fix: prevent double-counting of sleep sessions in stats by grouping by start date

backend/app/crud.py

@@ -113,22 +113,27 @@ async def update_session(
     return sleep_session
 
 
-async def get_all_time_stats(session: AsyncSession) -> tuple[int, float]:
-    statement = select(func.count(), func.min(SleepSession.start_time))
+async def get_sleep_counts_by_start_date(
+    session: AsyncSession,
+    from_date: Optional[datetime] = None,
+    to_date: Optional[datetime] = None,
+) -> List[tuple]:
+    if to_date and to_date.hour == 0 and to_date.minute == 0 and to_date.second == 0 and to_date.microsecond == 0:
+        to_date = to_date.replace(hour=23, minute=59, second=59, microsecond=999999)
+
+    query_to_date = to_date.replace(tzinfo=None) if to_date and to_date.tzinfo else to_date
+    query_from_date = from_date.replace(tzinfo=None) if from_date and from_date.tzinfo else from_date
+
+    statement = (
+        select(func.date(SleepSession.start_time), func.count())
+        .group_by(func.date(SleepSession.start_time))
+        .order_by(func.date(SleepSession.start_time).desc())
+    )
+
+    if query_from_date:
+        statement = statement.where(SleepSession.start_time >= query_from_date)
+    if query_to_date:
+        statement = statement.where(SleepSession.start_time <= query_to_date)
+
     result = await session.exec(statement)
-    total_sessions, first_session_time = result.one()
-
-    if total_sessions == 0 or first_session_time is None:
-        return 0, 0.0
-
-    # DB has naive datetimes
-    first_session_time_naive = first_session_time.replace(tzinfo=None)
-    
-    # Get current date (naive for comparison)
-    today_date = datetime.now().date()
-    first_date = first_session_time_naive.date()
-    
-    num_days = (today_date - first_date).days + 1
-    avg_sleeps = total_sessions / num_days if num_days > 0 else 0.0
-    
-    return total_sessions, avg_sleeps
+    return list(result.all())

backend/app/routers/stats.py

@@ -3,7 +3,7 @@ from typing import List, Optional
 from fastapi import APIRouter, Depends, Query
 from sqlmodel.ext.asyncio.session import AsyncSession
 from app.database import get_session
-from app.crud import get_sessions, get_all_time_stats
+from app.crud import get_sessions, get_sleep_counts_by_start_date
 from app.schemas import DailySummaryResponse, TimetableResponse, WakeupBedtimeResponse, SummaryResponse
 from app.utils.time_utils import get_day_night_splits
 
@@ -106,14 +106,26 @@ async def get_summary(
     to_date: datetime,
     session: AsyncSession = Depends(get_session),
 ):
-    sessions, _ = await get_sessions(session, from_date=from_date, to_date=to_date)
-    total_sleeps = len(sessions)
-    
+    # Period Stats
+    period_counts = await get_sleep_counts_by_start_date(session, from_date=from_date, to_date=to_date)
+    total_sleeps = sum(count for _, count in period_counts)
     num_days = (to_date.date() - from_date.date()).days + 1
     avg_sleeps_per_day = total_sleeps / num_days if num_days > 0 else 0.0
-    
-    total_sleeps_all_time, avg_sleeps_per_day_all_time = await get_all_time_stats(session)
-    
+
+    # All-Time Stats
+    all_counts = await get_sleep_counts_by_start_date(session)
+    total_sleeps_all_time = sum(count for _, count in all_counts)
+    avg_sleeps_per_day_all_time = 0.0
+    if all_counts:
+        # counts are ordered by desc date (from crud.py)
+        # so last one is earliest.
+        earliest_date_str = all_counts[-1][0]
+        # SQLite date() returns YYYY-MM-DD string
+        earliest_date = datetime.strptime(earliest_date_str, "%Y-%m-%d").date()
+        today = datetime.now(timezone.utc).date()
+        days_all_time = (today - earliest_date).days + 1
+        avg_sleeps_per_day_all_time = total_sleeps_all_time / days_all_time if days_all_time > 0 else 0.0
+
     return {
         "total_sleeps": total_sleeps,
         "avg_sleeps_per_day": avg_sleeps_per_day,