feat: 문제집 삭제 + PS/국어 데이터 완전 제거

- DELETE /study-logs/by-prefix: 문제집 삭제 시 관련 StudyLog+ReviewSchedule cascade 삭제
- POST /study-logs/purge-non-math: PS studyLog + 비수학 subject 일괄 삭제
- dashboard/reviews/study-logs 쿼리에 psProblemId:null + subject:'수학' 필터 추가
- 카탈로그: ebook 카드 삭제 버튼 + 경고 confirm + 숨기기/복원
- 대시보드 마운트 시 1회 자동 purge (localStorage flag)

backend/src/dashboard/dashboard.service.ts

@@ -26,6 +26,10 @@ export class DashboardService {
           userId,
           status: ReviewStatus.pending,
           scheduledAt: { lte: now },
+          studyLog: {
+            psProblemId: null,
+            subject: { name: '수학' },
+          },
         },
       }),
       this.prisma.reviewSchedule.count({
@@ -33,10 +37,18 @@ export class DashboardService {
           userId,
           status: ReviewStatus.pending,
           scheduledAt: { gt: now, lte: todayEnd },
+          studyLog: {
+            psProblemId: null,
+            subject: { name: '수학' },
+          },
         },
       }),
       this.prisma.studyLog.findMany({
-        where: { userId },
+        where: {
+          userId,
+          psProblemId: null,
+          subject: { name: '수학' },
+        },
         orderBy: { studiedAt: 'desc' },
         take: 5,
         include: {
@@ -48,12 +60,18 @@ export class DashboardService {
         by: ['result'],
         where: {
           userId,
+          psProblemId: null,
+          subject: { name: '수학' },
           studiedAt: { gte: weekStart },
         },
         _count: { result: true },
       }),
       this.prisma.skillSnapshot.findMany({
-        where: { userId, tagId: { not: null } },
+        where: {
+          userId,
+          tagId: { not: null },
+          tag: { subject: { name: '수학' } },
+        },
         include: {
           tag: {
             select: {

backend/src/reviews/reviews.service.ts

@@ -29,6 +29,10 @@ export class ReviewsService {
         userId,
         status: ReviewStatus.pending,
         scheduledAt: { lte: soon },
+        studyLog: {
+          psProblemId: null,
+          subject: { name: '수학' },
+        },
       },
       include: {
         studyLog: {
@@ -208,6 +212,10 @@ export class ReviewsService {
       where: {
         userId,
         status: { in: [ReviewStatus.done, ReviewStatus.skipped] },
+        studyLog: {
+          psProblemId: null,
+          subject: { name: '수학' },
+        },
       },
       include: {
         studyLog: {
@@ -234,6 +242,10 @@ export class ReviewsService {
       where: {
         userId,
         scheduledAt: { gte: start, lt: end },
+        studyLog: {
+          psProblemId: null,
+          subject: { name: '수학' },
+        },
       },
       select: {
         scheduledAt: true,
@@ -277,6 +289,10 @@ export class ReviewsService {
       where: {
         userId,
         scheduledAt: { gte: start, lt: end },
+        studyLog: {
+          psProblemId: null,
+          subject: { name: '수학' },
+        },
       },
       include: {
         studyLog: {

backend/src/study-logs/study-logs.controller.ts

@@ -2,6 +2,7 @@ import {
   BadRequestException,
   Body,
   Controller,
+  Delete,
   Get,
   Patch,
   Param,
@@ -218,6 +219,19 @@ export class StudyLogsController {
     return this.svc.update(user.id, id, dto);
   }
 
+  @Delete('by-prefix')
+  deleteByPrefix(
+    @CurrentUser() user: AuthUser,
+    @Query('prefix') prefix: string,
+  ) {
+    return this.svc.deleteByPrefix(user.id, prefix);
+  }
+
+  @Post('purge-non-math')
+  purgeNonMath(@CurrentUser() user: AuthUser) {
+    return this.svc.purgeNonMath(user.id);
+  }
+
   @Post('upload-pdf')
   @UseInterceptors(
     FileInterceptor('file', {

