feat: 알고리즘 개선 + 태그 활용 강화

알고리즘: - SkillSnapshot 필드 분리: s0(기억강도 0~1) + easeFactor(EF 1.3~4.0) - SM-2에 intensity 배율 반영 (strict×0.7, moderate×1.0, relaxed×1.4) - 망각곡선 보정 통합: SM-2 간격 후 예상 P<30%면 안전 간격으로 축소 - SM-2에서도 s0(기억강도) 업데이트하여 두 모델이 항상 동기화 태그 활용: - 복습 세션에 태그 필터 칩 (특정 단원만 집중 복습) - 복습 완료 요약에 태그별 통계 (어려움/보통/쉬움 카운트) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-17 17:38:42 +09:00
parent 85caf9b71d
commit eeb94db8e7
6 changed files with 238 additions and 30 deletions
--- a/backend/prisma/schema.prisma
+++ b/backend/prisma/schema.prisma
@@ -381,7 +381,10 @@ model SkillSnapshot {
  tagId  Int?
  tag    Tag? @relation(fields: [tagId], references: [id], onDelete: SetNull)

+  /// 기억 강도 (0~1). 망각곡선에서 사용.
  s0            Float
+  /// SM-2 Ease Factor (1.3~4.0). null이면 SM-2 미사용 태그.
+  easeFactor    Float?
  lastUpdatedAt DateTime @default(now())
  sampleCount   Int      @default(0)

--- a/backend/src/forget/persona-forget.service.ts
+++ b/backend/src/forget/persona-forget.service.ts
@@ -52,18 +52,32 @@ export const MIN_EF = 1.3;

 export type SelfDifficulty = 'hard' | 'medium' | 'easy';

+/** SM-2 간격에 곱하는 학습 강도 배율 */
+export const INTENSITY_SM2_FACTOR: Record<ReviewIntensity, number> = {
+  strict: 0.7,
+  moderate: 1.0,
+  relaxed: 1.4,
+};
+
 export interface SM2Input {
  iteration: number;
  selfDifficulty: SelfDifficulty;
  currentEF: number;
  persona: Persona;
+  intensity?: ReviewIntensity;
+  /** 현재 기억 강도 (0~1). 망각곡선 보정에 사용 */
+  currentS0?: number;
+  /** 문제 난이도 (0~1). 망각곡선 보정에 사용 */
+  difficulty?: number;
  now?: Date;
 }

 export interface SM2Output {
  intervalDays: number;
  newEF: number;
+  newS0: number;
  scheduledAt: Date;
+  predictedP: number | null;
 }

 export const INTENSITY_THRESHOLD: Record<ReviewIntensity, number> = {
@@ -238,8 +252,9 @@ export class PersonaForgetService {
    const { iteration, selfDifficulty, currentEF, persona } = input;
    const now = input.now ?? new Date();
    const pf = PERSONA_FACTOR[persona] ?? 1.0;
+    const intensityFactor = INTENSITY_SM2_FACTOR[input.intensity ?? 'moderate'];

-    // EF 업데이트
+    // ── EF 업데이트 ──
    let newEF = currentEF;
    if (selfDifficulty === 'hard') {
      newEF = Math.max(MIN_EF, currentEF - 0.3);
@@ -247,22 +262,51 @@ export class PersonaForgetService {
      newEF = Math.max(MIN_EF, currentEF + 0.15);
    }

