fix: serve browse pages from MinIO cache; fix ReapStaleTasks PocketBase filter

- Runner fetches 9 browse combos (genre×sort×status) every 6h and stores
  JSON snapshots in MinIO libnovel-browse bucket (browse_refresh.go)
- Backend handleBrowse reads page-1 results from MinIO first; falls back
  to live novelfire.net fetch; returns empty+cached:false on total failure
  instead of 502
- Add BrowseStore interface (bookstore.go), MinIO put/get helpers (minio.go),
  Store methods + compile-time assertion (store.go), BucketBrowse config,
  wiring in cmd/backend and cmd/runner, docker-compose-new bucket init
- Fix ReapStaleTasks: PocketBase datetime fields require heartbeat_at=null
  (not heartbeat_at="") in filter expressions, and nil (not "") in patch
  payload — was causing 400 errors on every reap cycle

backend/internal/backend/handlers.go

@@ -204,16 +204,36 @@ func (s *Server) handleBrowse(w http.ResponseWriter, r *http.Request) {
 		pageNum = 1
 	}
 
-	targetURL := fmt.Sprintf("%s/genre-%s/sort-%s/status-%s/%s?page=%d",
-		novelFireBase, genre, sortBy, status, novelType, pageNum)
+	// ── Try MinIO cache first ─────────────────────────────────────────────
+	// Only page 1 is cached; higher pages fall through to live fetch.
+	if pageNum == 1 && s.deps.BrowseStore != nil {
+		if data, ok, err := s.deps.BrowseStore.GetBrowsePage(r.Context(), genre, sortBy, status, novelType, 1); err == nil && ok {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Cache-Control", "public, max-age=300")
+			_, _ = w.Write(data)
+			return
+		}
+	}
 
+	// ── Fall back to live novelfire.net fetch ──────────────────────────────
 	ctx, cancel := context.WithTimeout(r.Context(), 45*time.Second)
 	defer cancel()
 
+	targetURL := fmt.Sprintf("%s/genre-%s/sort-%s/status-%s/%s?page=%d",
+		novelFireBase, genre, sortBy, status, novelType, pageNum)
+
 	novels, hasNext, err := s.fetchBrowsePage(ctx, targetURL)
 	if err != nil {
-		s.deps.Log.Error("handleBrowse: fetch failed", "url", targetURL, "err", err)
-		jsonError(w, http.StatusBadGateway, err.Error())
+		// Live fetch also failed — return empty list with cached=false flag so
+		// the UI can show a "not ready yet" state instead of a hard error.
+		s.deps.Log.Error("handleBrowse: fetch failed (no cache)", "url", targetURL, "err", err)
+		w.Header().Set("Cache-Control", "no-store")
+		writeJSON(w, 0, map[string]any{
+			"novels":  []any{},
+			"page":    pageNum,
+			"hasNext": false,
+			"cached":  false,
+		})
 		return
 	}
 
@@ -222,6 +242,7 @@ func (s *Server) handleBrowse(w http.ResponseWriter, r *http.Request) {
 		"novels":  novels,
 		"page":    pageNum,
 		"hasNext": hasNext,
+		"cached":  false,
 	})
 }
 

backend/internal/backend/server.go

@@ -46,6 +46,8 @@ type Dependencies struct {
 	PresignStore bookstore.PresignStore
 	// ProgressStore reads/writes per-session reading progress.
 	ProgressStore bookstore.ProgressStore
+	// BrowseStore reads cached browse page snapshots from MinIO.
+	BrowseStore bookstore.BrowseStore
 	// Producer creates scrape/audio tasks in PocketBase.
 	Producer taskqueue.Producer
 	// TaskReader reads scrape/audio task records from PocketBase.