backend/src/study-logs/study-logs.service.ts

@@ -288,6 +288,87 @@ export class StudyLogsService {
     });
   }
 
+  async deleteByPrefix(userId: number, prefix: string) {
+    if (!prefix || prefix.length < 2) throw new BadRequestException('prefix too short');
+
+    const logs = await this.prisma.studyLog.findMany({
+      where: { userId, title: { startsWith: prefix } },
+      select: { id: true },
+    });
+    const logIds = logs.map((l) => l.id);
+
+    if (logIds.length === 0) return { deleted: { studyLogs: 0, reviewSchedules: 0 } };
+
+    const result = await this.prisma.$transaction(async (tx) => {
+      const reviews = await tx.reviewSchedule.deleteMany({
+        where: { studyLogId: { in: logIds } },
+      });
+      const studyLogs = await tx.studyLog.deleteMany({
+        where: { id: { in: logIds } },
+      });
+      return { studyLogs: studyLogs.count, reviewSchedules: reviews.count };
+    });
+
+    return { deleted: result };
+  }
+
+  async purgeNonMath(userId: number) {
+    const mathSubject = await this.prisma.subject.findFirst({
+      where: { userId, name: '수학' },
+    });
+
+    return this.prisma.$transaction(async (tx) => {
+      const psLogs = await tx.studyLog.findMany({
+        where: { userId, psProblemId: { not: null } },
+        select: { id: true },
+      });
+      const psLogIds = psLogs.map((l) => l.id);
+
+      let psReviewsDeleted = 0;
+      let psLogsDeleted = 0;
+      if (psLogIds.length > 0) {
+        const r = await tx.reviewSchedule.deleteMany({ where: { studyLogId: { in: psLogIds } } });
+        psReviewsDeleted = r.count;
+        const s = await tx.studyLog.deleteMany({ where: { id: { in: psLogIds } } });
+        psLogsDeleted = s.count;
+      }
+
+      let nonMathReviewsDeleted = 0;
+      let nonMathLogsDeleted = 0;
+      if (mathSubject) {
+        const nonMathLogs = await tx.studyLog.findMany({
+          where: { userId, subjectId: { not: mathSubject.id } },
+          select: { id: true },
+        });
+        const nonMathLogIds = nonMathLogs.map((l) => l.id);
+        if (nonMathLogIds.length > 0) {
+          const r = await tx.reviewSchedule.deleteMany({ where: { studyLogId: { in: nonMathLogIds } } });
+          nonMathReviewsDeleted = r.count;
+          const s = await tx.studyLog.deleteMany({ where: { id: { in: nonMathLogIds } } });
+          nonMathLogsDeleted = s.count;
+        }
+      }
+
+      let nonMathSubjectsDeleted = 0;
+      if (mathSubject) {
+        const s = await tx.subject.deleteMany({
+          where: { userId, id: { not: mathSubject.id } },
+        });
+        nonMathSubjectsDeleted = s.count;
+      }
+
+      return {
+        purged: {
+          psStudyLogs: psLogsDeleted,
+          psReviewSchedules: psReviewsDeleted,
+          nonMathStudyLogs: nonMathLogsDeleted,
+          nonMathReviewSchedules: nonMathReviewsDeleted,
+          nonMathSubjects: nonMathSubjectsDeleted,
+        },
+      };
+    });
+  }
+
   list(
     userId: number,
     opts: {
@@ -300,6 +381,8 @@ export class StudyLogsService {
     return this.prisma.studyLog.findMany({
       where: {
         userId,
+        psProblemId: null,
+        subject: { name: '수학' },
         ...(opts.subjectId && { subjectId: opts.subjectId }),
         ...(opts.tagId && { tagId: opts.tagId }),
       },
@@ -319,7 +402,7 @@ export class StudyLogsService {
 
   async getOne(userId: number, id: number) {
     const log = await this.prisma.studyLog.findFirst({
-      where: { id, userId },
+      where: { id, userId, psProblemId: null },
       include: {
         subject: { select: { id: true, name: true, color: true } },
         tag: { select: { id: true, name: true } },

frontend/src/app/dashboard/page.tsx

@@ -95,6 +95,15 @@ function DashboardBody() {
     setCoachDismissed(window.localStorage.getItem(COACH_DISMISS_KEY) === '1');
   }, []);
 