-    // 간격 계산
+    // ── S0 (기억 강도) 업데이트 ──
+    const prevS0 = input.currentS0 ?? DEFAULT_INITIAL_S0;
+    const resultForS0: StudyResult =
+      selfDifficulty === 'hard' ? 'incorrect' : selfDifficulty === 'easy' ? 'correct' : 'partial';
+    const newS0 = this.updateS0({ previousS0: prevS0, result: resultForS0 });
+
+    // ── SM-2 간격 계산 ──
    let intervalDays: number;
    if (selfDifficulty === 'hard') {
      intervalDays = 1;
    } else if (iteration <= 0) {
-      // 최초 학습 — selfDifficulty 에 따라 차등
      if (selfDifficulty === 'medium') {
-        intervalDays = Math.round(3 * pf);
+        intervalDays = Math.round(3 * pf * intensityFactor);
      } else {
-        // easy
-        intervalDays = Math.round(7 * pf);
+        intervalDays = Math.round(7 * pf * intensityFactor);
      }
    } else if (iteration === 1) {
-      intervalDays = Math.round(6 * pf);
+      intervalDays = Math.round(6 * pf * intensityFactor);
    } else {
-      intervalDays = Math.round(6 * Math.pow(newEF, iteration - 1) * pf);
+      intervalDays = Math.round(6 * Math.pow(newEF, iteration - 1) * pf * intensityFactor);
+    }
+
+    // ── 망각곡선 보정 ──
+    // SM-2가 계산한 간격 뒤의 예상 기억 강도를 시뮬레이션.
+    // 예상 P가 너무 낮으면 간격을 줄여서 안전장치 역할.
+    const lambda = PERSONA_LAMBDA[persona];
+    const D = input.difficulty ?? 0.5;
+    let predictedP: number | null = null;
+
+    if (selfDifficulty !== 'hard' && intervalDays > 1) {
+      const futureS = newS0 * Math.exp(-lambda * intervalDays);
+      predictedP = this.sigmoid(this.k * (futureS - D));
+
+      // 예상 정답 확률이 30% 이하로 떨어지면 간격을 축소
+      if (predictedP < 0.3 && intervalDays > 2) {
+        // 정답 확률 50%가 되는 시점으로 축소
+        const target50 = D; // sigmoid(k * (s - D)) = 0.5 ⟹ s = D
+        if (target50 > 0 && target50 < newS0) {
+          const safeDays = Math.max(1, Math.floor(-(1 / lambda) * Math.log(target50 / newS0)));
+          intervalDays = Math.min(intervalDays, safeDays);
+        }
+        // 재계산된 P
+        const adjS = newS0 * Math.exp(-lambda * intervalDays);
+        predictedP = this.sigmoid(this.k * (adjS - D));
+      }
    }

    intervalDays = Math.max(1, Math.min(MAX_INTERVAL_DAYS, intervalDays));
@@ -270,7 +314,9 @@ export class PersonaForgetService {
    return {
      intervalDays,
      newEF,
+      newS0,
      scheduledAt: addDays(now, intervalDays),
+      predictedP,
    };
  }

--- a/backend/src/me/me.service.ts
+++ b/backend/src/me/me.service.ts
@@ -124,26 +124,29 @@ export class MeService {
    for (const review of pendingReviews) {
      const { tagId, difficulty, baseCorrectRate } = review.studyLog;

-      let snap: { s0: number; lastUpdatedAt: Date } | null = null;
+      let snap: { s0: number; easeFactor: number | null; lastUpdatedAt: Date } | null = null;
      if (tagId !== null) {
        snap = await this.prisma.skillSnapshot.findUnique({
          where: { userId_tagId: { userId, tagId } },
-          select: { s0: true, lastUpdatedAt: true },
+          select: { s0: true, easeFactor: true, lastUpdatedAt: true },
        });
      }

