add habit leveling/XP system, explicit fail marking for missed habits, and scrollable habit tabs

- Habits and the account now accumulate XP and levels from check streaks, with
  streak/level-up celebration banners and push notifications.
- The "yesterday missed" banner on /today now lets a habit be explicitly marked
  failed (not just checked done), backed by a new HabitLog.status column so
  completion-rate/streak calculations never count a failed day as done.
- The habit management tabs scroll horizontally on narrow screens instead of
  wrapping to two lines, with a pure-CSS edge shadow indicating more content.

app/models/habit.py

@@ -10,6 +10,16 @@ from app.database import Base
 ALL_WEEKDAYS_MASK = 0b1111111  # 월~일 전부 (bit0=월 ... bit6=일)
 
 
+def _by_value(enum_cls: type[enum.Enum]) -> list[str]:
+    """SQLAlchemy Enum이 DB에 멤버 이름(예: "MEDIUM")이 아니라 값(예: "medium")을 쓰도록 강제한다.
+
+    values_callable을 안 주면 SQLAlchemy는 기본적으로 .name을 저장하는데, 이 앱의 CHECK 제약조건과
+    마이그레이션 기본값(server_default)은 전부 소문자 .value를 기준으로 작성되어 있어 불일치가 생긴다
+    (실제로 difficulty 컬럼에서 이 불일치로 LookupError가 발생한 사례가 있었음).
+    """
+    return [member.value for member in enum_cls]
+
+
 class HabitType(str, enum.Enum):
     BUILD = "build"  # 만들고 싶은 습관
     QUIT = "quit"  # 멈추고 싶은 습관
@@ -52,13 +62,19 @@ class Habit(Base):
         ForeignKey("user.id", ondelete="CASCADE"), nullable=True
     )
     name: Mapped[str] = mapped_column(String(200), nullable=False)
-    habit_type: Mapped[HabitType] = mapped_column(Enum(HabitType, native_enum=False, length=20), nullable=False)
+    habit_type: Mapped[HabitType] = mapped_column(
+        Enum(HabitType, native_enum=False, length=20, values_callable=_by_value), nullable=False
+    )
     status: Mapped[HabitStatus] = mapped_column(
-        Enum(HabitStatus, native_enum=False, length=20), nullable=False, default=HabitStatus.ACTIVE
+        Enum(HabitStatus, native_enum=False, length=20, values_callable=_by_value),
+        nullable=False,
+        default=HabitStatus.ACTIVE,
     )
     weekdays_mask: Mapped[int] = mapped_column(SmallInteger, nullable=False, default=ALL_WEEKDAYS_MASK)
     difficulty: Mapped[HabitDifficulty] = mapped_column(
-        Enum(HabitDifficulty, native_enum=False, length=20), nullable=False, default=HabitDifficulty.MEDIUM
+        Enum(HabitDifficulty, native_enum=False, length=20, values_callable=_by_value),
+        nullable=False,
+        default=HabitDifficulty.MEDIUM,
     )
     condition_text: Mapped[str | None] = mapped_column(String(300), nullable=True)
     reminder_time: Mapped[time | None] = mapped_column(Time, nullable=True)

app/models/habit_log.py

@@ -1,10 +1,17 @@
+import enum
 from datetime import date, datetime
 
-from sqlalchemy import Date, ForeignKey, Integer, UniqueConstraint
+from sqlalchemy import Date, Enum, ForeignKey, Integer, UniqueConstraint
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 from sqlalchemy.sql import func
 
 from app.database import Base
+from app.models.habit import _by_value
+
+
+class HabitLogStatus(str, enum.Enum):
+    DONE = "done"
+    FAILED = "failed"  # /today의 "어제 놓친 습관" 배너에서 사용자가 명시적으로 실패를 확정한 경우
 
 
 class HabitLog(Base):
@@ -14,6 +21,11 @@ class HabitLog(Base):
     id: Mapped[int] = mapped_column(Integer, primary_key=True)
     habit_id: Mapped[int] = mapped_column(ForeignKey("habit.id", ondelete="CASCADE"), nullable=False)
     log_date: Mapped[date] = mapped_column(Date, nullable=False)
+    status: Mapped[HabitLogStatus] = mapped_column(
+        Enum(HabitLogStatus, native_enum=False, length=20, values_callable=_by_value),
+        nullable=False,
+        default=HabitLogStatus.DONE,
+    )
     checked_at: Mapped[datetime] = mapped_column(server_default=func.now(), nullable=False)
 
     habit: Mapped["Habit"] = relationship(back_populates="logs")

app/routers/logs.py

@@ -23,8 +23,8 @@ def toggle_log(habit_id: int, db: Session = Depends(get_db), current_user: User
     habit = habit_service.get_habit(db, habit_id, current_user.id)
     if habit is None:
         raise HTTPException(status_code=404, detail="습관을 찾을 수 없습니다")
-    checked, milestone_streak = log_service.toggle_check_and_celebrate(db, habit, date.today())
-    return {"checked": checked, "milestone_streak": milestone_streak}
+    checked, milestone_streak, level_up = log_service.toggle_check_and_celebrate(db, habit, date.today())
+    return {"checked": checked, "milestone_streak": milestone_streak, "level_up": level_up}
 
 
 @router.get("/logs", response_model=list[HabitLogOut])

app/routers/pages.py

@@ -14,7 +14,14 @@ from app.models.user import User
 from app.schemas.habit import HabitCreate, HabitUpdate
 from app.security import get_current_user_optional
 from app.services import habit_service, log_service
-from app.template_utils import difficulty_label, goal_progress, heatmap_opacity, is_milestone_streak, weekday_label
+from app.template_utils import (
+    difficulty_label,
+    goal_progress,
+    heatmap_opacity,
+    is_milestone_streak,
+    level_tier_emoji,
+    weekday_label,
+)
 
 router = APIRouter()
 
@@ -24,6 +31,7 @@ templates.env.globals["heatmap_opacity"] = heatmap_opacity
 templates.env.globals["is_milestone_streak"] = is_milestone_streak
 templates.env.globals["difficulty_label"] = difficulty_label
 templates.env.globals["goal_progress"] = goal_progress
+templates.env.globals["level_tier_emoji"] = level_tier_emoji
 templates.env.globals["habit_difficulties"] = list(HabitDifficulty)
 
