package sections

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"maps"
	"sort"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgxpool"
	"golang.org/x/sync/singleflight"

	"github.com/Silo-Server/silo-server/internal/catalog"
	"github.com/Silo-Server/silo-server/internal/models"
	"github.com/Silo-Server/silo-server/internal/overlays"
	"github.com/Silo-Server/silo-server/internal/recommendations"
	"github.com/Silo-Server/silo-server/internal/sections/recipes"
	"github.com/Silo-Server/silo-server/internal/userstore"
)

// SectionWithItems is a resolved section populated with query results.
type SectionWithItems struct {
	ResolvedSection
	Items      []*models.MediaItem `json:"items"`
	TotalCount int                 `json:"total_count"`
	ItemMeta   map[string]SectionItemMeta
}

// SectionItemMeta carries optional per-item metadata for richer section UIs.
type SectionItemMeta struct {
	SeriesID          *string
	SeriesTitle       string
	SeasonNumber      *int
	EpisodeNumber     *int
	Badges            []string
	PositionSeconds   *float64
	DurationSeconds   *float64
	ProgressUpdatedAt *string
	ItemSource        string    // "in_progress" or "next_up"
	SortTimestamp     time.Time // when the preceding episode was completed (for ordering)
}

const recentSeasonPremiereBadgeWindowDays = 14
const editorialCandidateCacheTTL = 24 * time.Hour

// fetchAllMaxConcurrency bounds how many sections FetchAll resolves in parallel.
// Each concurrent section holds a pgxpool connection, so this is also per-request
// pool pressure: with the default pool of 20 conns (database.max_connections),
// N concurrent home requests can hold up to N*fetchAllMaxConcurrency connections.
// Raised from 4 to 6 to cut the wave count for large home layouts (e.g. 32
// sections: 8 waves → 6) while keeping headroom for a few concurrent home loads
// before the pool saturates. Do not raise further without widening the pool or
// load-testing pool contention.
const fetchAllMaxConcurrency = 6
const slowSectionFetchThreshold = 500 * time.Millisecond
const slowAggregateFetchThreshold = time.Second

type recommendationReader interface {
	GetForYouMain(ctx context.Context, userID int, profileID string, limit int, filter catalog.AccessFilter) (*recommendations.ForYouRow, error)
	GetBecauseYouWatched(ctx context.Context, userID int, profileID, sourceItemID string, limit int, filter catalog.AccessFilter) ([]recommendations.ScoredItem, error)
	GetSimilarUsersLiked(ctx context.Context, userID int, profileID string, limit int, filter catalog.AccessFilter) ([]recommendations.ScoredItem, error)
	GetTasteMatchRow(ctx context.Context, userID int, profileID, genre string, limit int, filter catalog.AccessFilter) (*recommendations.ForYouRow, error)
}

// trendingSnapshotGetter is the read side of the trending snapshot table.
// Satisfied by *TrendingSnapshotRepository.
type trendingSnapshotGetter interface {
	Get(ctx context.Context, source, window string) (TrendingSnapshot, bool, error)
}

// Fetcher runs section queries against the database.
type Fetcher struct {
	pool                 *pgxpool.Pool
	progressFilter       *catalog.ContinueWatchingProgressFilter
	watchlistVisibility  *catalog.WatchlistVisibility
	StoreProvider        userstore.UserStoreProvider
	CollectionRepo       *catalog.LibraryCollectionRepository
	RecommendationRepo   *recommendations.Repo // retained for non-reader call sites
	RecommendationReader recommendationReader
	NextUpRepo           *catalog.NextUpRepository
	AudiobookNextRepo    *catalog.AudiobookNextRepository

	// TrendingSnapshots reads the persisted external-trending snapshots that
	// back the trending_discover section. Nil renders that section empty.
	// Snapshots are produced out-of-band by TrendingRefresher, so the read path
	// never calls the upstream provider.
	TrendingSnapshots trendingSnapshotGetter

	candidateCacheMu sync.Mutex
	candidateCache   *editorialCandidateCache
	candidateGroup   singleflight.Group

	// Clock returns the current time. Defaults to recipes.RealClock{}.
	// Tests inject recipes.FixedClock for deterministic seasonal/editorial behavior.
	Clock recipes.Clock
}

// NewFetcher creates a new section Fetcher.
func NewFetcher(pool *pgxpool.Pool) *Fetcher {
	return &Fetcher{
		pool:                pool,
		progressFilter:      catalog.NewContinueWatchingProgressFilter(pool),
		watchlistVisibility: catalog.NewWatchlistVisibilityFromRepos(catalog.NewItemRepository(pool), catalog.NewEpisodeRepository(pool)),
		Clock:               recipes.RealClock{},
	}
}

type editorialCandidateLoader func(context.Context, string, *int, []int, catalog.AccessFilter) ([]string, error)

type editorialCandidateCache struct {
	mu      sync.RWMutex
	entries map[string]editorialCandidateCacheEntry
}

type editorialCandidateCacheEntry struct {
	candidates []string
	expiresAt  time.Time
}

func newEditorialCandidateCache() *editorialCandidateCache {
	return &editorialCandidateCache{entries: make(map[string]editorialCandidateCacheEntry)}
}

func (c *editorialCandidateCache) get(key string, now time.Time) ([]string, bool) {
	if c == nil {
		return nil, false
	}

	c.mu.RLock()
	entry, ok := c.entries[key]
	c.mu.RUnlock()
	if !ok || !now.Before(entry.expiresAt) {
		return nil, false
	}
	return append([]string(nil), entry.candidates...), true
}

func (c *editorialCandidateCache) set(key string, candidates []string, expiresAt time.Time) {
	if c == nil {
		return
	}

	c.mu.Lock()
	c.entries[key] = editorialCandidateCacheEntry{
		candidates: append([]string(nil), candidates...),
		expiresAt:  expiresAt,
	}
	c.mu.Unlock()
}

func (f *Fetcher) ensureEditorialCandidateCache() *editorialCandidateCache {
	f.candidateCacheMu.Lock()
	defer f.candidateCacheMu.Unlock()
	if f.candidateCache == nil {
		f.candidateCache = newEditorialCandidateCache()
	}
	return f.candidateCache
}

func (f *Fetcher) now() time.Time {
	if f != nil && f.Clock != nil {
		return f.Clock.Now()
	}
	return time.Now()
}

func (f *Fetcher) cachedEditorialCandidates(ctx context.Context, subjectType string, libraryID *int, libraryIDs []int, filter catalog.AccessFilter, ttl time.Duration, loader editorialCandidateLoader) ([]string, error) {
	if ttl <= 0 {
		return loader(ctx, subjectType, libraryID, libraryIDs, filter)
	}

	cache := f.ensureEditorialCandidateCache()
	key := editorialCandidateCacheKey(subjectType, libraryID, libraryIDs, filter)
	now := f.now()
	if candidates, ok := cache.get(key, now); ok {
		return candidates, nil
	}

	value, err, _ := f.candidateGroup.Do(key, func() (any, error) {
		now := f.now()
		if candidates, ok := cache.get(key, now); ok {
			return candidates, nil
		}
		candidates, err := loader(ctx, subjectType, libraryID, libraryIDs, filter)
		if err != nil {
			return nil, err
		}
		cache.set(key, candidates, now.Add(ttl))
		return append([]string(nil), candidates...), nil
	})
	if err != nil {
		return nil, err
	}
	candidates, _ := value.([]string)
	return append([]string(nil), candidates...), nil
}

func editorialCandidateCacheKey(subjectType string, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) string {
	var b strings.Builder
	b.WriteString("subject=")
	b.WriteString(strings.ToLower(strings.TrimSpace(subjectType)))

	b.WriteString("|library=")
	if libraryID == nil {
		b.WriteString("all")
	} else {
		b.WriteString(strconv.Itoa(*libraryID))
	}

	b.WriteString("|libraries=")
	writeOptionalSortedInts(&b, libraryIDs)