-      // SM-2 경로: SkillSnapshot.s0 가 EF 범위(1.3 ~ 4.0)에 있는 경우
-      if (snap !== null && snap.s0 >= 1.3 && snap.s0 <= 4.0) {
+      // SM-2 경로: easeFactor가 있으면 SM-2
+      if (snap !== null && snap.easeFactor !== null && snap.easeFactor !== undefined) {
        const sm2 = this.forget.sm2Schedule({
          iteration: review.iteration,
          selfDifficulty: 'medium',
-          currentEF: snap.s0,
+          currentEF: snap.easeFactor,
          persona: newPersona,
+          intensity: newIntensity,
+          currentS0: snap.s0,
+          difficulty: baseCorrectRate != null ? 1 - baseCorrectRate : difficulty,
          now: review.createdAt,
        });
        await this.prisma.reviewSchedule.update({
          where: { id: review.id },
-          data: { scheduledAt: sm2.scheduledAt },
+          data: { scheduledAt: sm2.scheduledAt, predictedP: sm2.predictedP },
        });
      } else {
        // 망각곡선 경로
--- a/backend/src/reviews/reviews.service.ts
+++ b/backend/src/reviews/reviews.service.ts
@@ -152,14 +152,16 @@ export class ReviewsService {
      const nextIteration = (lastDone?.iteration ?? flipped.iteration) + 1;

      if (selfDifficulty) {
-        // ── SM-2 하이브리드 경로 ──────────────────────────────────────────────
+        // ── SM-2 하이브리드 + 망각곡선 보정 ──────────────────────────────────
        let currentEF = DEFAULT_EF;
+        let currentS0 = 0.3;
        if (review.studyLog.tagId) {
          const snap = await tx.skillSnapshot.findUnique({
            where: { userId_tagId: { userId, tagId: review.studyLog.tagId } },
          });
-          if (snap && snap.s0 >= 1.3 && snap.s0 <= 4.0) {
-            currentEF = snap.s0;
+          if (snap) {
+            currentEF = snap.easeFactor ?? DEFAULT_EF;
+            currentS0 = snap.s0;
          }
        }

@@ -168,24 +170,28 @@ export class ReviewsService {
          selfDifficulty,
          currentEF,
          persona: user.persona,
+          intensity: user.reviewIntensity,
+          currentS0,
+          difficulty: D,
          now,
        });
        nextScheduledAt = sm2.scheduledAt;
-        nextPredictedP = null;
+        nextPredictedP = sm2.predictedP;

-        // EF 업데이트: tagId 있는 경우 저장
        if (review.studyLog.tagId) {
          await tx.skillSnapshot.upsert({
            where: { userId_tagId: { userId, tagId: review.studyLog.tagId } },
            create: {
              userId,
              tagId: review.studyLog.tagId,
-              s0: sm2.newEF,
+              s0: sm2.newS0,
+              easeFactor: sm2.newEF,
              lastUpdatedAt: now,
              sampleCount: nextIteration,
            },
            update: {
-              s0: sm2.newEF,
+              s0: sm2.newS0,
+              easeFactor: sm2.newEF,
              lastUpdatedAt: now,
              sampleCount: nextIteration,
            },
--- a/backend/src/study-logs/study-logs.service.ts
+++ b/backend/src/study-logs/study-logs.service.ts
@@ -688,15 +688,16 @@ export class StudyLogsService {
    let predictedP: number | null = null;

    if (input.selfDifficulty) {
-      // ── SM-2 하이브리드 경로 ────────────────────────────────────────────────
-      // tagId 있으면 SkillSnapshot.s0 에서 EF 로드 (EF 범위 1.3~4.0 이면 사용)
+      // ── SM-2 하이브리드 + 망각곡선 보정 ─────────────────────────────────────
      let currentEF = DEFAULT_EF;
+      let currentS0 = 0.3;
      if (input.tagId) {
        const snap = await tx.skillSnapshot.findUnique({
          where: { userId_tagId: { userId, tagId: input.tagId } },
        });
-        if (snap && snap.s0 >= 1.3 && snap.s0 <= 4.0) {
-          currentEF = snap.s0;
+        if (snap) {
+          currentEF = snap.easeFactor ?? DEFAULT_EF;
+          currentS0 = snap.s0;
        }
      }