+  useEffect(() => {
+    const purged = localStorage.getItem('reloop-purged-non-math');
+    if (!purged) {
+      api.post('/study-logs/purge-non-math').then(() => {
+        localStorage.setItem('reloop-purged-non-math', 'true');
+      }).catch(() => {});
+    }
+  }, []);
+
   useEffect(() => {
     let cancelled = false;
 

frontend/src/app/exams/page.tsx

@@ -51,6 +51,19 @@ function saveUploadedPdfs(pdfs: UploadedPdf[]) {
   localStorage.setItem('reloop-uploaded-pdfs', JSON.stringify(pdfs));
 }
 
+function loadHiddenEbooks(): string[] {
+  if (typeof window === 'undefined') return [];
+  try {
+    return JSON.parse(localStorage.getItem('reloop-hidden-ebooks') || '[]');
+  } catch {
+    return [];
+  }
+}
+
+function saveHiddenEbooks(ids: string[]) {
+  localStorage.setItem('reloop-hidden-ebooks', JSON.stringify(ids));
+}
+
 // ─── 메인 페이지 ─────────────────────────────────────────────────────────────
 
 export default function ExamsPage() {
@@ -67,6 +80,7 @@ function ExamsBody() {
 
   const [registeredEbooks, setRegisteredEbooks] = useState<string[]>(loadRegisteredEbooks);
   const [uploadedPdfs, setUploadedPdfs] = useState<UploadedPdf[]>(loadUploadedPdfs);
+  const [hiddenEbooks, setHiddenEbooks] = useState<string[]>(loadHiddenEbooks);
 
   // 모달 상태
   const [showCodeModal, setShowCodeModal] = useState(false);
@@ -95,6 +109,60 @@ function ExamsBody() {
     saveUploadedPdfs(next);
   }
 
+  async function handleDeleteSampleEbook(ebook: EbookMeta) {
+    const confirmed = window.confirm(
+      `'${ebook.title}'을 삭제할까? 이 문제집에서 풀었던 모든 학습 기록과 복습 일정도 함께 삭제돼.`,
+    );
+    if (!confirmed) return;
+
+    try {
+      await api.delete('/study-logs/by-prefix', { params: { prefix: `[${ebook.grade}]` } });
+    } catch {
+      // 서버 에러는 무시하고 로컬 처리는 계속
+    }
+
+    // localStorage 풀이 데이터 삭제
+    if (typeof window !== 'undefined') {
+      const keysToRemove: string[] = [];
+      for (let i = 0; i < localStorage.length; i++) {
+        const key = localStorage.key(i);
+        if (key && key.startsWith(`reloop-ebook-${ebook.id}-`)) {
+          keysToRemove.push(key);
+        }
+      }
+      keysToRemove.forEach((k) => localStorage.removeItem(k));
+    }
+
+    const next = [...hiddenEbooks, ebook.id];
+    setHiddenEbooks(next);
+    saveHiddenEbooks(next);
+    showToast({ message: `'${ebook.title}' 이 삭제됐어.`, variant: 'success', durationMs: 3000 });
+  }
+
+  async function handleDeletePremiumEbook(ebook: EbookMeta) {
+    const confirmed = window.confirm(
+      `'${ebook.title}'을 삭제할까? 이 문제집에서 풀었던 모든 학습 기록과 복습 일정도 함께 삭제돼.`,
+    );
+    if (!confirmed) return;
+
+    try {
+      await api.delete('/study-logs/by-prefix', { params: { prefix: `[${ebook.grade}]` } });
+    } catch {
+      // 무시
+    }
+
+    const next = registeredEbooks.filter((id) => id !== ebook.id);
+    setRegisteredEbooks(next);
+    saveRegisteredEbooks(next);
+    showToast({ message: `'${ebook.title}' 이 삭제됐어.`, variant: 'success', durationMs: 3000 });
+  }
+
+  function handleRestoreAll() {
+    setHiddenEbooks([]);
+    saveHiddenEbooks([]);
+    showToast({ message: '삭제된 문제집이 복원됐어.', variant: 'success', durationMs: 2000 });
+  }
+
   function handleStudyLogCreated() {
     showToast({
       message: '복습 문제가 등록됐어! 캘린더에서 확인해봐.',
@@ -107,6 +175,8 @@ function ExamsBody() {
     .map((id) => PREMIUM_EBOOK_MAP[id])
     .filter(Boolean);
 