	// Serialize the full access scope through the shared catalog helper. The
	// candidate loaders push rating AND excluded media types (via
	// ApplySectionAccessFilter) into their SQL, so the key must capture every
	// boundary; the shared helper guarantees it stays in sync with the other
	// access-scoped caches when AccessFilter grows.
	filter.WriteAccessScopeCacheKey(&b)
	return b.String()
}

func writeOptionalSortedInts(b *strings.Builder, values []int) {
	if values == nil {
		b.WriteString("<nil>")
		return
	}
	if len(values) == 0 {
		b.WriteString("<empty>")
		return
	}
	writeSortedInts(b, values)
}

func writeSortedInts(b *strings.Builder, values []int) {
	if len(values) == 0 {
		return
	}
	sorted := append([]int(nil), values...)
	sort.Ints(sorted)
	for i, value := range sorted {
		if i > 0 {
			b.WriteByte(',')
		}
		b.WriteString(strconv.Itoa(value))
	}
}

// FetchOne runs one section query and returns it with items.
func (f *Fetcher) FetchOne(ctx context.Context, resolved ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) (SectionWithItems, error) {
	start := time.Now()
	var result SectionWithItems
	var err error
	defer func() {
		f.logSlowSectionFetch(resolved, libraryID, libraryIDs, result, time.Since(start), err)
	}()

	if resolved.SectionType == SectionContinueWatching {
		result, err = f.fetchContinueWatchingSection(ctx, resolved, libraryID, libraryIDs, userID, profileID, filter)
		return result, err
	}
	if resolved.SectionType == SectionNextUp {
		result, err = f.fetchNextUpSection(ctx, resolved, libraryID, libraryIDs, userID, profileID, filter)
		return result, err
	}
	if resolved.SectionType == SectionNextInSeries {
		result, err = f.fetchNextInSeriesSection(ctx, resolved, libraryID, libraryIDs, userID, profileID, filter)
		return result, err
	}
	if resolved.SectionType == SectionEditorialSpotlight || resolved.SectionType == SectionGenreRoulette {
		var items []*models.MediaItem
		var total int
		var title string
		if resolved.SectionType == SectionEditorialSpotlight {
			items, total, title, err = f.fetchEditorialSpotlightWithTitle(ctx, resolved, libraryID, libraryIDs, filter)
		} else {
			items, total, title, err = f.fetchGenreRouletteWithTitle(ctx, resolved, libraryID, libraryIDs, filter)
		}
		if err != nil {
			return SectionWithItems{}, err
		}
		if title != "" {
			resolved.Title = title
		}
		result = SectionWithItems{
			ResolvedSection: resolved,
			Items:           items,
			TotalCount:      total,
		}
		return result, nil
	}

	var items []*models.MediaItem
	var total int
	if f.isCacheableSectionType(resolved) {
		// User-agnostic rows share one process-global entry per access scope.
		// getOrRefresh returns a defensive slice copy, so reordering or
		// truncating result.Items below (or in a caller) cannot corrupt the
		// cached entry; the pointed-to *MediaItem must not be mutated in place
		// (see cloneMediaItems). The per-user overlay still runs fresh in
		// buildSectionsResponse.
		key := resolvedListCacheKey(resolved, libraryID, libraryIDs, filter)
		items, total, err = getOrRefresh(ctx, key, f.now(), func(loadCtx context.Context) ([]*models.MediaItem, int, error) {
			return f.fetchSection(loadCtx, resolved, libraryID, libraryIDs, userID, profileID, filter)
		})
	} else {
		items, total, err = f.fetchSection(ctx, resolved, libraryID, libraryIDs, userID, profileID, filter)
	}
	if err != nil {
		return SectionWithItems{}, err
	}

	// Apply seasonal title override when the active theme has a custom name.
	// Done here (rather than inside fetchSeasonalThemed) so the section's
	// stored Title is preserved as the fallback used by callers that bypass
	// SectionWithItems construction.
	if resolved.SectionType == SectionSeasonalThemed && len(items) > 0 {
		if title := f.seasonalTitleOverride(resolved); title != "" {
			resolved.Title = title
		}
	}

	result = SectionWithItems{
		ResolvedSection: resolved,
		Items:           items,
		TotalCount:      total,
	}
	return result, nil
}

func (f *Fetcher) logSlowSectionFetch(resolved ResolvedSection, libraryID *int, libraryIDs []int, result SectionWithItems, duration time.Duration, err error) {
	if duration < slowSectionFetchThreshold {
		return
	}
	attrs := []any{
		"section_id", resolved.ID,
		"type", resolved.SectionType,
		"title", resolved.Title,
		"item_count", len(result.Items),
		"total_count", result.TotalCount,
		"duration_ms", duration.Milliseconds(),
	}
	if libraryID != nil {
		attrs = append(attrs, "library_id", *libraryID)
	}
	if libraryIDs != nil {
		attrs = append(attrs, "library_ids", append([]int(nil), libraryIDs...))
	}
	if err != nil {
		attrs = append(attrs, "error", err)
	}
	slog.Warn("slow section fetch", attrs...)
}

// seasonalTitleOverride returns the per-theme display name override for a
// seasonal section, or "" when no override applies.
func (f *Fetcher) seasonalTitleOverride(resolved ResolvedSection) string {
	if len(resolved.Config) == 0 {
		return ""
	}
	var p recipes.SeasonalThemedParams
	if err := json.Unmarshal(resolved.Config, &p); err != nil {
		return ""
	}
	if len(p.ThemeTitles) == 0 {
		return ""
	}
	now := time.Now()
	if f.Clock != nil {
		now = f.Clock.Now()
	}
	// Same usable filter as fetchSeasonalThemed so the override tracks the
	// theme that actually resolved.
	return recipes.SeasonalTitleOverride(p, now, seasonalThemeHasQuery)
}

func (f *Fetcher) fetchContinueWatchingSection(ctx context.Context, resolved ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) (SectionWithItems, error) {
	if f.StoreProvider == nil || userID <= 0 || profileID == "" {
		return SectionWithItems{
			ResolvedSection: resolved,
			Items:           []*models.MediaItem{},
			TotalCount:      0,
			ItemMeta:        map[string]SectionItemMeta{},
		}, nil
	}

	store, err := f.StoreProvider.ForUser(ctx, userID)
	if err != nil {
		return SectionWithItems{}, fmt.Errorf("getting user store: %w", err)
	}

	limit := resolved.ItemLimit
	if limit <= 0 {
		limit = 20
	}
	continueType := ContinueTypeFromConfig(resolved.Config)

	cfgFilters := ParseConfigFilters(resolved.Config)
	configLibraryIDs := cfgFilters.LibraryIDs()

	effectiveLibID := libraryID
	effectiveLibraryIDs := libraryIDs
	if effectiveLibID == nil && len(configLibraryIDs) > 0 {
		effectiveLibraryIDs = configLibraryIDs
	}

	dismissals := f.listContinueWatchingDismissals(ctx, store, profileID)
	orderedItems := make([]*models.MediaItem, 0, limit)
	itemMeta := make(map[string]SectionItemMeta)

