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/runner/browse_refresh.go

@@ -0,0 +1,176 @@
+package runner
+
+// browse_refresh.go — independent 6-hour loop that fetches novelfire.net
+// browse page snapshots and stores them in MinIO.
+//
+// Design:
+//   - Runs on its own ticker (BrowseRefreshInterval, default 6h) inside Run().
+//   - Fetches page 1 for each combination of the standard genre/sort/status
+//     filter values and stores the parsed JSON blob in MinIO via BrowseStore.
+//   - The backend's handleBrowse then serves from MinIO instead of calling
+//     novelfire.net live, which avoids IP-based rate-limiting on the server.
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+)
+
+// browseNovelListing mirrors backend.NovelListing for JSON serialisation.
+type browseNovelListing struct {
+	Slug  string `json:"slug"`
+	Title string `json:"title"`
+	Cover string `json:"cover"`
+	URL   string `json:"url"`
+}
+
+// browseSnapshot is the JSON structure stored in MinIO.
+type browseSnapshot struct {
+	Novels  []browseNovelListing `json:"novels"`
+	Page    int                  `json:"page"`
+	HasNext bool                 `json:"hasNext"`
+	// CachedAt is the UTC time the snapshot was written (ISO 8601).
+	CachedAt string `json:"cachedAt"`
+}
+
+// browseCombos lists the filter combinations to pre-fetch.
+// Each entry is (genre, sort, status, novelType).
+var browseCombos = []struct{ genre, sort, status, novelType string }{
+	{"all", "popular", "all", "all-novel"},
+	{"all", "popular", "ongoing", "all-novel"},
+	{"all", "popular", "completed", "all-novel"},
+	{"all", "new", "all", "all-novel"},
+	{"all", "new", "ongoing", "all-novel"},
+	{"all", "new", "completed", "all-novel"},
+	{"all", "top-rated", "all", "all-novel"},
+	{"all", "top-rated", "ongoing", "all-novel"},
+	{"all", "top-rated", "completed", "all-novel"},
+}
+
+const novelFireBrowseBase = "https://novelfire.net"
+
+// runBrowseRefresh fetches all browse combos from novelfire.net and stores
+// the results in MinIO. Errors per-combo are logged but do not abort the
+// whole refresh cycle.
+func (r *Runner) runBrowseRefresh(ctx context.Context) {
+	if r.deps.BrowseStore == nil {
+		r.deps.Log.Warn("runner: browse refresh skipped — BrowseStore not configured")
+		return
+	}
+
+	log := r.deps.Log.With("op", "browse_refresh")
+	log.Info("runner: browse refresh starting", "combos", len(browseCombos))
+
+	ok, fail := 0, 0
+	for _, c := range browseCombos {
+		if ctx.Err() != nil {
+			break
+		}
+		novels, hasNext, err := fetchBrowsePage(ctx, c.genre, c.sort, c.status, c.novelType)
+		if err != nil {
+			log.Warn("runner: browse fetch failed",
+				"genre", c.genre, "sort", c.sort, "status", c.status, "err", err)
+			fail++
+			continue
+		}
+
+		snap := browseSnapshot{
+			Novels:   novels,
+			Page:     1,
+			HasNext:  hasNext,
+			CachedAt: time.Now().UTC().Format(time.RFC3339),
+		}
+		data, _ := json.Marshal(snap)
+		if err := r.deps.BrowseStore.PutBrowsePage(ctx, c.genre, c.sort, c.status, c.novelType, 1, data); err != nil {
+			log.Warn("runner: browse put failed",
+				"genre", c.genre, "sort", c.sort, "status", c.status, "err", err)
+			fail++
+			continue
+		}
+		ok++
+	}
+
+	log.Info("runner: browse refresh finished", "ok", ok, "failed", fail)
+}
+
+// fetchBrowsePage calls novelfire.net and returns a list of novel listings
+// plus a hasNext flag. Mirrors the logic in backend/handlers.go.
+func fetchBrowsePage(ctx context.Context, genre, sort, status, novelType string) ([]browseNovelListing, bool, error) {
+	pageURL := fmt.Sprintf("%s/genre-%s/sort-%s/status-%s/%s?page=1",
+		novelFireBrowseBase, genre, sort, status, novelType)
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, pageURL, nil)
+	if err != nil {
+		return nil, false, fmt.Errorf("build request: %w", err)
+	}
+	req.Header.Set("User-Agent", "Mozilla/5.0 (compatible; libnovel-runner/2)")
+	req.Header.Set("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8")
+	req.Header.Set("Accept-Language", "en-US,en;q=0.9")
+
+	httpClient := &http.Client{Timeout: 45 * time.Second}
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, false, fmt.Errorf("fetch %s: %w", pageURL, err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		_, _ = io.Copy(io.Discard, resp.Body)
+		return nil, false, fmt.Errorf("upstream returned %d for %s", resp.StatusCode, pageURL)
+	}
+
+	return parseBrowseHTML(resp.Body)
+}
+
+// parseBrowseHTML parses a novelfire HTML response body. Mirrors parseBrowsePage
+// in backend/handlers.go — kept separate to avoid coupling packages.
+func parseBrowseHTML(r io.Reader) ([]browseNovelListing, bool, error) {
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return nil, false, err
+	}
+	body := string(data)
+
+	hasNext := strings.Contains(body, `rel="next"`) ||
+		strings.Contains(body, `aria-label="Next"`) ||
+		strings.Contains(body, `class="next"`)
+
+	slugRe := regexp.MustCompile(`href="/book/([^/"]+)"`)
+	titleRe := regexp.MustCompile(`class="novel-title[^"]*"[^>]*>([^<]+)<`)
+	coverRe := regexp.MustCompile(`data-src="(https?://[^"]+)"`)
+
+	slugMatches := slugRe.FindAllStringSubmatch(body, -1)
+	titleMatches := titleRe.FindAllStringSubmatch(body, -1)
+	coverMatches := coverRe.FindAllStringSubmatch(body, -1)
+
+	var novels []browseNovelListing
+	seen := make(map[string]bool)
+	for i, sm := range slugMatches {
+		slug := sm[1]
+		if seen[slug] {
+			continue
+		}
+		seen[slug] = true
+
+		item := browseNovelListing{
+			Slug: slug,
+			URL:  novelFireBrowseBase + "/book/" + slug,
+		}
+		if i < len(titleMatches) {
+			item.Title = strings.TrimSpace(titleMatches[i][1])
+		}
+		if i < len(coverMatches) {
+			item.Cover = coverMatches[i][1]
+		}
+		if item.Title != "" {
+			novels = append(novels, item)
+		}
+	}
+
+	return novels, hasNext, nil
+}