+  const visibleSampleEbooks = EBOOK_LIST.filter((e) => !hiddenEbooks.includes(e.id));
+
   return (
     <Wrap>
       <HeaderCard>
@@ -161,7 +231,12 @@ function ExamsBody() {
           </SectionLabel>
           <Grid>
             {premiumEbooks.map((ebook) => (
-              <PremiumEbookCard key={ebook.id} ebook={ebook} router={router} />
+              <PremiumEbookCard
+                key={ebook.id}
+                ebook={ebook}
+                router={router}
+                onDelete={handleDeletePremiumEbook}
+              />
             ))}
           </Grid>
         </>
@@ -188,11 +263,25 @@ function ExamsBody() {
         샘플 문제집
       </SectionLabel>
       <Grid>
-        {EBOOK_LIST.map((ebook) => (
-          <SampleEbookCard key={ebook.id} ebook={ebook} router={router} />
+        {visibleSampleEbooks.map((ebook) => (
+          <SampleEbookCard
+            key={ebook.id}
+            ebook={ebook}
+            router={router}
+            onDelete={handleDeleteSampleEbook}
+          />
         ))}
       </Grid>
 
+      {/* 숨긴 ebook 복원 */}
+      {hiddenEbooks.length > 0 && (
+        <RestoreRow>
+          <RestoreLink type="button" onClick={handleRestoreAll}>
+            삭제된 문제집 {hiddenEbooks.length}개 · 복원하기
+          </RestoreLink>
+        </RestoreRow>
+      )}
+
       {/* 모달들 */}
       {showCodeModal && (
         <CodeModal
@@ -518,12 +607,17 @@ function PdfUploadModal({
 function SampleEbookCard({
   ebook,
   router,
+  onDelete,
 }: {
   ebook: EbookMeta;
   router: ReturnType<typeof useRouter>;
+  onDelete: (ebook: EbookMeta) => void;
 }) {
   return (
     <SampleCard>
+      <DeleteBtn type="button" onClick={() => onDelete(ebook)} title="문제집 삭제">
+        <Icon name="x" size={13} />
+      </DeleteBtn>
       <SampleCardHeader>
         <CardTitle>{ebook.title}</CardTitle>
         <SampleBadge $variant="default">
@@ -556,12 +650,17 @@ function SampleEbookCard({
 function PremiumEbookCard({
   ebook,
   router,
+  onDelete,
 }: {
   ebook: EbookMeta;
   router: ReturnType<typeof useRouter>;
+  onDelete: (ebook: EbookMeta) => void;
 }) {
   return (
     <PremiumCard>
+      <DeleteBtn type="button" onClick={() => onDelete(ebook)} title="문제집 삭제">
+        <Icon name="x" size={13} />
+      </DeleteBtn>
       <SampleCardHeader>
         <CardTitle>{ebook.title}</CardTitle>
         <PremiumBadge>
@@ -748,6 +847,54 @@ const SampleCard = styled(Card)`
   }
 `;
 
+const DeleteBtn = styled.button`
+  position: absolute;
+  top: 10px;
+  right: 10px;
+  width: 24px;
+  height: 24px;
+  border: none;
+  border-radius: 6px;
+  background: rgba(244, 63, 94, 0.0);
+  color: ${theme.color.textMute};
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+  opacity: 0;
+  transition: opacity 0.15s, background 0.15s, color 0.15s;
+  z-index: 2;
+
+  ${SampleCard}:hover & {
+    opacity: 1;
+  }
+
+  &:hover {
+    background: rgba(244, 63, 94, 0.14);
+    color: ${theme.color.danger};
+  }
+`;
+
+const RestoreRow = styled.div`
+  display: flex;
+  justify-content: center;
+  padding: ${theme.space.sm} 0;
+`;
+
+const RestoreLink = styled.button`
+  background: none;
+  border: none;
+  cursor: pointer;
+  font-size: 12px;
+  color: ${theme.color.textMute};
+  text-decoration: underline;
+  padding: 0;
+
+  &:hover {
+    color: ${theme.color.textSub};
+  }
+`;
+
 const PremiumCard = styled(SampleCard)`
   background:
     radial-gradient(circle at top right, rgba(245, 158, 11, 0.15), transparent 50%),