	// Ebook resume points live in ebook_reader_progress rather than the
	// watch-progress store, so reading sections pull from that table and skip
	// the next-up handling below.
	if continueType == ContinueTypeReading {
		orderedItems, err = f.collectContinueProgressItems(ctx, store, profileID, dismissals, continueType, effectiveLibID, effectiveLibraryIDs, filter, limit, orderedItems, itemMeta,
			func(pageLimit, offset int) ([]userstore.WatchProgress, error) {
				entries, err := f.listEbookContinueWatchingProgress(ctx, userID, profileID, pageLimit, offset)
				if err != nil {
					return nil, fmt.Errorf("listing ebook reader progress: %w", err)
				}
				return entries, nil
			})
		if err != nil {
			return SectionWithItems{}, err
		}
		// Manga chapters are ebook items linked to a series; collapse multiple
		// in-progress chapters of the same manga to a single card (keeping the
		// most recently read), mirroring the episode→series collapse. Resolve
		// the linkage into itemMeta so the shared collapse can group by series.
		if len(orderedItems) > 1 {
			f.applyMangaChapterSeriesMeta(ctx, orderedItems, itemMeta)
			orderedItems = collapseContinueWatchingSeriesCandidates(orderedItems, itemMeta)
		}
		return SectionWithItems{
			ResolvedSection: resolved,
			Items:           orderedItems,
			TotalCount:      len(orderedItems),
			ItemMeta:        itemMeta,
		}, nil
	}

	orderedItems, err = f.collectContinueProgressItems(ctx, store, profileID, dismissals, continueType, effectiveLibID, effectiveLibraryIDs, filter, limit, orderedItems, itemMeta,
		func(pageLimit, offset int) ([]userstore.WatchProgress, error) {
			entries, err := store.ListProgress(ctx, profileID, "in_progress", pageLimit, offset)
			if err != nil {
				return nil, fmt.Errorf("listing progress: %w", err)
			}
			return entries, nil
		})
	if err != nil {
		return SectionWithItems{}, err
	}

	nextUpMode := ""
	if ContinueTypeAllowsNextUp(continueType) && !resolved.SuppressNextUp {
		nextUpMode = NextUpMode(ctx, store, profileID)
	}
	if ContinueTypeAllowsNextUp(continueType) && nextUpMode == NextUpModeCombined {
		nextUpItems, nextUpMeta, nextUpErr := f.FetchNextUpItems(ctx, userID, profileID, effectiveLibID, effectiveLibraryIDs, filter, limit)
		if nextUpErr != nil {
			slog.ErrorContext(ctx, "fetching next-up items", "component", "sections", "error", nextUpErr)
		} else {
			orderedItems = append(orderedItems, nextUpItems...)
			maps.Copy(itemMeta, nextUpMeta)
		}
	}

	if nextUpMode == NextUpModeCombined && len(orderedItems) > 1 {
		orderedItems = collapseContinueWatchingSeriesCandidates(orderedItems, itemMeta)
	}

	if nextUpMode == NextUpModeCombined && len(orderedItems) > 1 {
		sort.SliceStable(orderedItems, func(i, j int) bool {
			left := itemMeta[orderedItems[i].ContentID].SortTimestamp
			right := itemMeta[orderedItems[j].ContentID].SortTimestamp
			return left.After(right)
		})
	}

	if orderedItems == nil {
		orderedItems = []*models.MediaItem{}
	}

	return SectionWithItems{
		ResolvedSection: resolved,
		Items:           orderedItems,
		TotalCount:      len(orderedItems),
		ItemMeta:        itemMeta,
	}, nil
}

// collectContinueProgressItems pages through in-progress entries from
// listPage, drops dismissed entries, resolves the remainder to media items,
// and appends them to orderedItems until limit is reached, the source is
// exhausted, or continueProgressMaxScanned entries have been scanned. Paging
// past the requested limit matters because dismissal filtering and
// library/access scoping happen after the source query: trimming at the
// source LIMIT would under-fill the section whenever dismissals exist.
func (f *Fetcher) collectContinueProgressItems(
	ctx context.Context,
	store userstore.UserStore,
	profileID string,
	dismissals catalog.HomeDismissalIndex,
	continueType ContinueType,
	libraryID *int,
	libraryIDs []int,
	filter catalog.AccessFilter,
	limit int,
	orderedItems []*models.MediaItem,
	itemMeta map[string]SectionItemMeta,
	listPage func(pageLimit, offset int) ([]userstore.WatchProgress, error),
) ([]*models.MediaItem, error) {
	// LIMIT/OFFSET pages over a live, updated_at-ordered source: a progress
	// write between page fetches shifts rows across page boundaries, so the
	// same content_id can be returned on two consecutive pages. Track what has
	// already been appended so a card never appears twice in one section.
	seen := make(map[string]struct{}, limit)
	for _, item := range orderedItems {
		seen[item.ContentID] = struct{}{}
	}
	for offset := 0; len(orderedItems) < limit && offset < continueProgressMaxScanned; offset += continueProgressPageSize {
		pageLimit := continueProgressPageSize
		if remaining := continueProgressMaxScanned - offset; remaining < pageLimit {
			pageLimit = remaining
		}
		progressEntries, err := listPage(pageLimit, offset)
		if err != nil {
			return nil, err
		}
		if len(progressEntries) == 0 {
			break
		}
		rawProgressCount := len(progressEntries)
		progressEntries = dismissals.FilterProgress(progressEntries)

		pageItems, pageMeta, err := f.fetchContinueProgressItems(ctx, store, profileID, progressEntries, continueType, libraryID, libraryIDs, filter)
		if err != nil {
			return nil, err
		}
		orderedItems = appendUniqueContinueItems(orderedItems, pageItems, seen, limit)
		maps.Copy(itemMeta, pageMeta)
		if rawProgressCount < pageLimit {
			break
		}
	}
	return orderedItems, nil
}

// appendUniqueContinueItems appends pageItems to orderedItems up to limit,
// skipping content IDs already recorded in seen and recording every appended
// ID. Pages come from a live LIMIT/OFFSET scan, so without this guard an item
// shifted across a page boundary by a concurrent progress write would surface
// twice in the same section.
func appendUniqueContinueItems(orderedItems, pageItems []*models.MediaItem, seen map[string]struct{}, limit int) []*models.MediaItem {
	for _, item := range pageItems {
		if len(orderedItems) >= limit {
			break
		}
		if _, dup := seen[item.ContentID]; dup {
			continue
		}
		seen[item.ContentID] = struct{}{}
		orderedItems = append(orderedItems, item)
	}
	return orderedItems
}

// ebookContinueWatchingProgressQuery lists in-progress ebook resume points for
// Continue Reading. Like the video path (pgstore ListProgress "in_progress"),
// rows the user hid via user_history_hidden_items are excluded while reading
// activity after hidden_before counts again.
var ebookContinueWatchingProgressQuery = fmt.Sprintf(`
	SELECT content_id, progress::double precision, updated_at
	FROM ebook_reader_progress
	WHERE user_id = $1
		AND profile_id = $2
		AND progress > 0
		AND progress < %s
		AND NOT EXISTS (
			SELECT 1
			FROM user_history_hidden_items hhi
			WHERE hhi.user_id = ebook_reader_progress.user_id
				AND hhi.profile_id = ebook_reader_progress.profile_id
				AND hhi.media_item_id = ebook_reader_progress.content_id
				AND ebook_reader_progress.updated_at <= hhi.hidden_before
		)
	ORDER BY updated_at DESC, content_id ASC
	LIMIT $3 OFFSET $4
`, catalog.EbookFinishedProgressThresholdSQL)

func (f *Fetcher) listEbookContinueWatchingProgress(ctx context.Context, userID int, profileID string, limit, offset int) ([]userstore.WatchProgress, error) {
	if f.pool == nil || userID <= 0 || profileID == "" || limit <= 0 {
		return nil, nil
	}

	rows, err := f.pool.Query(ctx, ebookContinueWatchingProgressQuery, userID, profileID, limit, offset)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	entries := make([]userstore.WatchProgress, 0)
	for rows.Next() {
		var contentID string
		var progress float64
		var updatedAt time.Time
		if err := rows.Scan(&contentID, &progress, &updatedAt); err != nil {
			return nil, err
		}
		entries = append(entries, userstore.WatchProgress{
			MediaItemID:     contentID,
			PositionSeconds: progress,
			DurationSeconds: 1,
			UpdatedAt:       updatedAt.UTC().Format(time.RFC3339),
		})
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	return entries, nil
}

const (
	continueProgressPageSize   = 100
	continueProgressMaxScanned = 1000
)

func (f *Fetcher) fetchContinueProgressItems(ctx context.Context, store userstore.UserStore, profileID string, entries []userstore.WatchProgress, continueType ContinueType, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, map[string]SectionItemMeta, error) {
	if len(entries) == 0 {
		return nil, map[string]SectionItemMeta{}, nil
	}

