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

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,