 
@@ -57,6 +65,7 @@ def _today_context(db: Session, user_id: int, **extra) -> dict:
         "yesterday_missed": log_service.get_yesterday_missed_items(db, user_id),
         "total_count": len(all_items),
         "checked_count": sum(1 for item in all_items if item.checked),
+        "account_level": log_service.get_account_level(db, user_id),
         **extra,
     }
 
@@ -84,8 +93,12 @@ def toggle_today_page(request: Request, habit_id: int, db: Session = Depends(get
     if habit is None:
         return Response(status_code=404)
 
-    _, milestone_streak = log_service.toggle_check_and_celebrate(db, habit, date.today())
-    extra = {"celebrate_habit_name": habit.name, "celebrate_streak": milestone_streak} if milestone_streak else {}
+    _, milestone_streak, level_up = log_service.toggle_check_and_celebrate(db, habit, date.today())
+    extra = {"celebrate_habit_name": habit.name} if (milestone_streak or level_up) else {}
+    if milestone_streak:
+        extra["celebrate_streak"] = milestone_streak
+    if level_up:
+        extra["celebrate_level_up"] = level_up
     return templates.TemplateResponse(
         request,
         "partials/today_content.html",
@@ -104,8 +117,12 @@ def toggle_yesterday_page(request: Request, habit_id: int, db: Session = Depends
         return Response(status_code=404)
 
     yesterday = date.today() - timedelta(days=1)
-    _, milestone_streak = log_service.toggle_check_and_celebrate(db, habit, yesterday)
-    extra = {"celebrate_habit_name": habit.name, "celebrate_streak": milestone_streak} if milestone_streak else {}
+    _, milestone_streak, level_up = log_service.toggle_check_and_celebrate(db, habit, yesterday)
+    extra = {"celebrate_habit_name": habit.name} if (milestone_streak or level_up) else {}
+    if milestone_streak:
+        extra["celebrate_streak"] = milestone_streak
+    if level_up:
+        extra["celebrate_level_up"] = level_up
     return templates.TemplateResponse(
         request,
         "partials/today_content.html",
@@ -113,6 +130,25 @@ def toggle_yesterday_page(request: Request, habit_id: int, db: Session = Depends
     )
 
 
+@router.post("/today/{habit_id}/fail-yesterday")
+def fail_yesterday_page(request: Request, habit_id: int, db: Session = Depends(get_db)):
+    current = _current_user_or_redirect(request, db)
+    if isinstance(current, RedirectResponse):
+        return current
+
+    habit = habit_service.get_habit(db, habit_id, current.id)
+    if habit is None:
+        return Response(status_code=404)
+
+    yesterday = date.today() - timedelta(days=1)
+    log_service.mark_failed(db, habit.id, yesterday)
+    return templates.TemplateResponse(
+        request,
+        "partials/today_content.html",
+        {"logged_in": True, "current_user": current, **_today_context(db, current.id)},
+    )
+
+
 @router.get("/habits")
 def habits_page(request: Request, tab: str = "build", db: Session = Depends(get_db)):
     current = _current_user_or_redirect(request, db)
@@ -140,6 +176,7 @@ def habits_page(request: Request, tab: str = "build", db: Session = Depends(get_
             "habits": habits,
             "habit_type": tab,
             "stats_map": stats_map,
+            "account_level": log_service.get_account_level(db, current.id),
         },
     )
 
@@ -355,5 +392,12 @@ def history_page(
         context = _month_context(db, current.id, year or today.year, month or today.month)
 
     return templates.TemplateResponse(
-        request, "history.html", {"logged_in": True, "current_user": current, **context}
+        request,
+        "history.html",
+        {
+            "logged_in": True,
+            "current_user": current,
+            "account_level": log_service.get_account_level(db, current.id),
+            **context,
+        },
     )

app/schemas/habit_log.py

@@ -2,6 +2,8 @@ from datetime import date, datetime
 
 from pydantic import BaseModel, ConfigDict
 
+from app.schemas.level import LevelInfo
+
 
 class HabitLogOut(BaseModel):
     model_config = ConfigDict(from_attributes=True)
@@ -22,6 +24,7 @@ class TodayItem(BaseModel):
     completion_rate: float
     current_streak: int
     scheduled_days: int
+    level_info: LevelInfo
 
 
 class MonthlySummaryDay(BaseModel):
@@ -43,3 +46,4 @@ class HabitStats(BaseModel):
     current_streak: int  # 오늘(또는 어제)부터 거슬러 올라가며 끊기지 않고 체크한 예정일 수
     scheduled_days: int
     checked_days: int
+    level_info: LevelInfo

app/schemas/level.py

@@ -0,0 +1,9 @@
+from pydantic import BaseModel
+
+
+class LevelInfo(BaseModel):
+    xp: int  # 누적 경험치 (0 이상)
+    level: int  # 현재 레벨 (1부터 시작)
+    xp_into_level: int  # 현재 레벨 진입 후 쌓인 xp
+    xp_for_next_level: int  # 다음 레벨까지 필요한 xp
+    progress_pct: float  # 다음 레벨까지 진행률 (0~100)

app/services/level_service.py

@@ -0,0 +1,48 @@
+from app.schemas.level import LevelInfo
+
+# 체크 1회당 얻는 기본 경험치.
+XP_PER_CHECK = 10
+
+# 예정일을 놓쳤을 때의 페널티. 연속으로 놓칠수록 (miss_streak * MISS_PENALTY_BASE)로 가속되며,
+# MISS_PENALTY_CAP에서 더 이상 커지지 않는다(끝없이 방치된 습관이 비정상적인 값으로 폭주하지 않도록).
+MISS_PENALTY_BASE = 8
+MISS_PENALTY_CAP = 80
+
+# 연속 달성일 마일스톤(log_service.MILESTONE_STREAKS와 동일한 값) 도달 시 추가로 얹어주는 보너스 경험치.
+STREAK_MILESTONE_BONUS_XP: dict[int, int] = {
+    7: 20,
+    30: 80,
+    66: 150,
+    100: 250,
+    200: 500,
+    365: 1000,
+}
+
+# 레벨업에 필요한 경험치는 LEVEL_BASE_XP에서 시작해 레벨마다 LEVEL_STEP_XP씩 늘어난다
+# (초반엔 빠르게, 갈수록 완만하게 오르는 곡선).
+LEVEL_BASE_XP = 20
+LEVEL_STEP_XP = 10
+
+
+def _xp_required_for_level(level: int) -> int:
+    """`level`에서 `level + 1`로 올라가는 데 필요한 경험치."""
+    return LEVEL_BASE_XP + LEVEL_STEP_XP * (level - 1)
+
+
+def level_from_xp(xp: int) -> LevelInfo:
+    xp = max(xp, 0)
+    level = 1
+    remaining = xp
+    while True:
+        needed = _xp_required_for_level(level)
+        if remaining < needed:
+            progress_pct = round(remaining / needed * 100, 1)
+            return LevelInfo(
+                xp=xp,
+                level=level,
+                xp_into_level=remaining,
+                xp_for_next_level=needed,
+                progress_pct=progress_pct,
+            )
+        remaining -= needed
+        level += 1