	contentIDs := make([]string, 0, len(entries))
	for _, entry := range entries {
		contentIDs = append(contentIDs, entry.MediaItemID)
	}

	mediaItems, err := f.fetchItemsByContentIDs(ctx, contentIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, nil, err
	}

	episodeItems, episodeMeta, err := f.fetchEpisodeTargetsByContentIDs(ctx, contentIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, nil, err
	}

	itemByID := make(map[string]*models.MediaItem, len(mediaItems)+len(episodeItems))
	for _, item := range mediaItems {
		itemByID[item.ContentID] = item
	}
	for _, item := range episodeItems {
		itemByID[item.ContentID] = item
	}

	matchingEntries := make([]userstore.WatchProgress, 0, len(entries))
	hasEpisodeEntries := false
	for _, entry := range entries {
		item, ok := itemByID[entry.MediaItemID]
		if !ok || !ContinueTypeMatchesItem(continueType, item.Type) {
			continue
		}
		if item.Type == "episode" {
			hasEpisodeEntries = true
		}
		matchingEntries = append(matchingEntries, entry)
	}
	if ContinueTypeAllowsNextUp(continueType) && hasEpisodeEntries {
		supersededEpisodeProgress, err := f.progressFilter.SupersededEpisodeProgressIDs(ctx, store, profileID, matchingEntries)
		if err != nil {
			return nil, nil, err
		}
		matchingEntries = catalog.FilterSupersededProgress(matchingEntries, supersededEpisodeProgress)
	}

	itemMeta := make(map[string]SectionItemMeta, len(matchingEntries))
	orderedItems := make([]*models.MediaItem, 0, len(matchingEntries))
	for _, entry := range matchingEntries {
		item, ok := itemByID[entry.MediaItemID]
		if !ok {
			continue
		}
		meta := episodeMeta[entry.MediaItemID]
		position := entry.PositionSeconds
		duration := entry.DurationSeconds
		meta.PositionSeconds = &position
		meta.DurationSeconds = &duration
		progressUpdatedAt := entry.UpdatedAt
		meta.ProgressUpdatedAt = &progressUpdatedAt
		meta.ItemSource = "in_progress"
		if updatedAt, parseErr := time.Parse(time.RFC3339, entry.UpdatedAt); parseErr == nil {
			meta.SortTimestamp = updatedAt
		}
		itemMeta[entry.MediaItemID] = meta
		orderedItems = append(orderedItems, item)
	}

	return orderedItems, itemMeta, nil
}

func (f *Fetcher) fetchNextUpSection(ctx context.Context, resolved ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) (SectionWithItems, error) {
	emptyResult := SectionWithItems{
		ResolvedSection: resolved,
		Items:           []*models.MediaItem{},
		TotalCount:      0,
		ItemMeta:        map[string]SectionItemMeta{},
	}

	if f.StoreProvider == nil || userID <= 0 || profileID == "" {
		return emptyResult, nil
	}

	store, err := f.StoreProvider.ForUser(ctx, userID)
	if err != nil {
		return SectionWithItems{}, fmt.Errorf("getting user store: %w", err)
	}

	// Only resolve if the profile's preference is "separate"
	if NextUpMode(ctx, store, profileID) != NextUpModeSeparate {
		return emptyResult, nil
	}

	limit := resolved.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	items, meta, err := f.FetchNextUpItems(ctx, userID, profileID, libraryID, libraryIDs, filter, limit)
	if err != nil {
		return SectionWithItems{}, err
	}
	if items == nil {
		items = []*models.MediaItem{}
	}
	if meta == nil {
		meta = map[string]SectionItemMeta{}
	}

	return SectionWithItems{
		ResolvedSection: resolved,
		Items:           items,
		TotalCount:      len(items),
		ItemMeta:        meta,
	}, nil
}

// FetchNextUpItems returns the next unwatched episode per series for the given user profile.
// It delegates to NextUpRepository for the optimized LATERAL JOIN query, then resolves
// the full MediaItem objects via fetchEpisodeTargetsByContentIDs.
func (f *Fetcher) FetchNextUpItems(ctx context.Context, userID int, profileID string, libraryID *int, libraryIDs []int, filter catalog.AccessFilter, limit int) ([]*models.MediaItem, map[string]SectionItemMeta, error) {
	if f.NextUpRepo == nil {
		return nil, nil, nil
	}

	results, err := f.NextUpRepo.ListNextUp(ctx, catalog.NextUpQuery{
		UserID:     userID,
		ProfileID:  profileID,
		LibraryID:  libraryID,
		LibraryIDs: libraryIDs,
		Limit:      limit,
	})
	if err != nil {
		return nil, nil, err
	}
	if len(results) == 0 {
		return nil, nil, nil
	}
	results = f.filterNextUpDismissals(ctx, userID, profileID, results)
	if len(results) == 0 {
		return nil, nil, nil
	}

	contentIDs := make([]string, len(results))
	resultByID := make(map[string]catalog.NextUpResult, len(results))
	for i, res := range results {
		contentIDs[i] = res.ContentID
		resultByID[res.ContentID] = res
	}

	episodeItems, episodeMeta, err := f.fetchEpisodeTargetsByContentIDs(ctx, contentIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, nil, fmt.Errorf("fetching episode targets for next-up: %w", err)
	}

	itemByID := make(map[string]*models.MediaItem, len(episodeItems))
	for _, item := range episodeItems {
		itemByID[item.ContentID] = item
	}

	meta := make(map[string]SectionItemMeta, len(results))
	orderedItems := make([]*models.MediaItem, 0, len(results))
	for _, res := range results {
		m, ok := episodeMeta[res.ContentID]
		if !ok {
			continue
		}
		m.ItemSource = "next_up"
		m.SortTimestamp = res.CompletedAt
		meta[res.ContentID] = m

		item, ok := itemByID[res.ContentID]
		if !ok {
			continue
		}
		orderedItems = append(orderedItems, item)
	}

	return orderedItems, meta, nil
}

// fetchNextInSeriesSection surfaces the next unstarted audiobook per series
// the profile has finished a book of. Candidates come from AudiobookNextRepo
// with library scoping pushed into the SQL — otherwise finished series whose
// next book lives in another library would consume the candidate limit and
// starve a library-scoped section. Content-rating access filtering happens
// while resolving candidate IDs to items, so the candidate query still
// over-fetches to compensate for that post-resolution trim.
func (f *Fetcher) fetchNextInSeriesSection(ctx context.Context, resolved ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) (SectionWithItems, error) {
	emptyResult := SectionWithItems{
		ResolvedSection: resolved,
		Items:           []*models.MediaItem{},
		TotalCount:      0,
		ItemMeta:        map[string]SectionItemMeta{},
	}

	if f.AudiobookNextRepo == nil || userID <= 0 || profileID == "" {
		return emptyResult, nil
	}

	limit := resolved.ItemLimit
	if limit <= 0 {
		limit = 20
	}
	candidateLimit := limit * 3
	if candidateLimit > 100 {
		candidateLimit = 100
	}

	results, err := f.AudiobookNextRepo.ListNextInSeries(ctx, catalog.NextInSeriesQuery{
		UserID:             userID,
		ProfileID:          profileID,
		Limit:              candidateLimit,
		LibraryID:          libraryID,
		LibraryIDs:         effectiveFetchLibraryIDs(libraryIDs, filter),
		DisabledLibraryIDs: filter.DisabledLibraryIDs,
	})
	if err != nil {
		return SectionWithItems{}, err
	}
	if len(results) == 0 {
		return emptyResult, nil
	}

	contentIDs := make([]string, len(results))
	for i, res := range results {
		contentIDs[i] = res.ContentID
	}

	items, err := f.fetchItemsByContentIDs(ctx, contentIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return SectionWithItems{}, fmt.Errorf("fetching next-in-series items: %w", err)
	}

	itemByID := make(map[string]*models.MediaItem, len(items))
	for _, item := range items {
		itemByID[item.ContentID] = item
	}

