fix(subscription): prevent duplicate qb downloads

internal/service/subscription.go

@@ -214,10 +214,7 @@ func (s *SubscriptionService) runOne(ctx context.Context, sub *model.Subscriptio
 
 	queued := 0
 	for _, item := range feed.Channel.Items {
-		guid := item.GUID
-		if guid == "" {
-			guid = item.Link
-		}
+		guid := stableRSSItemGUID(item.Title, item.GUID, item.Link, item.Enclosure.URL)
 		if _, ok := seenSet[guid]; ok {
 			continue
 		}
@@ -253,6 +250,11 @@ func (s *SubscriptionService) runOne(ctx context.Context, sub *model.Subscriptio
 			BackdropURL: sub.BackdropURL,
 			Overview:    sub.Overview,
 		}); err != nil {
+			if errors.Is(err, ErrDownloadAlreadyExists) {
+				seen = append(seen, guid)
+				seenSet[guid] = struct{}{}
+				continue
+			}
 			s.log.Warn("subscription enqueue failed",
 				zap.String("title", item.Title),
 				zap.String("media_type", mediaType),
@@ -338,6 +340,11 @@ func (s *SubscriptionService) runSiteSearch(ctx context.Context, sub *model.Subs
 			BackdropURL: sub.BackdropURL,
 			Overview:    sub.Overview,
 		}); err != nil {
+			if errors.Is(err, ErrDownloadAlreadyExists) {
+				seen = append(seen, candidate.GUID)
+				seenSet[candidate.GUID] = struct{}{}
+				continue
+			}
 			lastEnqueueErr = err
 			s.log.Warn("site-search subscription enqueue failed",
 				zap.String("subscription", sub.Name),
@@ -389,7 +396,7 @@ func selectSiteSearchCandidates(results []SearchResult, sub *model.Subscription,
 		if download == "" {
 			continue
 		}
-		guid := download
+		guid := stableSiteSearchGUID(item, download)
 		if _, ok := seenSet[guid]; ok {
 			continue
 		}
@@ -472,6 +479,68 @@ func selectSiteSearchCandidates(results []SearchResult, sub *model.Subscription,
 	return selected
 }
 
+func stableRSSItemGUID(title, guid, link, enclosureURL string) string {
+	parts := []string{"rss", strings.ToLower(strings.TrimSpace(title))}
+	for _, raw := range []string{guid, enclosureURL, link} {
+		if key := stableDownloadURLKey(raw); key != "" {
+			parts = append(parts, key)
+			return strings.Join(parts, "|")
+		}
+		if raw = strings.TrimSpace(raw); raw != "" {
+			parts = append(parts, strings.ToLower(raw))
+			return strings.Join(parts, "|")
+		}
+	}
+	return strings.Join(parts, "|")
+}
+
+func stableSiteSearchGUID(item SearchResult, download string) string {
+	parts := []string{
+		"site",
+		strings.ToLower(strings.TrimSpace(firstNonEmpty(item.SiteID, item.SiteName))),
+		strings.ToLower(strings.TrimSpace(item.Category)),
+		strings.ToLower(strings.TrimSpace(item.Title)),
+		fmt.Sprintf("%d", item.Size),
+	}
+	if key := stableDownloadURLKey(download); key != "" {
+		parts = append(parts, key)
+	}
+	return strings.Join(parts, "|")
+}
+
+func stableDownloadURLKey(raw string) string {
+	raw = strings.TrimSpace(raw)
+	if raw == "" {
+		return ""
+	}
+	u, err := url.Parse(raw)
+	if err != nil {
+		return strings.ToLower(raw)
+	}
+	if strings.EqualFold(u.Scheme, "magnet") {
+		xt := strings.ToLower(strings.TrimSpace(u.Query().Get("xt")))
+		if xt != "" {
+			return "magnet:" + xt
+		}
+		return strings.ToLower(raw)
+	}
+	if u.Host == "" {
+		return strings.ToLower(raw)
+	}
+	q := u.Query()
+	kept := make([]string, 0, 4)
+	for _, key := range []string{"id", "tid", "torrent", "torrent_id", "torrentid", "hash", "info_hash"} {
+		if value := strings.TrimSpace(q.Get(key)); value != "" {
+			kept = append(kept, key+"="+strings.ToLower(value))
+		}
+	}
+	base := strings.ToLower(strings.TrimRight(u.Host, "/") + "/" + strings.TrimLeft(u.Path, "/"))
+	if len(kept) > 0 {
+		return base + "?" + strings.Join(kept, "&")
+	}
+	return base
+}
+
 // defaultExcludeWords 是参考 MoviePilot 默认过滤的「垃圾版本」排除清单，对所有订阅生效，
 // 与用户自定义排除词合并。拉丁词在 containsAnyExcludeToken 里按词边界匹配以避免子串误伤。
 const defaultExcludeWords = "cam,ts,tc,telesync,telecine,hdcam,hdts,枪版,抢先,抢鲜,预告,trailer,sample"