@@ -705,24 +706,29 @@ export class StudyLogsService {
        selfDifficulty: input.selfDifficulty,
        currentEF,
        persona: user.persona,
+        intensity: user.reviewIntensity,
+        currentS0,
+        difficulty: D,
        now,
      });
      scheduledAt = sm2.scheduledAt;
-      predictedP = null;
+      predictedP = sm2.predictedP;

-      // EF 저장: tagId 있는 경우 SkillSnapshot.s0 에 EF 값으로 upsert
+      // EF와 S0를 분리 저장
      if (input.tagId) {
        await tx.skillSnapshot.upsert({
          where: { userId_tagId: { userId, tagId: input.tagId } },
          create: {
            userId,
            tagId: input.tagId,
-            s0: sm2.newEF,
+            s0: sm2.newS0,
+            easeFactor: sm2.newEF,
            lastUpdatedAt: now,
            sampleCount: 1,
          },
          update: {
-            s0: sm2.newEF,
+            s0: sm2.newS0,
+            easeFactor: sm2.newEF,
            lastUpdatedAt: now,
            sampleCount: { increment: 1 },
          },
--- a/frontend/src/app/review/page.tsx
+++ b/frontend/src/app/review/page.tsx
@@ -102,6 +102,7 @@ export default function ReviewPage() {
  const [penColor, setPenColor] = useState<PenColor>('#ef4444');
  const [clearSignal, setClearSignal] = useState(0);
  const [tagPromptFor, setTagPromptFor] = useState<{ studyLogId: number; tagId: number | null } | null>(null);
+  const [tagFilter, setTagFilter] = useState<string | null>(null);

  useEffect(() => {
    if (typeof window === 'undefined') return;
@@ -170,7 +171,22 @@ export default function ReviewPage() {
    void load();
  }, [load]);

-  const currentItem = queue?.[0] ?? null;
+  const availableTags = useMemo(() => {
+    if (!queue) return [];
+    const tags = new Map<string, string>();
+    for (const item of queue) {
+      const tag = item.studyLog.tag;
+      if (tag) tags.set(String(tag.id), tag.name);
+    }
+    return Array.from(tags.entries()).map(([id, name]) => ({ id, name }));
+  }, [queue]);
+
+  const filteredQueue = useMemo(() => {
+    if (!queue || !tagFilter) return queue;
+    return queue.filter((item) => String(item.studyLog.tag?.id) === tagFilter);
+  }, [queue, tagFilter]);
+
+  const currentItem = filteredQueue?.[0] ?? null;
  const currentDetail = currentItem ? detailCache[currentItem.studyLogId] ?? null : null;
  const currentProblem = currentDetail?.problem ?? null;
  const currentPassage = currentProblem?.passage ?? null;
@@ -513,6 +529,35 @@ export default function ReviewPage() {
              </CompletionStat>
            </CompletionStats>