	meta := make(map[string]SectionItemMeta, len(results))
	ordered := make([]*models.MediaItem, 0, limit)
	for _, res := range results {
		if len(ordered) >= limit {
			break
		}
		item, ok := itemByID[res.ContentID]
		if !ok {
			continue
		}
		m := SectionItemMeta{
			SeriesTitle:   res.SeriesName,
			ItemSource:    "next_in_series",
			SortTimestamp: res.LastFinishedAt,
		}
		if res.SeriesIndex != nil {
			if n := int(*res.SeriesIndex); float64(n) == *res.SeriesIndex {
				m.Badges = append(m.Badges, fmt.Sprintf("Book %d", n))
			}
		}
		meta[res.ContentID] = m
		ordered = append(ordered, item)
	}

	return SectionWithItems{
		ResolvedSection: resolved,
		Items:           ordered,
		TotalCount:      len(ordered),
		ItemMeta:        meta,
	}, nil
}

func collapseContinueWatchingSeriesCandidates(items []*models.MediaItem, meta map[string]SectionItemMeta) []*models.MediaItem {
	selectedBySeries := make(map[string]int)
	result := make([]*models.MediaItem, 0, len(items))

	for _, item := range items {
		if item == nil {
			continue
		}

		itemMeta := meta[item.ContentID]
		if itemMeta.SeriesID == nil || *itemMeta.SeriesID == "" {
			result = append(result, item)
			continue
		}

		seriesID := *itemMeta.SeriesID
		selectedIndex, ok := selectedBySeries[seriesID]
		if !ok {
			selectedBySeries[seriesID] = len(result)
			result = append(result, item)
			continue
		}

		current := result[selectedIndex]
		if continueWatchingCandidatePreferred(itemMeta, meta[current.ContentID]) {
			result[selectedIndex] = item
		}
	}

	return result
}

func continueWatchingCandidatePreferred(candidate, current SectionItemMeta) bool {
	candidateInProgress := candidate.ItemSource == "in_progress"
	currentInProgress := current.ItemSource == "in_progress"
	if candidateInProgress != currentInProgress {
		return candidateInProgress
	}

	if candidateInProgress {
		if !candidate.SortTimestamp.Equal(current.SortTimestamp) {
			return candidate.SortTimestamp.After(current.SortTimestamp)
		}
		return episodeOrdinal(candidate) > episodeOrdinal(current)
	}

	return candidate.SortTimestamp.After(current.SortTimestamp)
}

func episodeOrdinal(meta SectionItemMeta) int {
	season := 0
	if meta.SeasonNumber != nil {
		season = *meta.SeasonNumber
	}
	episode := 0
	if meta.EpisodeNumber != nil {
		episode = *meta.EpisodeNumber
	}
	return season*100000 + episode
}

func (f *Fetcher) listContinueWatchingDismissals(ctx context.Context, store userstore.UserStore, profileID string) catalog.HomeDismissalIndex {
	dismissals, err := store.ListHomeDismissals(ctx, profileID, userstore.HomeSurfaceContinueWatching)
	if err != nil {
		slog.ErrorContext(ctx, "listing continue watching dismissals", "component", "sections", "profile_id", profileID, "error", err)
		return catalog.HomeDismissalIndex{}
	}
	return catalog.NewHomeDismissalIndex(dismissals)
}

func (f *Fetcher) filterNextUpDismissals(ctx context.Context, userID int, profileID string, results []catalog.NextUpResult) []catalog.NextUpResult {
	if len(results) == 0 || f.StoreProvider == nil || userID <= 0 || profileID == "" {
		return results
	}

	store, err := f.StoreProvider.ForUser(ctx, userID)
	if err != nil {
		slog.ErrorContext(ctx, "getting user store for next-up dismissals", "component", "sections", "profile_id", profileID, "error", err)
		return results
	}

	dismissals, err := store.ListHomeDismissals(ctx, profileID, userstore.HomeSurfaceNextUp)
	if err != nil {
		slog.ErrorContext(ctx, "listing next-up dismissals", "component", "sections", "profile_id", profileID, "error", err)
		return results
	}
	if len(dismissals) == 0 {
		return results
	}

	dismissedIDs := make(map[string]struct{}, len(dismissals))
	for _, dismissal := range dismissals {
		dismissedIDs[dismissal.MediaItemID] = struct{}{}
	}

	filtered := make([]catalog.NextUpResult, 0, len(results))
	for _, result := range results {
		if _, dismissed := dismissedIDs[result.ContentID]; dismissed {
			continue
		}
		filtered = append(filtered, result)
	}
	return filtered
}

// FetchAll runs all section queries in parallel and returns sections with items.
func (f *Fetcher) FetchAll(ctx context.Context, resolved []ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) []SectionWithItems {
	start := time.Now()
	results := fetchAllWithRunner(ctx, resolved, fetchAllMaxConcurrency, func(ctx context.Context, sec ResolvedSection) (SectionWithItems, error) {
		return f.FetchOne(ctx, sec, libraryID, libraryIDs, userID, profileID, filter)
	})
	duration := time.Since(start)
	if duration >= slowAggregateFetchThreshold {
		attrs := []any{
			"section_count", len(resolved),
			"duration_ms", duration.Milliseconds(),
		}
		if libraryID != nil {
			attrs = append(attrs, "library_id", *libraryID)
		}
		if libraryIDs != nil {
			attrs = append(attrs, "library_ids", append([]int(nil), libraryIDs...))
		}
		slog.WarnContext(ctx, "slow aggregate section fetch", append([]any{"component", "sections"}, attrs...)...)
	}
	return results
}

type sectionFetchRunner func(context.Context, ResolvedSection) (SectionWithItems, error)

func fetchAllWithRunner(ctx context.Context, resolved []ResolvedSection, maxConcurrency int, runner sectionFetchRunner) []SectionWithItems {
	if maxConcurrency <= 0 {
		maxConcurrency = 1
	}

	results := make([]SectionWithItems, len(resolved))
	sem := make(chan struct{}, maxConcurrency)
	var wg sync.WaitGroup

	for i, sec := range resolved {
		i, sec := i, sec
		wg.Add(1)
		go func() {
			defer wg.Done()
			sem <- struct{}{}
			defer func() { <-sem }()

			result, err := runner(ctx, sec)
			if err != nil {
				slog.ErrorContext(ctx, "fetching section items", "component", "sections", "section_id", sec.ID, "type", sec.SectionType, "error", err)
				result = SectionWithItems{
					ResolvedSection: sec,
					Items:           []*models.MediaItem{},
				}
			}
			results[i] = result
		}()
	}

	wg.Wait()
	return results
}

// FetchItemsByContentIDs resolves content IDs to full MediaItem objects,
// applying the provided access filter across libraries.
func (f *Fetcher) FetchItemsByContentIDs(ctx context.Context, contentIDs []string, filter catalog.AccessFilter) ([]*models.MediaItem, error) {
	return f.fetchItemsByContentIDs(ctx, contentIDs, nil, nil, filter)
}

// FetchEpisodesByContentIDs resolves episode content IDs to MediaItem objects
// with their parent series metadata. Returns the items and per-episode metadata
// (series title, season/episode numbers). Non-episode content IDs are silently ignored.
func (f *Fetcher) FetchEpisodesByContentIDs(ctx context.Context, contentIDs []string, filter catalog.AccessFilter) ([]*models.MediaItem, map[string]SectionItemMeta, error) {
	return f.fetchEpisodeTargetsByContentIDs(ctx, contentIDs, nil, nil, filter)
}