app/services/log_service.py

@@ -5,9 +5,10 @@ from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
 from app.models.habit import Habit, HabitStatus, HabitType
-from app.models.habit_log import HabitLog
+from app.models.habit_log import HabitLog, HabitLogStatus
 from app.schemas.habit_log import HabitStats, MonthlySummaryDay, TodayItem, WeeklyMatrixRow
-from app.services import habit_service, push_service
+from app.schemas.level import LevelInfo
+from app.services import habit_service, level_service, push_service
 
 # 체크 시 축하 푸시/배지를 트리거하는 연속 달성일 마일스톤.
 MILESTONE_STREAKS = {7, 30, 66, 100, 200, 365}
@@ -25,6 +26,7 @@ def _to_today_item(db: Session, habit: Habit, checked: bool) -> TodayItem:
         completion_rate=stats.completion_rate,
         current_streak=stats.current_streak,
         scheduled_days=stats.scheduled_days,
+        level_info=stats.level_info,
     )
 
 
@@ -40,7 +42,9 @@ def get_today_items(db: Session, user_id: int, target_date: date) -> tuple[list[
         checked_ids = set(
             db.scalars(
                 select(HabitLog.habit_id).where(
-                    HabitLog.log_date == target_date, HabitLog.habit_id.in_(habit_ids)
+                    HabitLog.log_date == target_date,
+                    HabitLog.habit_id.in_(habit_ids),
+                    HabitLog.status == HabitLogStatus.DONE,
                 )
             )
         )
@@ -51,10 +55,28 @@ def get_today_items(db: Session, user_id: int, target_date: date) -> tuple[list[
 
 
 def get_yesterday_missed_items(db: Session, user_id: int) -> list[TodayItem]:
-    """어제 예정되어 있었지만 아직 체크하지 않은 습관 목록 (형성+중단 합쳐서, /today 화면의 소급 체크용)."""
+    """어제 예정되어 있었지만 아직 완료/실패가 결정되지 않은 습관 목록
+
+    (형성+중단 합쳐서, /today 화면의 소급 체크·실패 확정용). 완료로 체크했거나 실패로 확정한
+    습관은 둘 다 "결정됨"으로 보고 목록에서 뺀다.
+    """
     yesterday = date.today() - timedelta(days=1)
     build_items, quit_items = get_today_items(db, user_id, yesterday)
-    return [item for item in build_items + quit_items if not item.checked]
+    all_items = build_items + quit_items
+
+    habit_ids = [item.habit_id for item in all_items]
+    failed_ids: set[int] = set()
+    if habit_ids:
+        failed_ids = set(
+            db.scalars(
+                select(HabitLog.habit_id).where(
+                    HabitLog.log_date == yesterday,
+                    HabitLog.habit_id.in_(habit_ids),
+                    HabitLog.status == HabitLogStatus.FAILED,
+                )
+            )
+        )
+    return [item for item in all_items if not item.checked and item.habit_id not in failed_ids]
 
 
 def toggle_check(db: Session, habit_id: int, log_date: date) -> bool:
@@ -72,25 +94,43 @@ def toggle_check(db: Session, habit_id: int, log_date: date) -> bool:
     return True
 
 
-def toggle_check_and_celebrate(db: Session, habit: Habit, log_date: date) -> tuple[bool, int | None]:
-    """체크를 토글하고, 새로 체크되어 스트릭이 마일스톤에 도달했으면 축하 푸시를 보낸다.
+def mark_failed(db: Session, habit_id: int, log_date: date) -> None:
+    """해당 날짜를 명시적으로 실패로 확정한다. 이미 완료/실패가 결정된 날짜면 아무 것도 하지 않는다."""
+    existing = db.scalar(select(HabitLog).where(HabitLog.habit_id == habit_id, HabitLog.log_date == log_date))
+    if existing:
+        return
+    db.add(HabitLog(habit_id=habit_id, log_date=log_date, status=HabitLogStatus.FAILED))
+    db.commit()
 
-    반환값: (checked, milestone_streak). milestone_streak은 이번 토글로 막 달성한 마일스톤 값이면 그 값,
-    체크 해제거나 마일스톤이 아니면 None.
+
+def toggle_check_and_celebrate(db: Session, habit: Habit, log_date: date) -> tuple[bool, int | None, int | None]:
+    """체크를 토글하고, 새로 체크되어 스트릭 마일스톤이나 레벨업에 도달했으면 축하 푸시를 보낸다.
+
+    반환값: (checked, milestone_streak, level_up).
+    - milestone_streak: 이번 토글로 막 달성한 연속 달성일 마일스톤 값, 아니면 None.
+    - level_up: 이번 토글로 막 오른 새 레벨, 아니면 None.
+    체크 해제인 경우 둘 다 None.
     """
+    level_before = get_habit_stats(db, habit).level_info.level
     checked = toggle_check(db, habit.id, log_date)
     if not checked:
-        return checked, None
+        return checked, None, None
 