+            {(() => {
+              const tagStats = new Map<string, { name: string; hard: number; medium: number; easy: number }>();
+              for (const entry of history) {
+                if (entry.action === 'skip') continue;
+                const tagName = entry.item.studyLog.tag?.name ?? '미분류';
+                const prev = tagStats.get(tagName) ?? { name: tagName, hard: 0, medium: 0, easy: 0 };
+                prev[entry.action as 'hard' | 'medium' | 'easy'] += 1;
+                tagStats.set(tagName, prev);
+              }
+              if (tagStats.size === 0) return null;
+              return (
+                <TagStatsWrap>
+                  <TagStatsTitle>태그별 결과</TagStatsTitle>
+                  <TagStatsList>
+                    {Array.from(tagStats.values()).map((tag) => (
+                      <TagStatRow key={tag.name}>
+                        <TagStatName>{tag.name}</TagStatName>
+                        <TagStatBadges>
+                          {tag.hard > 0 && <TagStatBadge $tone="hard">{tag.hard}</TagStatBadge>}
+                          {tag.medium > 0 && <TagStatBadge $tone="medium">{tag.medium}</TagStatBadge>}
+                          {tag.easy > 0 && <TagStatBadge $tone="easy">{tag.easy}</TagStatBadge>}
+                        </TagStatBadges>
+                      </TagStatRow>
+                    ))}
+                  </TagStatsList>
+                </TagStatsWrap>
+              );
+            })()}
+
            <CompletionActions>
              <Link href="/dashboard">
                <Button as="span" $variant="white">
@@ -577,6 +622,28 @@ export default function ReviewPage() {
              </HintChip>
            ))}
          </HintStrip>
+
+          {availableTags.length > 1 && (
+            <TagFilterStrip>
+              <TagFilterChip
+                type="button"
+                $active={tagFilter === null}
+                onClick={() => setTagFilter(null)}
+              >
+                전체 ({queue?.length ?? 0})
+              </TagFilterChip>
+              {availableTags.map((tag) => (
+                <TagFilterChip
+                  key={tag.id}
+                  type="button"
+                  $active={tagFilter === tag.id}
+                  onClick={() => setTagFilter(tagFilter === tag.id ? null : tag.id)}
+                >
+                  {tag.name} ({queue?.filter((i) => String(i.studyLog.tag?.id) === tag.id).length ?? 0})
+                </TagFilterChip>
+              ))}
+            </TagFilterStrip>
+          )}
        </TopPanel>

        <StackStage>
@@ -1809,6 +1876,83 @@ const PromptImageWrap = styled.div`
  background: #fff;
 `;

+const TagFilterStrip = styled.div`
+  display: flex;
+  gap: 6px;
+  flex-wrap: wrap;
+  margin-top: 8px;
+`;
+
+const TagFilterChip = styled.button<{ $active: boolean }>`
+  padding: 5px 12px;
+  border-radius: 99px;
+  border: 1px solid ${({ $active }) => ($active ? 'rgba(129,140,248,0.5)' : theme.color.borderSoftAlpha)};
+  background: ${({ $active }) => ($active ? 'rgba(79,70,229,0.15)' : 'rgba(255,255,255,0.03)')};
+  color: ${({ $active }) => ($active ? '#c7d2fe' : theme.color.textSub)};
+  font-size: 12px;
+  font-weight: 600;
+  cursor: pointer;
+  transition: all 0.15s;
+  &:hover { background: rgba(79,70,229,0.1); color: ${theme.color.textBright}; }
+`;
+
+const TagStatsWrap = styled.div`
+  margin-top: 16px;
+  padding: 14px;
+  border-radius: 14px;
+  background: rgba(255,255,255,0.03);
+  border: 1px solid ${theme.color.borderSoftAlpha};
+`;
+
+const TagStatsTitle = styled.div`
+  font-size: 12px;
+  font-weight: 700;
+  color: ${theme.color.textSub};
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+  margin-bottom: 10px;
+`;
+
+const TagStatsList = styled.div`
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+`;
+
+const TagStatRow = styled.div`
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+`;
+
+const TagStatName = styled.span`
+  font-size: 13px;
+  font-weight: 600;
+  color: ${theme.color.textBright};
+`;
+
+const TagStatBadges = styled.div`
+  display: flex;
+  gap: 4px;
+`;
+
+const TagStatBadge = styled.span<{ $tone: 'hard' | 'medium' | 'easy' }>`
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  min-width: 22px;
+  height: 22px;
+  padding: 0 6px;
+  border-radius: 6px;
+  font-size: 11px;
+  font-weight: 700;
+  background: ${({ $tone }) =>
+    $tone === 'hard' ? 'rgba(239,68,68,0.15)' : $tone === 'medium' ? 'rgba(245,158,11,0.15)' : 'rgba(34,197,94,0.15)'};
+  color: ${({ $tone }) =>
+    $tone === 'hard' ? '#f87171' : $tone === 'medium' ? '#fbbf24' : '#4ade80'};
+`;
+
 const AnswerRevealBlock = styled.div`
  display: flex;
  align-items: center;