Initial commit: habit tracker PWA with Google OAuth, push notifications

FastAPI + SQLAlchemy/Alembic + MariaDB backend with Jinja2/htmx/Alpine
server-rendered frontend. Multi-user via Google OAuth, daily habit
tracking, monthly/weekly history views, Web Push reminders via
APScheduler, and PWA support (manifest, service worker, offline caching).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/services/push_service.py

@@ -0,0 +1,69 @@
+import json
+
+from pywebpush import WebPushException, webpush
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.config import settings
+from app.models.push_subscription import PushSubscription
+from app.schemas.push import PushSubscribeRequest
+
+
+def list_subscriptions(db: Session, user_id: int) -> list[PushSubscription]:
+    return list(db.scalars(select(PushSubscription).where(PushSubscription.user_id == user_id)))
+
+
+def save_subscription(
+    db: Session, user_id: int, data: PushSubscribeRequest, user_agent: str | None = None
+) -> PushSubscription:
+    existing = db.scalar(select(PushSubscription).where(PushSubscription.endpoint == data.endpoint))
+    if existing:
+        existing.user_id = user_id  # 같은 기기에서 다른 유저가 재구독하면 소유자를 갱신한다.
+        existing.p256dh_key = data.keys.p256dh
+        existing.auth_key = data.keys.auth
+        db.commit()
+        return existing
+
+    sub = PushSubscription(
+        user_id=user_id,
+        endpoint=data.endpoint,
+        p256dh_key=data.keys.p256dh,
+        auth_key=data.keys.auth,
+        user_agent=user_agent,
+    )
+    db.add(sub)
+    db.commit()
+    db.refresh(sub)
+    return sub
+
+
+def delete_subscription(db: Session, endpoint: str) -> None:
+    existing = db.scalar(select(PushSubscription).where(PushSubscription.endpoint == endpoint))
+    if existing:
+        db.delete(existing)
+        db.commit()
+
+
+def send_to_user(db: Session, user_id: int, title: str, body: str, url: str = "/today") -> int:
+    """해당 유저의 구독자에게만 알림을 보낸다. 만료된(410/404) 구독은 자동으로 삭제한다. 성공 발송 건수를 반환."""
+    payload = json.dumps({"title": title, "body": body, "url": url}, ensure_ascii=False)
+    sent = 0
+    for sub in list_subscriptions(db, user_id):
+        try:
+            webpush(
+                subscription_info={
+                    "endpoint": sub.endpoint,
+                    "keys": {"p256dh": sub.p256dh_key, "auth": sub.auth_key},
+                },
+                data=payload,
+                vapid_private_key=settings.vapid_private_key,
+                vapid_claims={"sub": settings.vapid_subject},
+            )
+            sent += 1
+        except WebPushException as exc:
+            status_code = exc.response.status_code if exc.response is not None else None
+            if status_code in (404, 410):
+                db.delete(sub)
+                db.commit()
+            # 그 외 오류(일시적 네트워크 문제 등)는 건너뛰고 다음 구독자에게 계속 발송한다.
+    return sent