-    streak = get_habit_stats(db, habit).current_streak
-    if streak not in MILESTONE_STREAKS:
-        return checked, None
+    stats = get_habit_stats(db, habit)
+    streak = stats.current_streak
+    milestone_streak = streak if streak in MILESTONE_STREAKS else None
+    level_up = stats.level_info.level if stats.level_info.level > level_before else None
 
     if habit.user_id is not None:
+        if milestone_streak is not None:
             push_service.send_to_user(
                 db, habit.user_id, title=f"🔥 {habit.name}", body=f"{streak}일 연속 달성했어요!", url="/today"
             )
-    return checked, streak
+        if level_up is not None:
+            push_service.send_to_user(
+                db, habit.user_id, title=f"⭐ {habit.name}", body=f"레벨 {level_up}로 올랐어요!", url="/today"
+            )
+    return checked, milestone_streak, level_up
 
 
 def list_logs(
@@ -112,7 +152,11 @@ def _checked_counts_by_date(db: Session, habit_ids: list[int], start: date, end:
         return {}
     rows = db.execute(
         select(HabitLog.log_date, func.count(HabitLog.id))
-        .where(HabitLog.habit_id.in_(habit_ids), HabitLog.log_date.between(start, end))
+        .where(
+            HabitLog.habit_id.in_(habit_ids),
+            HabitLog.log_date.between(start, end),
+            HabitLog.status == HabitLogStatus.DONE,
+        )
         .group_by(HabitLog.log_date)
     ).all()
     return {row[0]: row[1] for row in rows}
@@ -175,6 +219,7 @@ def get_period_completion_rate(db: Session, user_id: int, start: date, end: date
 
 def get_habit_stats(db: Session, habit: Habit) -> HabitStats:
     """습관 생성일부터 오늘까지의 완료율과, 오늘(또는 어제)부터 거슬러 올라간 연속 달성일을 계산한다.
+    같은 순회에서 레벨/경험치(XP)도 함께 누적한다.
 
     요일 스케줄은 현재 습관의 weekdays_mask를 과거에도 그대로 적용한 것으로 간주한다
     (과거 요일 변경 이력은 추적하지 않음 — 월별/주별 집계와 같은 단순화).
@@ -182,16 +227,45 @@ def get_habit_stats(db: Session, habit: Habit) -> HabitStats:
     today = date.today()
     start = habit.created_at.date()
 
-    checked_dates = set(db.scalars(select(HabitLog.log_date).where(HabitLog.habit_id == habit.id)))
+    # 완료/포기된 습관은 그 시점 이후로 XP가 더 이상 변하지 않는다(동결) — completion_rate/current_streak
+    # 계산 범위는 건드리지 않고 XP 누적에만 이 경계를 적용한다.
+    freeze_date: date | None = None
+    if habit.status != HabitStatus.ACTIVE and (habit.completed_at or habit.abandoned_at):
+        freeze_date = (habit.completed_at or habit.abandoned_at).date()
+
+    checked_dates = set(
+        db.scalars(
+            select(HabitLog.log_date).where(
+                HabitLog.habit_id == habit.id, HabitLog.status == HabitLogStatus.DONE
+            )
+        )
+    )
 
     scheduled_days = 0
     checked_days = 0
+    xp = 0
+    hit_streak = 0
+    miss_streak = 0
     d = start
     while d <= today:
         if habit.is_scheduled_on(d.weekday()):
             scheduled_days += 1
-            if d in checked_dates:
+            is_checked = d in checked_dates
+            if is_checked:
                 checked_days += 1
+            if freeze_date is None or d <= freeze_date:
+                if d == today and not is_checked:
+                    pass  # 오늘은 아직 안 지났으니 XP 변동 없음 (current_streak과 같은 규칙)
+                elif is_checked:
+                    hit_streak += 1
+                    miss_streak = 0
+                    xp += level_service.XP_PER_CHECK
+                    xp += level_service.STREAK_MILESTONE_BONUS_XP.get(hit_streak, 0)
+                else:
+                    hit_streak = 0
+                    miss_streak += 1
+                    penalty = min(level_service.MISS_PENALTY_BASE * miss_streak, level_service.MISS_PENALTY_CAP)
+                    xp = max(0, xp - penalty)
         d += timedelta(days=1)
 
     completion_rate = round(checked_days / scheduled_days * 100, 1) if scheduled_days else 0.0
@@ -212,6 +286,7 @@ def get_habit_stats(db: Session, habit: Habit) -> HabitStats:
         current_streak=streak,
         scheduled_days=scheduled_days,
         checked_days=checked_days,
+        level_info=level_service.level_from_xp(xp),
     )
 
 
@@ -226,7 +301,9 @@ def get_weekly_matrix(db: Session, user_id: int, week_start: date) -> list[Weekl
     if habit_ids:
         rows = db.execute(
             select(HabitLog.habit_id, HabitLog.log_date).where(
-                HabitLog.habit_id.in_(habit_ids), HabitLog.log_date.between(week_days[0], week_days[-1])
+                HabitLog.habit_id.in_(habit_ids),
+                HabitLog.log_date.between(week_days[0], week_days[-1]),
+                HabitLog.status == HabitLogStatus.DONE,
             )
         ).all()
         checked_pairs = {(r[0], r[1]) for r in rows}
@@ -259,3 +336,14 @@ def get_weekly_matrix(db: Session, user_id: int, week_start: date) -> list[Weekl
             )
         )
     return result
+
+
+def get_account_level(db: Session, user_id: int) -> LevelInfo:
+    """유저가 가진 모든 습관(활성+완료+포기)의 XP를 합산해 계정 전체 레벨을 계산한다.
+
+    완료/포기된 습관도 (동결된 상태로) 합산에 포함한다 — 완료해도 그동안 쌓은 계정 레벨은 유지되어야 한다.
+    습관별 레벨과 같은 곡선(level_service.level_from_xp)을 그대로 재사용한다.
+    """
+    habits = habit_service.list_habits(db, user_id)
+    total_xp = sum(get_habit_stats(db, h).level_info.xp for h in habits)
+    return level_service.level_from_xp(total_xp)

