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/main.py

@@ -0,0 +1,77 @@
+import logging
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI, Request
+from fastapi.responses import FileResponse, JSONResponse
+from fastapi.staticfiles import StaticFiles
+from starlette.exceptions import HTTPException as StarletteHTTPException
+from starlette.middleware.sessions import SessionMiddleware
+
+from app.config import settings
+from app.database import SessionLocal
+from app.routers import auth, habits, logs, pages, push
+from app.routers.pages import templates
+from app.security import get_current_user_optional
+from app.services import scheduler_service
+
+logger = logging.getLogger(__name__)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    scheduler_service.start_scheduler()
+    yield
+    scheduler_service.shutdown_scheduler()
+
+
+app = FastAPI(title="습관 트래커", lifespan=lifespan)
+
+# 구글 OAuth 핸드셰이크 중 state/nonce를 임시로 저장하는 데만 쓰는 세션이다.
+# 로그인 유지용 쿠키(habit_session)와는 별개.
+app.add_middleware(SessionMiddleware, secret_key=settings.secret_key, session_cookie="oauth_session", max_age=600)
+
+app.mount("/static", StaticFiles(directory="app/static"), name="static")
+
+app.include_router(auth.router)
+app.include_router(habits.router)
+app.include_router(logs.router)
+app.include_router(push.router)
+app.include_router(pages.router)
+
+
+def _is_api_path(path: str) -> bool:
+    return path.startswith("/api/") or path.startswith("/static/")
+
+
+def _current_user_context(request: Request) -> dict:
+    db = SessionLocal()
+    try:
+        current_user = get_current_user_optional(request, db)
+    finally:
+        db.close()
+    return {"logged_in": current_user is not None, "current_user": current_user}
+
+
+@app.exception_handler(StarletteHTTPException)
+async def http_exception_handler(request: Request, exc: StarletteHTTPException):
+    if exc.status_code == 404 and not _is_api_path(request.url.path):
+        return templates.TemplateResponse(
+            request, "404.html", _current_user_context(request), status_code=404
+        )
+    return JSONResponse({"detail": exc.detail}, status_code=exc.status_code)
+
+
+@app.exception_handler(Exception)
+async def unhandled_exception_handler(request: Request, exc: Exception):
+    logger.exception("처리되지 않은 오류")
+    if _is_api_path(request.url.path):
+        return JSONResponse({"detail": "서버 오류가 발생했습니다"}, status_code=500)
+    return templates.TemplateResponse(
+        request, "500.html", _current_user_context(request), status_code=500
+    )
+
+
+@app.get("/service-worker.js")
+def service_worker():
+    # 서비스워커 scope가 앱 전체를 커버하려면 /static/ 하위가 아닌 루트 경로로 서빙해야 한다.
+    return FileResponse("app/static/service-worker.js", media_type="application/javascript")