eq, isNull, lt, lte, ne, sql } from "drizzle-orm";
 import { getEndOfStudyDayBoundary } from "../../shared/date.js";
 import { db } from "../db/index.js";
 import {
@@ -263,69 +263,49 @@ export const cardRepository: CardRepository = {
 		limit: number,
 	): Promise<CardForStudy[]> {
 		const dueCards = await this.findDueCards(deckId, now, limit);
+		return enrichCardsForStudy(dueCards);
+	},
 
-		const cardsForStudy: CardForStudy[] = [];
-
-		for (const card of dueCards) {
-			// Fetch note to get noteTypeId
-			const noteResult = await db
-				.select()
-				.from(notes)
-				.where(and(eq(notes.id, card.noteId), isNull(notes.deletedAt)));
-
-			const note = noteResult[0];
-			if (!note) {
-				// Note was deleted, skip this card
-				continue;
-			}
-
-			// Fetch note type for templates
-			const noteTypeResult = await db
-				.select({
-					frontTemplate: noteTypes.frontTemplate,
-					backTemplate: noteTypes.backTemplate,
-				})
-				.from(noteTypes)
-				.where(
-					and(eq(noteTypes.id, note.noteTypeId), isNull(noteTypes.deletedAt)),
-				);
-
-			const noteType = noteTypeResult[0];
-			if (!noteType) {
-				// Note type was deleted, skip this card
-				continue;
-			}
-
-			// Fetch field values with their field names
-			const fieldValuesWithNames = await db
-				.select({
-					fieldName: noteFieldTypes.name,
-					value: noteFieldValues.value,
-				})
-				.from(noteFieldValues)
-				.innerJoin(
-					noteFieldTypes,
-					eq(noteFieldValues.noteFieldTypeId, noteFieldTypes.id),
-				)
-				.where(eq(noteFieldValues.noteId, card.noteId));
-
-			// Convert to name-value map
-			const fieldValuesMap: Record<string, string> = {};
-			for (const fv of fieldValuesWithNames) {
-				fieldValuesMap[fv.fieldName] = fv.value;
-			}
-
-			cardsForStudy.push({
-				...card,
-				noteType: {
-					frontTemplate: noteType.frontTemplate,
-					backTemplate: noteType.backTemplate,
-				},
-				fieldValuesMap,
-			});
-		}
+	async findDueNewCardsForStudy(
+		deckId: string,
+		now: Date,
+		limit: number,
+	): Promise<CardForStudy[]> {
+		const result = await db
+			.select()
+			.from(cards)
+			.where(
+				and(
+					eq(cards.deckId, deckId),
+					isNull(cards.deletedAt),
+					lte(cards.due, now),
+					eq(cards.state, CardState.New),
+				),
+			)
+			.orderBy(cards.due)
+			.limit(limit);
+		return enrichCardsForStudy(result);
+	},
 
-		return cardsForStudy;
+	async findDueReviewCardsForStudy(
+		deckId: string,
+		now: Date,
+		limit: number,
+	): Promise<CardForStudy[]> {
+		const result = await db
+			.select()
+			.from(cards)
+			.where(
+				and(
+					eq(cards.deckId, deckId),
+					isNull(cards.deletedAt),
+					lte(cards.due, now),
+					ne(cards.state, CardState.New),
+				),
+			)
+			.orderBy(cards.due)
+			.limit(limit);
+		return enrichCardsForStudy(result);
 	},
 