app/static/css/style.css

@@ -344,13 +344,30 @@ label {
   min-height: 1em;
 }
 
-/* 탭 */
+/* 탭 — 좁은 화면에서 4개가 다 안 들어가면 줄바꿈 대신 가로 스크롤.
+   양 끝에 스크롤 가능 방향으로만 그림자가 지도록 하는 순수 CSS 트릭:
+   앞쪽 두 레이어(배경색→투명 그라데이션, background-attachment: local)는 콘텐츠와 같이 스크롤되면서
+   탭 텍스트를 가려 페이드아웃시키고, 뒤쪽 두 레이어(radial-gradient 그림자, attachment: scroll)는
+   스크롤 컨테이너 기준으로 고정되어 있다 — 콘텐츠 레이어가 그 위를 덮을 수 있을 때만(=그 방향으로
+   더 스크롤할 내용이 있을 때만) 그림자가 드러나 보인다. 끝까지 스크롤하면 콘텐츠 레이어가 그림자를
+   완전히 덮어 자연스럽게 사라진다. */
 .tabs {
   display: flex;
-  flex-wrap: wrap;
+  flex-wrap: nowrap;
+  overflow-x: auto;
+  -webkit-overflow-scrolling: touch;
   gap: 6px;
   margin-bottom: var(--space-2);
   border-bottom: 1px solid var(--color-border);
+  background:
+    linear-gradient(to right, var(--color-bg) 50%, transparent) left,
+    linear-gradient(to left, var(--color-bg) 50%, transparent) right,
+    radial-gradient(farthest-side at 0 50%, rgba(0, 0, 0, 0.2), transparent) left,
+    radial-gradient(farthest-side at 100% 50%, rgba(0, 0, 0, 0.2), transparent) right;
+  background-repeat: no-repeat;
+  background-color: var(--color-bg);
+  background-size: 20px 100%, 20px 100%, 10px 100%, 10px 100%;
+  background-attachment: local, local, scroll, scroll;
 }
 
 .tabs a {
@@ -360,6 +377,9 @@ label {
   padding: 10px 4px;
   margin-right: var(--space-2);
   border-bottom: 2px solid transparent;
+  white-space: nowrap;
+  flex-shrink: 0;
+  touch-action: manipulation;
 }
 
 .tabs a.active {
@@ -603,6 +623,72 @@ label {
   }
 }
 
+/* 레벨 배지 & XP 진행바 */
+.level-badge {
+  background: var(--color-gold-tint);
+  color: var(--color-gold);
+  border-color: var(--color-gold);
+  font-weight: 600;
+}
+
+.xp-bar-wrap {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+  margin-top: 4px;
+}
+
+.xp-bar {
+  flex: 1 1 auto;
+  height: 5px;
+  border-radius: 999px;
+  background: var(--color-bg);
+  border: 1px solid var(--color-border);
+  overflow: hidden;
+}
+
+.xp-bar-fill {
+  height: 100%;
+  border-radius: 999px;
+  background: var(--color-accent);
+}
+
+.xp-bar-label {
+  flex-shrink: 0;
+  font-size: 11px;
+  color: var(--color-text-muted);
+}
+
+.account-level-card {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: var(--space-2);
+}
+
+.account-level-card .level-badge {
+  font-size: 13px;
+  padding: 4px 12px;
+}
+
+.account-level-card .xp-bar-wrap {
+  flex: 1 1 auto;
+  max-width: 220px;
+  margin-top: 0;
+}
+
+.nav-level-pill {
+  display: inline-block;
+  font-size: 11px;
+  font-weight: 600;
+  padding: 1px 7px;
+  border-radius: 999px;
+  background: var(--color-gold-tint);
+  color: var(--color-gold);
+  border: 1px solid var(--color-gold);
+  flex-shrink: 0;
+}
+
 /* 월별 캘린더 */
 .calendar-grid {
   display: grid;

app/template_utils.py

@@ -17,6 +17,16 @@ def is_milestone_streak(streak: int) -> bool:
     return streak in MILESTONE_STREAKS
 
 
+def level_tier_emoji(level: int) -> str:
+    if level >= 20:
+        return "💎"
+    if level >= 10:
+        return "⭐"
+    if level >= 5:
+        return "🔥"
+    return "🌱"
+
+
 def weekday_label(mask: int) -> str:
     if mask == ALL_WEEKDAYS_MASK:
         return "매일"

app/templates/partials/habit_item.html

@@ -35,6 +35,11 @@
             {{ '🏆' if is_milestone_streak(stats.current_streak) else '🔥' }} 연속 {{ stats.current_streak }}일
           </span>
           {% endif %}
+          <span class="badge level-badge">{{ level_tier_emoji(stats.level_info.level) }} Lv.{{ stats.level_info.level }}</span>
+        </div>
+        <div class="xp-bar-wrap">
+          <div class="xp-bar"><div class="xp-bar-fill" style="width: {{ stats.level_info.progress_pct }}%;"></div></div>
+          <span class="xp-bar-label">{{ stats.level_info.xp_into_level }}/{{ stats.level_info.xp_for_next_level }} xp</span>
         </div>
         {% endif %}
       </div>

app/templates/partials/today_content.html

@@ -3,6 +3,19 @@
   🎉 <strong>{{ celebrate_habit_name }}</strong> {{ celebrate_streak }}일 연속 달성! 축하해요!
 </div>
 {% endif %}
+{% if celebrate_level_up %}
+<div class="celebration-banner" x-data="{ show: true }" x-init="setTimeout(() => show = false, 4000)" x-show="show" x-transition>
+  ⭐ <strong>{{ celebrate_habit_name }}</strong> 레벨 {{ celebrate_level_up }}로 올랐어요!
+</div>
+{% endif %}
+
+<div class="card account-level-card">
+  <span class="badge level-badge">{{ level_tier_emoji(account_level.level) }} 계정 Lv.{{ account_level.level }}</span>
+  <div class="xp-bar-wrap">
+    <div class="xp-bar"><div class="xp-bar-fill" style="width: {{ account_level.progress_pct }}%;"></div></div>
+    <span class="xp-bar-label">{{ account_level.xp_into_level }}/{{ account_level.xp_for_next_level }} xp</span>
+  </div>
+</div>
 