// ListOverlaySummaries batches file lookups for section cards and derives the
// compact overlay summary per content ID.
func (f *Fetcher) ListOverlaySummaries(ctx context.Context, contentIDs []string, filter catalog.AccessFilter) (map[string]*models.OverlaySummary, error) {
	summaries := make(map[string]*models.OverlaySummary, len(contentIDs))
	if len(contentIDs) == 0 {
		return summaries, nil
	}

	rows, err := f.pool.Query(ctx, `
		SELECT content_id, episode_id, file_path, resolution, codec_audio, audio_tracks, hdr, video_tracks,
		       codec_video, audio_channels, container, subtitle_tracks, external_subtitles, edition_key
		FROM media_files
		WHERE (content_id = ANY($1) OR episode_id = ANY($1)) AND missing_since IS NULL
		ORDER BY content_id ASC, episode_id ASC, id ASC
	`, contentIDs)
	if err != nil {
		return nil, fmt.Errorf("querying overlay summaries: %w", err)
	}
	defer rows.Close()

	requested := make(map[string]struct{}, len(contentIDs))
	for _, contentID := range contentIDs {
		requested[contentID] = struct{}{}
	}

	grouped := make(map[string][]*models.MediaFile, len(contentIDs))
	for rows.Next() {
		var contentID string
		var episodeID *string
		var filePath string
		var resolution *string
		var codecAudio *string
		var audioTracksJSON []byte
		var hdr bool
		var videoTracksJSON []byte
		var codecVideo *string
		var audioChannels *int
		var container *string
		var subtitleTracksJSON []byte
		var externalSubtitlesJSON []byte
		var editionKey *string

		if err := rows.Scan(
			&contentID, &episodeID, &filePath, &resolution, &codecAudio, &audioTracksJSON, &hdr, &videoTracksJSON,
			&codecVideo, &audioChannels, &container, &subtitleTracksJSON, &externalSubtitlesJSON, &editionKey,
		); err != nil {
			return nil, fmt.Errorf("scanning overlay summary row: %w", err)
		}

		file := &models.MediaFile{
			ContentID: contentID,
			FilePath:  filePath,
			HDR:       hdr,
		}
		if episodeID != nil {
			file.EpisodeID = *episodeID
		}
		if resolution != nil {
			file.Resolution = *resolution
		}
		if codecAudio != nil {
			file.CodecAudio = *codecAudio
		}
		if codecVideo != nil {
			file.CodecVideo = *codecVideo
		}
		if audioChannels != nil {
			file.AudioChannels = *audioChannels
		}
		if container != nil {
			file.Container = *container
		}
		if editionKey != nil {
			file.EditionKey = *editionKey
		}
		if len(audioTracksJSON) > 0 {
			if err := json.Unmarshal(audioTracksJSON, &file.AudioTracks); err != nil {
				return nil, fmt.Errorf("unmarshaling overlay audio tracks: %w", err)
			}
		}
		if len(videoTracksJSON) > 0 {
			if err := json.Unmarshal(videoTracksJSON, &file.VideoTracks); err != nil {
				return nil, fmt.Errorf("unmarshaling overlay video tracks: %w", err)
			}
		}
		if len(subtitleTracksJSON) > 0 {
			if err := json.Unmarshal(subtitleTracksJSON, &file.SubtitleTracks); err != nil {
				return nil, fmt.Errorf("unmarshaling overlay subtitle tracks: %w", err)
			}
		}
		if len(externalSubtitlesJSON) > 0 {
			if err := json.Unmarshal(externalSubtitlesJSON, &file.ExternalSubtitles); err != nil {
				return nil, fmt.Errorf("unmarshaling overlay external subtitles: %w", err)
			}
		}

		groupKey := contentID
		if episodeID != nil {
			if _, ok := requested[*episodeID]; ok {
				groupKey = *episodeID
			}
		}
		grouped[groupKey] = append(grouped[groupKey], file)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterating overlay summary rows: %w", err)
	}

	for contentID, files := range grouped {
		files = catalog.FilterMediaFilesByAccess(files, filter)
		if summary := overlays.BuildSummary(files); summary != nil {
			summaries[contentID] = summary
		}
	}

	return summaries, nil
}

// userAgnosticSectionFetch is the signature shared by every fetch helper whose
// membership is identical for all profiles with the same access scope: no
// userID, no profileID. The signature is the enforcement mechanism for the
// shared resolved-list cache — a helper cannot start reading per-profile state
// without changing its signature, dropping out of userAgnosticSectionFetcher,
// and forcing an explicit new cacheability decision at compile time.
type userAgnosticSectionFetch func(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error)

// userAgnosticSectionFetcher returns the fetch function for section types whose
// shared item list may be cached across profiles, or nil for every other type.
// It is the single source of truth for that decision: fetchSection dispatches
// through it AND isCacheableSectionType derives cache eligibility from it, so
// the two can never disagree.
//
// Deliberately absent despite having the user-agnostic signature:
//   - SectionRandom — user-agnostic but must reshuffle per request;
//   - SectionEditorialSpotlight — has its own candidate cache + rotation and a
//     dedicated FetchOne branch;
//   - SectionGenre / SectionCustomFilter — fetchFiltered shares the signature,
//     but a user-supplied QueryDefinition can carry personalized rules, so
//     cacheability needs the dynamic IsPersonalized check in
//     isCacheableSectionType (dispatch stays in fetchSection's switch);
//   - SectionCollection — user vs library collections are decided by config,
//     handled dynamically in isCacheableSectionType.
func (f *Fetcher) userAgnosticSectionFetcher(t SectionType) userAgnosticSectionFetch {
	switch t {
	case SectionRecentlyAdded:
		return f.fetchRecentlyAdded
	case SectionRecentlyReleased:
		return f.fetchRecentlyReleased
	case SectionCriticallyAcclaimed:
		return f.fetchCriticallyAcclaimed
	case SectionAwardWinners:
		// fetchAwardWinners derives everything from the section config; adapt
		// it to the shared signature.
		return func(ctx context.Context, s ResolvedSection, _ *int, _ []int, _ catalog.AccessFilter) ([]*models.MediaItem, int, error) {
			return f.fetchAwardWinners(ctx, s)
		}
	case SectionFormatShowcase:
		return f.fetchFormatShowcase
	case SectionSeasonalThemed:
		return f.fetchSeasonalThemed
	case SectionMoodCollection:
		return f.fetchMoodCollection
	case SectionTrendingOnServer:
		return f.fetchTrending
	case SectionNewToLibrary:
		return f.fetchNewToLibrary
	case SectionMostWatched:
		return f.fetchMostWatched
	case SectionTrendingDiscover:
		return f.fetchTrendingDiscover
	case SectionAdminCuratedList:
		return f.fetchAdminCuratedList
	case SectionShortWatches:
		return f.fetchShortWatches
	case SectionAnniversaries:
		return f.fetchAnniversaries
	default:
		return nil
	}
}

func (f *Fetcher) fetchSection(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	if fetch := f.userAgnosticSectionFetcher(s.SectionType); fetch != nil {
		return fetch(ctx, s, libraryID, libraryIDs, filter)
	}
	switch s.SectionType {
	case SectionGenre, SectionCustomFilter:
		return f.fetchFiltered(ctx, s, libraryID, libraryIDs, filter)
	case SectionRandom:
		return f.fetchRandom(ctx, s, libraryID, libraryIDs, filter)
	case SectionCollection:
		return f.fetchCollection(ctx, s, libraryID, libraryIDs, userID, profileID, filter)
	case SectionRecommendedForYou, SectionBecauseYouWatched, SectionSimilarUsersLiked, SectionTasteMatch:
		return f.fetchRecommendationSection(ctx, s, libraryID, libraryIDs, userID, profileID, filter)
	case SectionHiddenGems:
		return f.fetchHiddenGems(ctx, s, libraryID, libraryIDs, userID, profileID, filter)
	case SectionForgottenFavorites:
		return f.fetchForgottenFavorites(ctx, s, libraryID, libraryIDs, userID, profileID, filter)
	case SectionEditorialSpotlight:
		return f.fetchEditorialSpotlight(ctx, s, libraryID, libraryIDs, filter)
	case SectionGenreRoulette:
		return f.fetchGenreRoulette(ctx, s, libraryID, libraryIDs, filter)
	case SectionReturningShows:
		return f.fetchReturningShows(ctx, s, libraryID, libraryIDs, userID, profileID, filter)
	case SectionProfileActivityFeed:
		return f.fetchProfileActivityFeed(ctx, s, libraryID, libraryIDs, profileID, filter)
	case SectionWatchlist, SectionFavorites:
		return f.fetchPersonalListSection(ctx, s, libraryID, libraryIDs, userID, profileID, filter)
	default:
		return nil, 0, fmt.Errorf("unsupported section type: %s", s.SectionType)
	}
}

func (f *Fetcher) fetchCollection(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	cfg := ParseCollectionConfig(s.Config)