backend/internal/runner/runner.go

@@ -44,6 +44,9 @@ type Config struct {
 	// StaleTaskThreshold is how old a heartbeat must be (or absent) before the
 	// task is considered orphaned and reset to pending. Defaults to 2m when 0.
 	StaleTaskThreshold time.Duration
+	// BrowseRefreshInterval is how often the runner pre-fetches browse page
+	// snapshots from novelfire.net and stores them in MinIO. Defaults to 6h.
+	BrowseRefreshInterval time.Duration
 }
 
 // Dependencies are the external services the runner depends on.
@@ -56,6 +59,8 @@ type Dependencies struct {
 	BookReader bookstore.BookReader
 	// AudioStore persists generated audio and checks key existence.
 	AudioStore bookstore.AudioStore
+	// BrowseStore stores browse page snapshots in MinIO.
+	BrowseStore bookstore.BrowseStore
 	// Novel is the scraper implementation.
 	Novel scraper.NovelScraper
 	// Kokoro is the TTS client.
@@ -91,6 +96,9 @@ func New(cfg Config, deps Dependencies) *Runner {
 	if cfg.StaleTaskThreshold <= 0 {
 		cfg.StaleTaskThreshold = 2 * time.Minute
 	}
+	if cfg.BrowseRefreshInterval <= 0 {
+		cfg.BrowseRefreshInterval = 6 * time.Hour
+	}
 	if deps.Log == nil {
 		deps.Log = slog.Default()
 	}
@@ -121,6 +129,7 @@ func (r *Runner) Run(ctx context.Context) error {
 		"poll_interval", r.cfg.PollInterval,
 		"max_scrape", r.cfg.MaxConcurrentScrape,
 		"max_audio", r.cfg.MaxConcurrentAudio,
+		"browse_refresh_interval", r.cfg.BrowseRefreshInterval,
 	)
 
 	scrapeSem := make(chan struct{}, r.cfg.MaxConcurrentScrape)
@@ -134,6 +143,12 @@ func (r *Runner) Run(ctx context.Context) error {
 	tick := time.NewTicker(r.cfg.PollInterval)
 	defer tick.Stop()
 
+	browseTick := time.NewTicker(r.cfg.BrowseRefreshInterval)
+	defer browseTick.Stop()
+
+	// Run one browse refresh and one poll immediately on startup.
+	go r.runBrowseRefresh(ctx)
+
 	// Run one poll immediately on startup, then on each tick.
 	for {
 		r.poll(ctx, scrapeSem, audioSem, &wg)
@@ -154,6 +169,8 @@ func (r *Runner) Run(ctx context.Context) error {
 				r.deps.Log.Warn("runner: drain timeout exceeded, forcing exit")
 			}
 			return nil
+		case <-browseTick.C:
+			go r.runBrowseRefresh(ctx)
 		case <-tick.C:
 		}
 	}