 <div
   class="card"

app/templates/partials/today_item.html

@@ -20,6 +20,11 @@
           {{ '🏆' if is_milestone_streak(item.current_streak) else '🔥' }} 연속 {{ item.current_streak }}일
         </span>
         {% endif %}
+        <span class="badge level-badge">{{ level_tier_emoji(item.level_info.level) }} Lv.{{ item.level_info.level }}</span>
+      </div>
+      <div class="xp-bar-wrap">
+        <div class="xp-bar"><div class="xp-bar-fill" style="width: {{ item.level_info.progress_pct }}%;"></div></div>
+        <span class="xp-bar-label">{{ item.level_info.xp_into_level }}/{{ item.level_info.xp_for_next_level }} xp</span>
       </div>
       {% endif %}
     </div>

app/templates/partials/yesterday_item.html

@@ -13,4 +13,14 @@
       {% if item.condition_text %}<div class="habit-item-condition">{{ item.condition_text }}</div>{% endif %}
     </div>
   </div>
+  <div class="habit-item-actions">
+    <button
+      type="button"
+      class="btn btn-danger-ghost"
+      hx-post="/today/{{ item.habit_id }}/fail-yesterday"
+      hx-target="#today-content"
+      hx-swap="innerHTML"
+      aria-label="{{ item.name }} 어제 실패로 표시"
+    >실패로 표시</button>
+  </div>
 </div>

migrations/versions/0008_normalize_habit_enum_casing.py

@@ -0,0 +1,32 @@
+"""normalize habit_type/status/difficulty column casing to lowercase
+
+Revision ID: 0008_normalize_habit_enum_casing
+Revises: 0007_add_habit_difficulty
+Create Date: 2026-07-19
+
+SQLAlchemy의 Enum 타입은 values_callable을 안 주면 기본적으로 enum 멤버의 .name(대문자, 예:
+"MEDIUM")을 DB에 저장하는데, 이 앱의 CHECK 제약조건과 difficulty 컬럼의 server_default는 전부
+소문자 .value(예: "medium")를 기준으로 작성되어 있었다. habit_type/status는 지금까지 ORM으로
+삽입된 대문자 값만 있어서 우연히 안 터졌고, difficulty는 마이그레이션이 직접 SQL로 넣은 소문자
+기본값과 섞여 LookupError가 발생했다. 모델 쪽은 values_callable을 추가해 앞으로는 항상 소문자로
+쓰도록 고쳤고, 이 마이그레이션은 기존에 대문자로 저장된 행을 소문자로 정규화한다.
+"""
+from typing import Sequence, Union
+
+from alembic import op
+
+revision: str = "0008_normalize_habit_enum_casing"
+down_revision: Union[str, None] = "0007_add_habit_difficulty"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.execute("UPDATE habit SET habit_type = LOWER(habit_type)")
+    op.execute("UPDATE habit SET status = LOWER(status)")
+    op.execute("UPDATE habit SET difficulty = LOWER(difficulty)")
+
+
+def downgrade() -> None:
+    # 대소문자 정규화는 되돌릴 필요가 없는 데이터 정리이므로 downgrade는 아무 것도 하지 않는다.
+    pass

migrations/versions/0009_add_habit_log_status.py

@@ -0,0 +1,32 @@
+"""add status (done/failed) to habit_log
+
+Revision ID: 0009_add_habit_log_status
+Revises: 0008_normalize_habit_enum_casing
+Create Date: 2026-07-20
+
+"어제 놓친 습관" 배너에서 사용자가 명시적으로 실패를 확정할 수 있게 하기 위해, "로그 행이 존재하면
+그 날 체크 완료"라는 기존 불변식을 유지하면서도 "완료"와 "실패"를 구분해야 한다. status 컬럼을
+추가하고 기존 행은 전부 완료였으므로 기본값 'done'으로 채운다.
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0009_add_habit_log_status"
+down_revision: Union[str, None] = "0008_normalize_habit_enum_casing"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "habit_log",
+        sa.Column("status", sa.String(length=20), nullable=False, server_default="done"),
+    )
+    op.create_check_constraint("ck_habit_log_status", "habit_log", "status in ('done','failed')")
+
+
+def downgrade() -> None:
+    op.drop_constraint("ck_habit_log_status", "habit_log", type_="check")
+    op.drop_column("habit_log", "status")

tests/test_level_service.py

@@ -0,0 +1,36 @@
+from app.services import level_service
+
+
+def test_level_from_xp_zero_is_level_one():
+    info = level_service.level_from_xp(0)
+    assert info.level == 1
+    assert info.xp_into_level == 0
+    assert info.xp_for_next_level == 20
+    assert info.progress_pct == 0.0
+
+
+def test_level_from_xp_just_below_threshold_stays_at_level():
+    info = level_service.level_from_xp(19)
+    assert info.level == 1
+    assert info.xp_into_level == 19
+    assert info.progress_pct == 95.0
+
+
+def test_level_from_xp_at_threshold_advances_level():
+    info = level_service.level_from_xp(20)
+    assert info.level == 2
+    assert info.xp_into_level == 0
+    assert info.xp_for_next_level == 30  # 레벨2->3 요구치는 레벨1->2보다 커진다(점점 완만해짐)
+
+
+def test_level_from_xp_requirement_grows_with_level():
+    # Lv1->2: 20xp, Lv2->3: 30xp, Lv3->4: 40xp (누적 90xp에서 Lv4 도달)
+    info = level_service.level_from_xp(90)
+    assert info.level == 4
+    assert info.xp_into_level == 0
+
+
+def test_level_from_xp_negative_floors_to_zero():
+    info = level_service.level_from_xp(-50)
+    assert info.level == 1
+    assert info.xp == 0

tests/test_log_service.py

@@ -1,8 +1,8 @@
 import calendar
 from datetime import date, datetime, timedelta
 
-from app.models.habit import ALL_WEEKDAYS_MASK, HabitType
-from app.models.habit_log import HabitLog
+from app.models.habit import ALL_WEEKDAYS_MASK, HabitStatus, HabitType
+from app.models.habit_log import HabitLog, HabitLogStatus
 from app.schemas.habit import HabitCreate
 from app.schemas.habit_log import MonthlySummaryDay
 from app.schemas.push import PushKeys, PushSubscribeRequest
@@ -30,6 +30,11 @@ def _check(db_session, habit_id, log_date):
     db_session.commit()
 
 
+def _fail(db_session, habit_id, log_date):
+    db_session.add(HabitLog(habit_id=habit_id, log_date=log_date, status=HabitLogStatus.FAILED))
+    db_session.commit()
+
+
 # ---- toggle_check ----
 
 
@@ -44,6 +49,30 @@ def test_toggle_check_sets_and_unsets(db_session, test_user):
     assert db_session.query(HabitLog).filter_by(habit_id=habit.id, log_date=today).count() == 0
 
