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/static/service-worker.js

@@ -0,0 +1,103 @@
+const CACHE_NAME = "habit-tracker-v3";
+const APP_SHELL = [
+  "/static/css/style.css",
+  "/static/js/app.js",
+  "/static/js/push-register.js",
+  "/static/js/habit-reorder.js",
+  "/static/js/vendor/htmx.min.js",
+  "/static/js/vendor/alpine.min.js",
+  "/static/js/vendor/sortable.min.js",
+  "/static/icons/icon-192.png",
+  "/static/icons/icon-512.png",
+  "/static/manifest.json",
+];
+
+self.addEventListener("install", (event) => {
+  event.waitUntil(
+    caches
+      .open(CACHE_NAME)
+      .then((cache) => cache.addAll(APP_SHELL))
+      .then(() => self.skipWaiting())
+  );
+});
+
+self.addEventListener("activate", (event) => {
+  event.waitUntil(
+    caches
+      .keys()
+      .then((keys) => Promise.all(keys.filter((key) => key !== CACHE_NAME).map((key) => caches.delete(key))))
+      .then(() => self.clients.claim())
+  );
+});
+
+self.addEventListener("fetch", (event) => {
+  const { request } = event;
+  if (request.method !== "GET") return;
+
+  const url = new URL(request.url);
+  if (url.pathname.startsWith("/api/")) return;
+
+  // 페이지 탐색(/today, /habits, /history 등)은 습관 추가·수정 직후 리다이렉트되는 화면이라
+  // 캐시된 옛 내용이 먼저 보이면 "저장한 게 사라졌다"처럼 보인다. 네트워크를 우선 시도하고
+  // 오프라인일 때만 캐시로 폴백한다.
+  if (request.mode === "navigate") {
+    event.respondWith(
+      fetch(request)
+        .then((response) => {
+          if (response.ok) {
+            const clone = response.clone();
+            caches.open(CACHE_NAME).then((cache) => cache.put(request, clone));
+          }
+          return response;
+        })
+        .catch(() => caches.match(request))
+    );
+    return;
+  }
+
+  // 정적 자산은 캐시 우선 응답 후 백그라운드로 갱신(stale-while-revalidate) — 자주 안 바뀌므로 속도 우선.
+  event.respondWith(
+    caches.match(request).then((cached) => {
+      const network = fetch(request)
+        .then((response) => {
+          if (response.ok) {
+            const clone = response.clone();
+            caches.open(CACHE_NAME).then((cache) => cache.put(request, clone));
+          }
+          return response;
+        })
+        .catch(() => cached);
+      return cached || network;
+    })
+  );
+});
+
+self.addEventListener("push", (event) => {
+  if (!event.data) return;
+  const data = event.data.json();
+  event.waitUntil(
+    self.registration.showNotification(data.title || "습관 트래커", {
+      body: data.body || "",
+      icon: "/static/icons/icon-192.png",
+      badge: "/static/icons/icon-192.png",
+      data: { url: data.url || "/today" },
+    })
+  );
+});
+
+self.addEventListener("notificationclick", (event) => {
+  event.notification.close();
+  const targetUrl = (event.notification.data && event.notification.data.url) || "/today";
+  event.waitUntil(
+    self.clients.matchAll({ type: "window", includeUncontrolled: true }).then((clientsList) => {
+      for (const client of clientsList) {
+        if (client.url.includes(targetUrl) && "focus" in client) {
+          return client.focus();
+        }
+      }
+      if (self.clients.openWindow) {
+        return self.clients.openWindow(targetUrl);
+      }
+    })
+  );
+});