	// User collection path: resolve from the user's personal store.
	if userCollID := strings.TrimSpace(cfg.UserCollectionID); userCollID != "" {
		return f.fetchUserCollection(ctx, s, libraryID, libraryIDs, userID, profileID, filter, userCollID)
	}

	// Library collection path (existing behaviour).
	if f.CollectionRepo == nil {
		return nil, 0, fmt.Errorf("collection sections require a collection repository")
	}

	if strings.TrimSpace(cfg.LibraryCollectionID) == "" {
		return []*models.MediaItem{}, 0, nil
	}

	if _, err := f.CollectionRepo.GetByID(ctx, cfg.LibraryCollectionID); err != nil {
		return nil, 0, fmt.Errorf("loading library collection: %w", err)
	}

	collectionItems, err := f.CollectionRepo.ListItems(ctx, cfg.LibraryCollectionID)
	if err != nil {
		return nil, 0, fmt.Errorf("listing collection items: %w", err)
	}
	if len(collectionItems) == 0 {
		return []*models.MediaItem{}, 0, nil
	}

	limit := s.ItemLimit
	if limit <= 0 || limit > len(collectionItems) {
		limit = len(collectionItems)
	}

	contentIDs := make([]string, 0, limit)
	for _, item := range collectionItems[:limit] {
		contentIDs = append(contentIDs, item.MediaItemID)
	}

	items, err := f.fetchItemsByContentIDs(ctx, contentIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, 0, err
	}

	itemByID := make(map[string]*models.MediaItem, len(items))
	for _, item := range items {
		itemByID[item.ContentID] = item
	}

	orderedItems := make([]*models.MediaItem, 0, len(contentIDs))
	for _, contentID := range contentIDs {
		item, ok := itemByID[contentID]
		if !ok {
			continue
		}
		orderedItems = append(orderedItems, item)
	}

	return orderedItems, len(orderedItems), nil
}

// fetchUserCollection resolves a personal (profile-scoped) user collection.
// For smart collections it delegates to fetchFiltered; for manual ones it
// fetches the stored item list and looks up the media items by content ID.
func (f *Fetcher) fetchUserCollection(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter, collectionID string) ([]*models.MediaItem, int, error) {
	if f.StoreProvider == nil || userID <= 0 || profileID == "" {
		return []*models.MediaItem{}, 0, nil
	}

	store, err := f.StoreProvider.ForUser(ctx, userID)
	if err != nil {
		return nil, 0, fmt.Errorf("getting user store for collection: %w", err)
	}

	collection, err := store.GetCollection(ctx, collectionID)
	if err != nil {
		return nil, 0, fmt.Errorf("loading user collection: %w", err)
	}

	// Verify the requesting profile can access this collection.
	if collection.ProfileID != profileID && collection.CreatorProfileID != profileID {
		canAccess := false
		for _, allowed := range collection.AllowedProfileIDs {
			if allowed == profileID {
				canAccess = true
				break
			}
		}
		if !canAccess {
			return []*models.MediaItem{}, 0, nil
		}
	}

	// Smart / live-query collection: parse the query definition and use the
	// filtered fetch path, mirroring resolveUserCollectionSource in catalog_resolver.
	isSmartType := strings.EqualFold(strings.TrimSpace(collection.CollectionType), "smart")
	if isSmartType {
		var qd catalog.QueryDefinition
		if err := json.Unmarshal([]byte(collection.QueryDefinition), &qd); err != nil {
			return nil, 0, fmt.Errorf("parsing user collection query_definition: %w", err)
		}
		if strings.TrimSpace(collection.DisplayQueryDefinition) == "" {
			qd = qd.Normalize()
			// Build a synthetic resolved section with the query definition as config.
			cfgBytes, _ := json.Marshal(qd)
			synth := ResolvedSection{
				ID:          s.ID,
				SectionType: SectionCustomFilter,
				Title:       s.Title,
				Featured:    s.Featured,
				ItemLimit:   s.ItemLimit,
				Config:      cfgBytes,
				Position:    s.Position,
			}
			return f.fetchFiltered(ctx, synth, libraryID, libraryIDs, filter)
		}

		qd = applySectionLibraryScopeToQuery(qd.Normalize(), libraryID, libraryIDs)
		qd = catalog.ApplySmartCollectionItemLimit(qd)
		limit := catalog.DefaultSmartCollectionItemLimit
		if qd.Limit != nil && *qd.Limit > 0 {
			limit = *qd.Limit
		}
		executor := &catalog.QueryExecutor{Pool: f.pool}
		items, _, err := executor.Preview(ctx, qd, filter, limit)
		if err != nil {
			return nil, 0, err
		}

		displayAccess := filter
		displayAccess.UserID = userID
		displayAccess.ProfileID = profileID
		items, err = catalog.FilterCollectionItemsByDisplayQuery(ctx, f.pool, items, collection.DisplayQueryDefinition, displayAccess)
		if err != nil {
			return nil, 0, err
		}

		items, total := limitUserCollectionSectionItems(items, s.ItemLimit)
		return items, total, nil
	}

	// Exact collection: fetch stored items.
	collectionItems, err := store.ListCollectionItems(ctx, collectionID)
	if err != nil {
		return nil, 0, fmt.Errorf("listing user collection items: %w", err)
	}
	if len(collectionItems) == 0 {
		return []*models.MediaItem{}, 0, nil
	}

	contentIDs := make([]string, 0, len(collectionItems))
	for _, item := range collectionItems {
		contentIDs = append(contentIDs, item.MediaItemID)
	}

	items, err := f.fetchItemsByContentIDs(ctx, contentIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, 0, err
	}

	itemByID := make(map[string]*models.MediaItem, len(items))
	for _, item := range items {
		itemByID[item.ContentID] = item
	}

	orderedItems := make([]*models.MediaItem, 0, len(contentIDs))
	for _, contentID := range contentIDs {
		item, ok := itemByID[contentID]
		if !ok {
			continue
		}
		orderedItems = append(orderedItems, item)
	}

	displayAccess := filter
	displayAccess.UserID = userID
	displayAccess.ProfileID = profileID
	orderedItems, err = catalog.FilterCollectionItemsByDisplayQuery(ctx, f.pool, orderedItems, collection.DisplayQueryDefinition, displayAccess)
	if err != nil {
		return nil, 0, err
	}

	orderedItems, total := limitUserCollectionSectionItems(orderedItems, s.ItemLimit)

	return orderedItems, total, nil
}

// personalListFetchLimit bounds how many watchlist/favorites entries are
// pulled from the user store when resolving a section; it mirrors the cap the
// catalog resolver uses for personal sources.
const personalListFetchLimit = 10000