 
+# ---- mark_failed ----
+
+
+def test_mark_failed_creates_failed_log(db_session, test_user):
+    habit = _make_habit(db_session, test_user.id)
+    yesterday = date.today() - timedelta(days=1)
+
+    log_service.mark_failed(db_session, habit.id, yesterday)
+
+    log = db_session.query(HabitLog).filter_by(habit_id=habit.id, log_date=yesterday).one()
+    assert log.status == HabitLogStatus.FAILED
+
+
+def test_mark_failed_does_not_overwrite_existing_log(db_session, test_user):
+    habit = _make_habit(db_session, test_user.id)
+    yesterday = date.today() - timedelta(days=1)
+    _check(db_session, habit.id, yesterday)  # 이미 완료로 체크된 상태
+
+    log_service.mark_failed(db_session, habit.id, yesterday)
+
+    log = db_session.query(HabitLog).filter_by(habit_id=habit.id, log_date=yesterday).one()
+    assert log.status == HabitLogStatus.DONE  # 실패로 덮어쓰지 않음
+
+
 # ---- toggle_check_and_celebrate ----
 
 
@@ -54,16 +83,18 @@ def test_toggle_check_and_celebrate_returns_milestone_on_streak_hit(db_session,
     for offset in range(6, 0, -1):  # 6일 전부터 어제까지 6일 연속 체크, 오늘 체크하면 7일째
         _check(db_session, habit.id, today - timedelta(days=offset))
 
-    checked, milestone = log_service.toggle_check_and_celebrate(db_session, habit, today)
+    checked, milestone, level_up = log_service.toggle_check_and_celebrate(db_session, habit, today)
     assert checked is True
     assert milestone == 7
+    assert level_up == 4  # 6일치(60xp, Lv3) -> 7일째 체크(70xp+마일스톤보너스20=90xp, Lv4)
 
 
 def test_toggle_check_and_celebrate_returns_none_when_not_milestone(db_session, test_user):
     habit = _make_habit(db_session, test_user.id)
-    checked, milestone = log_service.toggle_check_and_celebrate(db_session, habit, date.today())
+    checked, milestone, level_up = log_service.toggle_check_and_celebrate(db_session, habit, date.today())
     assert checked is True
     assert milestone is None
+    assert level_up is None
 
 
 def test_toggle_check_and_celebrate_returns_none_on_uncheck(db_session, test_user):
@@ -73,10 +104,11 @@ def test_toggle_check_and_celebrate_returns_none_on_uncheck(db_session, test_use
     for offset in range(6, -1, -1):  # 오늘까지 포함해 7일 연속 체크된 상태
         _check(db_session, habit.id, today - timedelta(days=offset))
 
-    # 이미 체크된 오늘을 다시 토글하면 해제되어야 하고, 마일스톤 여부와 무관하게 None이어야 한다.
-    checked, milestone = log_service.toggle_check_and_celebrate(db_session, habit, today)
+    # 이미 체크된 오늘을 다시 토글하면 해제되어야 하고, 마일스톤/레벨업 여부와 무관하게 None이어야 한다.
+    checked, milestone, level_up = log_service.toggle_check_and_celebrate(db_session, habit, today)
     assert checked is False
     assert milestone is None
+    assert level_up is None
 
 
 def test_toggle_check_and_celebrate_sends_push_on_milestone(db_session, test_user, monkeypatch):
@@ -95,7 +127,7 @@ def test_toggle_check_and_celebrate_sends_push_on_milestone(db_session, test_use
         _check(db_session, habit.id, today - timedelta(days=offset))
 
     log_service.toggle_check_and_celebrate(db_session, habit, today)
-    assert len(sent) == 1
+    assert len(sent) == 2  # 스트릭 마일스톤 푸시 1건 + 레벨업 푸시 1건
 
 
 # ---- get_today_items ----
@@ -150,6 +182,14 @@ def test_get_yesterday_missed_items_excludes_habits_not_scheduled_yesterday(db_s
     assert missed == []
 
 
+def test_get_yesterday_missed_items_excludes_already_failed(db_session, test_user):
+    habit = _make_habit(db_session, test_user.id)
+    _fail(db_session, habit.id, date.today() - timedelta(days=1))
+
+    missed = log_service.get_yesterday_missed_items(db_session, test_user.id)
+    assert missed == []
+
+
 # ---- get_habit_stats: completion_rate ----
 
 
@@ -168,6 +208,21 @@ def test_get_habit_stats_completion_rate(db_session, test_user):
     assert stats.completion_rate == 80.0
 
 
+def test_get_habit_stats_does_not_count_failed_log_as_checked(db_session, test_user):
+    today = date.today()
+    created_at = datetime.combine(today - timedelta(days=4), datetime.min.time())
+    habit = _make_habit(db_session, test_user.id, created_at=created_at)
+
+    for offset in (4, 3, 1, 0):
+        _check(db_session, habit.id, today - timedelta(days=offset))
+    _fail(db_session, habit.id, today - timedelta(days=2))  # 실패로 확정된 날은 완료로 세지 않는다
+
+    stats = log_service.get_habit_stats(db_session, habit)
+    assert stats.scheduled_days == 5
+    assert stats.checked_days == 4
+    assert stats.completion_rate == 80.0
+
+
 # ---- get_habit_stats: current_streak ----
 
 
@@ -183,6 +238,20 @@ def test_streak_today_unchecked_does_not_break_it(db_session, test_user):
     assert stats.current_streak == 3
 
 
+def test_streak_breaks_on_failed_day(db_session, test_user):
+    today = date.today()
+    created_at = datetime.combine(today - timedelta(days=3), datetime.min.time())
+    habit = _make_habit(db_session, test_user.id, created_at=created_at)
+
+    _check(db_session, habit.id, today - timedelta(days=3))
+    _fail(db_session, habit.id, today - timedelta(days=2))  # 실패 확정은 미체크와 동일하게 스트릭을 끊는다
+    _check(db_session, habit.id, today - timedelta(days=1))
+    _check(db_session, habit.id, today)
+
+    stats = log_service.get_habit_stats(db_session, habit)
+    assert stats.current_streak == 2  # 어제, 오늘만 연속
+
+
 def test_streak_breaks_on_past_miss(db_session, test_user):
     today = date.today()
     created_at = datetime.combine(today - timedelta(days=3), datetime.min.time())
@@ -207,6 +276,90 @@ def test_streak_extends_through_today_when_checked(db_session, test_user):
     assert stats.current_streak == 3
 