 	async updateFSRSFields(
@@ -369,3 +349,62 @@ export const cardRepository: CardRepository = {
 		return result[0];
 	},
 };
+
+async function enrichCardsForStudy(dueCards: Card[]): Promise<CardForStudy[]> {
+	const cardsForStudy: CardForStudy[] = [];
+
+	for (const card of dueCards) {
+		const noteResult = await db
+			.select()
+			.from(notes)
+			.where(and(eq(notes.id, card.noteId), isNull(notes.deletedAt)));
+
+		const note = noteResult[0];
+		if (!note) {
+			continue;
+		}
+
+		const noteTypeResult = await db
+			.select({
+				frontTemplate: noteTypes.frontTemplate,
+				backTemplate: noteTypes.backTemplate,
+			})
+			.from(noteTypes)
+			.where(
+				and(eq(noteTypes.id, note.noteTypeId), isNull(noteTypes.deletedAt)),
+			);
+
+		const noteType = noteTypeResult[0];
+		if (!noteType) {
+			continue;
+		}
+
+		const fieldValuesWithNames = await db
+			.select({
+				fieldName: noteFieldTypes.name,
+				value: noteFieldValues.value,
+			})
+			.from(noteFieldValues)
+			.innerJoin(
+				noteFieldTypes,
+				eq(noteFieldValues.noteFieldTypeId, noteFieldTypes.id),
+			)
+			.where(eq(noteFieldValues.noteId, card.noteId));
+
+		const fieldValuesMap: Record<string, string> = {};
+		for (const fv of fieldValuesWithNames) {
+			fieldValuesMap[fv.fieldName] = fv.value;
+		}
+
+		cardsForStudy.push({
+			...card,
+			noteType: {
+				frontTemplate: noteType.frontTemplate,
+				backTemplate: noteType.backTemplate,
+			},
+			fieldValuesMap,
+		});
+	}
+
+	return cardsForStudy;
+}
diff --git a/src/server/repositories/review-log.ts b/src/server/repositories/review-log.ts
index c8950d6..591c647 100644
--- a/src/server/repositories/review-log.ts
+++ b/src/server/repositories/review-log.ts
@@ -1,5 +1,6 @@
+import { and, eq, gte, sql } from "drizzle-orm";
 import { db } from "../db/index.js";
-import { reviewLogs } from "../db/schema.js";
+import { CardState, cards, reviewLogs } from "../db/schema.js";
 import type { ReviewLog, ReviewLogRepository } from "./types.js";
 
 export const reviewLogRepository: ReviewLogRepository = {
@@ -29,4 +30,22 @@ export const reviewLogRepository: ReviewLogRepository = {
 		}
 		return reviewLog;
 	},
+
+	async countTodayNewCardReviews(deckId: string, now: Date): Promise<number> {
+		const startOfDay = new Date(now);
+		startOfDay.setHours(0, 0, 0, 0);
+
+		const result = await db
+			.select({ count: sql<number>`count(distinct ${reviewLogs.cardId})::int` })
+			.from(reviewLogs)
+			.innerJoin(cards, eq(reviewLogs.cardId, cards.id))
+			.where(
+				and(
+					eq(cards.deckId, deckId),
+					eq(reviewLogs.state, CardState.New),
+					gte(reviewLogs.reviewedAt, startOfDay),
+				),
+			);
+		return result[0]?.count ?? 0;
+	},
 };
diff --git a/src/server/repositories/types.ts b/src/server/repositories/types.ts
index cb3a287..47fb68f 100644
--- a/src/server/repositories/types.ts
+++ b/src/server/repositories/types.ts
@@ -158,6 +158,16 @@ export interface CardRepository {
 		now: Date,
 		limit: number,
 	): Promise<CardForStudy[]>;
+	findDueNewCardsForStudy(
+		deckId: string,
+		now: Date,
+		limit: number,
+	): Promise<CardForStudy[]>;
+	findDueReviewCardsForStudy(
+		deckId: string,
+		now: Date,
+		limit: number,
+	): Promise<CardForStudy[]>;
 	updateFSRSFields(
 		id: string,
 		deckId: string,
@@ -198,6 +208,7 @@ export interface ReviewLogRepository {
 		elapsedDays: number;
 		durationMs?: number | null;
 	}): Promise<ReviewLog>;
+	countTodayNewCardReviews(deckId: string, now: Date): Promise<number>;
 }
 
 export interface NoteType {