 
+# ---- get_habit_stats: xp/level ----
+
+
+def test_get_habit_stats_xp_accumulates_per_check(db_session, test_user):
+    today = date.today()
+    created_at = datetime.combine(today - timedelta(days=3), datetime.min.time())
+    habit = _make_habit(db_session, test_user.id, created_at=created_at)
+
+    for offset in (3, 2, 1, 0):
+        _check(db_session, habit.id, today - timedelta(days=offset))
+
+    stats = log_service.get_habit_stats(db_session, habit)
+    assert stats.level_info.xp == 40  # 4회 체크 * XP_PER_CHECK(10), 마일스톤 미달성
+
+
+def test_get_habit_stats_consecutive_misses_accelerate_xp_loss(db_session, test_user):
+    today = date.today()
+    created_at = datetime.combine(today - timedelta(days=9), datetime.min.time())
+    habit = _make_habit(db_session, test_user.id, created_at=created_at)
+
+    # day-9 ~ day-3: 7일 연속 체크 (마일스톤 7일 보너스 +20 발생)
+    for offset in range(9, 2, -1):
+        _check(db_session, habit.id, today - timedelta(days=offset))
+    # day-2, day-1: 2일 연속 미체크 (오늘(offset 0)은 아직 안 지났으니 페널티 없음)
+
+    stats = log_service.get_habit_stats(db_session, habit)
+    # 90(=7*10+20) - 8(1회 연속 미스) - 16(2회 연속 미스, 가속) = 66
+    assert stats.level_info.xp == 66
+
+
+def test_get_habit_stats_xp_floors_at_zero(db_session, test_user):
+    today = date.today()
+    created_at = datetime.combine(today - timedelta(days=5), datetime.min.time())
+    habit = _make_habit(db_session, test_user.id, created_at=created_at)
+    # 아무것도 체크하지 않음 -> 5일 연속 미스, 페널티가 계속 누적돼도 xp는 0 밑으로 내려가지 않는다.
+
+    stats = log_service.get_habit_stats(db_session, habit)
+    assert stats.level_info.xp == 0
+    assert stats.level_info.level == 1
+
+
+def test_get_habit_stats_xp_freezes_after_completion(db_session, test_user):
+    today = date.today()
+    created_at = datetime.combine(today - timedelta(days=10), datetime.min.time())
+    habit = _make_habit(db_session, test_user.id, created_at=created_at)
+    for offset in range(10, 5, -1):  # day-10 ~ day-6, 5일 연속 체크
+        _check(db_session, habit.id, today - timedelta(days=offset))
+
+    habit.status = HabitStatus.COMPLETED
+    habit.completed_at = datetime.combine(today - timedelta(days=6), datetime.min.time())  # 마지막 체크일에 완료 처리
+    db_session.commit()
+    db_session.refresh(habit)
+
+    # 완료 이후 6일(day-5 ~ 오늘)은 전부 미체크 상태로 지나갔지만, 동결되어 페널티가 반영되지 않아야 한다.
+    # (동결이 없었다면 6일 연속 미스로 xp가 0까지 깎였을 것)
+    stats = log_service.get_habit_stats(db_session, habit)
+    assert stats.level_info.xp == 50
+
+
+# ---- get_account_level ----
+
+
+def test_get_account_level_sums_xp_across_habits(db_session, test_user):
+    today = date.today()
+    habit_a = _make_habit(db_session, test_user.id, name="A", created_at=datetime.combine(today, datetime.min.time()))
+    habit_b = _make_habit(db_session, test_user.id, name="B", created_at=datetime.combine(today, datetime.min.time()))
+    _check(db_session, habit_a.id, today)
+    _check(db_session, habit_b.id, today)
+
+    account_level = log_service.get_account_level(db_session, test_user.id)
+    assert account_level.xp == 20  # 두 습관 각각 10xp
+
+
+def test_get_account_level_scoped_to_user(db_session, test_user, other_user):
+    today = date.today()
+    mine = _make_habit(db_session, test_user.id, created_at=datetime.combine(today, datetime.min.time()))
+    _check(db_session, mine.id, today)
+    others = _make_habit(db_session, other_user.id, created_at=datetime.combine(today, datetime.min.time()))
+    _check(db_session, others.id, today)
+
+    account_level = log_service.get_account_level(db_session, test_user.id)
+    assert account_level.xp == 10
+
+
 # ---- get_monthly_summary ----
 
 
@@ -245,6 +398,15 @@ def test_get_monthly_summary_counts_checked_habits(db_session, test_user):
     assert by_date[date(2026, 3, 6)].checked_count == 0
 
 
+def test_get_monthly_summary_does_not_count_failed_as_checked(db_session, test_user):
+    habit = _make_habit(db_session, test_user.id, created_at=datetime(2026, 3, 1))
+    _fail(db_session, habit.id, date(2026, 3, 5))
+
+    summaries = log_service.get_monthly_summary(db_session, test_user.id, 2026, 3)
+    by_date = {s.log_date: s for s in summaries}
+    assert by_date[date(2026, 3, 5)].checked_count == 0
+
+
 # ---- summarize_completion_rate: 미래 날짜 제외 회귀 테스트 ----
 # CLAUDE.md에 기록된 실제 버그: 미래 날짜를 포함시키면 완료율이 부당하게 낮게 나온다
 # (실제로 6.2% -> 수정 후 50%가 된 사례).
@@ -321,6 +483,17 @@ def test_get_weekly_matrix_marks_pre_creation_days_as_none(db_session, test_user
     assert row.checks[date(2020, 1, 8).isoformat()] is False  # 생성일(수), 미체크
 
 
+def test_get_weekly_matrix_treats_failed_day_as_unchecked(db_session, test_user):
+    week_start = date(2020, 1, 6)  # 월요일, 확실한 과거
+    habit = _make_habit(db_session, test_user.id, created_at=datetime(2020, 1, 6))
+    _fail(db_session, habit.id, date(2020, 1, 6))
+
+    rows = log_service.get_weekly_matrix(db_session, test_user.id, week_start)
+    row = next(r for r in rows if r.habit_id == habit.id)
+
+    assert row.checks[date(2020, 1, 6).isoformat()] is False
+
+
 def test_get_weekly_matrix_completion_rate_counts_only_past_days(db_session, test_user):
     week_start = date(2020, 1, 6)  # 완전히 과거인 주
     habit = _make_habit(db_session, test_user.id, created_at=datetime(2020, 1, 6))