// fetchPersonalListSection resolves watchlist and favorites sections from the
// profile's user store, preserving the stored list order and honoring the
// section's optional filter_type / library filters.
func (f *Fetcher) fetchPersonalListSection(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	if f.StoreProvider == nil || userID <= 0 || profileID == "" {
		return []*models.MediaItem{}, 0, nil
	}

	store, err := f.StoreProvider.ForUser(ctx, userID)
	if err != nil {
		return nil, 0, fmt.Errorf("getting user store for %s section: %w", s.SectionType, err)
	}

	var listed []catalog.PersonalListEntry
	switch s.SectionType {
	case SectionWatchlist:
		entries, err := store.ListWatchlist(ctx, profileID, personalListFetchLimit, 0)
		if err != nil {
			return nil, 0, fmt.Errorf("listing watchlist: %w", err)
		}
		entryIDs := make([]string, 0, len(entries))
		for _, entry := range entries {
			entryIDs = append(entryIDs, entry.MediaItemID)
		}
		hidden, err := f.watchlistVisibility.HiddenSeriesIDs(ctx, store, profileID, entryIDs)
		if err != nil {
			return nil, 0, fmt.Errorf("filtering watched watchlist series: %w", err)
		}
		listed = make([]catalog.PersonalListEntry, 0, len(entries))
		for _, entry := range entries {
			if _, ok := hidden[entry.MediaItemID]; ok {
				continue
			}
			listed = append(listed, catalog.PersonalListEntry{ID: entry.MediaItemID, AddedAt: entry.AddedAt})
		}
	case SectionFavorites:
		entries, err := store.ListFavorites(ctx, profileID, personalListFetchLimit, 0)
		if err != nil {
			return nil, 0, fmt.Errorf("listing favorites: %w", err)
		}
		listed = make([]catalog.PersonalListEntry, 0, len(entries))
		for _, entry := range entries {
			listed = append(listed, catalog.PersonalListEntry{ID: entry.MediaItemID, AddedAt: entry.AddedAt})
		}
	default:
		return nil, 0, fmt.Errorf("unsupported personal list section type: %s", s.SectionType)
	}
	if len(listed) == 0 {
		return []*models.MediaItem{}, 0, nil
	}

	// added_at (date added to the list) reorders the entry IDs; the metadata
	// sorts are applied to the resolved items further down.
	qs, hasSort := catalog.NormalizePersonalListSort(parsePersonalListSort(s.Config))
	contentIDs := catalog.OrderPersonalListIDs(listed, qs)

	items, err := f.fetchItemsByContentIDsFiltered(ctx, contentIDs, libraryID, libraryIDs, ParseConfigFilters(s.Config), filter)
	if err != nil {
		return nil, 0, err
	}

	itemByID := make(map[string]*models.MediaItem, len(items))
	for _, item := range items {
		itemByID[item.ContentID] = item
	}
	ordered := make([]*models.MediaItem, 0, len(items))
	for _, contentID := range contentIDs {
		if item, ok := itemByID[contentID]; ok {
			ordered = append(ordered, item)
		}
	}

	if hasSort && qs.Field != "added_at" {
		sortPersonalListItems(ordered, qs)
	}

	ordered, total := limitUserCollectionSectionItems(ordered, s.ItemLimit)
	return ordered, total, nil
}

// parsePersonalListSort extracts the optional flat sort/order keys from a
// watchlist/favorites section config.
func parsePersonalListSort(config json.RawMessage) (string, string) {
	var cfg struct {
		Sort  string `json:"sort"`
		Order string `json:"order"`
	}
	if len(config) > 0 {
		_ = json.Unmarshal(config, &cfg)
	}
	return cfg.Sort, cfg.Order
}

// sortPersonalListItems reorders a personal list rail by the configured sort.
// Items missing the sort field's value go last regardless of direction.
func sortPersonalListItems(items []*models.MediaItem, qs catalog.QuerySort) {
	desc := qs.Order == "desc"
	sort.SliceStable(items, func(i, j int) bool {
		a, b := items[i], items[j]
		switch qs.Field {
		case "title":
			at, bt := personalListTitleKey(a), personalListTitleKey(b)
			if desc {
				return at > bt
			}
			return at < bt
		case "release_date":
			return personalListLess(personalListReleaseKey(a), personalListReleaseKey(b), desc)
		case "year":
			return personalListLess(personalListYearKey(a), personalListYearKey(b), desc)
		case "rating_imdb":
			return personalListLess(personalListRatingKey(a), personalListRatingKey(b), desc)
		default:
			return false
		}
	})
}

func personalListTitleKey(item *models.MediaItem) string {
	if title := strings.TrimSpace(item.SortTitle); title != "" {
		return strings.ToLower(title)
	}
	return strings.ToLower(strings.TrimSpace(item.Title))
}

// personalListReleaseKey returns an ISO date string (lexicographically
// ordered), preferring release_date and falling back to a series' first air
// date. Empty means unknown.
func personalListReleaseKey(item *models.MediaItem) string {
	if item.ReleaseDate != nil && strings.TrimSpace(*item.ReleaseDate) != "" {
		return strings.TrimSpace(*item.ReleaseDate)
	}
	if item.FirstAirDate != nil {
		return strings.TrimSpace(*item.FirstAirDate)
	}
	return ""
}

func personalListYearKey(item *models.MediaItem) string {
	if item.Year <= 0 {
		return ""
	}
	return fmt.Sprintf("%04d", item.Year)
}

func personalListRatingKey(item *models.MediaItem) string {
	if item.RatingIMDB == nil {
		return ""
	}
	return fmt.Sprintf("%08.3f", *item.RatingIMDB)
}

// personalListLess compares string sort keys where "" means the item has no
// value for the field; missing values always sort last.
func personalListLess(a, b string, desc bool) bool {
	if (a == "") != (b == "") {
		return a != ""
	}
	if a == b {
		return false
	}
	if desc {
		return a > b
	}
	return a < b
}

func limitUserCollectionSectionItems(items []*models.MediaItem, limit int) ([]*models.MediaItem, int) {
	total := len(items)
	if limit > 0 && limit < len(items) {
		return items[:limit], total
	}
	return items, total
}

func (f *Fetcher) fetchRecommendationSection(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	if f.RecommendationReader == nil {
		return []*models.MediaItem{}, 0, nil // graceful degradation
	}

	cfg := parseRecommendationSectionConfig(s.Config)
	var scoredItems []recommendations.ScoredItem
	switch s.SectionType {
	case SectionRecommendedForYou:
		row, err := f.RecommendationReader.GetForYouMain(ctx, userID, profileID, s.ItemLimit, filter)
		if err != nil || row == nil {
			return []*models.MediaItem{}, 0, err
		}
		scoredItems = row.Items
	case SectionBecauseYouWatched:
		items, err := f.RecommendationReader.GetBecauseYouWatched(ctx, userID, profileID, cfg.anchor(), s.ItemLimit, filter)
		if err != nil {
			return []*models.MediaItem{}, 0, err
		}
		scoredItems = items
	case SectionSimilarUsersLiked:
		items, err := f.RecommendationReader.GetSimilarUsersLiked(ctx, userID, profileID, s.ItemLimit, filter)
		if err != nil {
			return []*models.MediaItem{}, 0, err
		}
		scoredItems = items
	case SectionTasteMatch:
		// An empty genre is valid: the reader auto-picks the profile's
		// strongest taste cluster (falling back to the server top genre).
		row, err := f.RecommendationReader.GetTasteMatchRow(ctx, userID, profileID, strings.TrimSpace(cfg.Genre), s.ItemLimit, filter)
		if err != nil || row == nil {
			return []*models.MediaItem{}, 0, err
		}
		scoredItems = row.Items
	default:
		return []*models.MediaItem{}, 0, nil
	}

	if len(scoredItems) == 0 {
		return []*models.MediaItem{}, 0, nil
	}

	// Resolve item IDs to full MediaItem objects
	itemIDs := make([]string, len(scoredItems))
	for i, item := range scoredItems {
		itemIDs[i] = item.MediaItemID
	}

	mediaItems, err := f.fetchItemsByContentIDs(ctx, itemIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, 0, err
	}
	orderedItems := orderMediaItems(mediaItems, itemIDs)
	return orderedItems, len(orderedItems), nil
}

func (f *Fetcher) fetchHiddenGems(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.HiddenGemsParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	if p.MinRating == 0 {
		p.MinRating = 7.5
	}

	// Require a valid user/profile to exclude watched items.
	if userID <= 0 || profileID == "" {
		return []*models.MediaItem{}, 0, nil
	}

	repo := catalog.NewDiscoveryRepository(f.pool)
	items, err := repo.ListUnplayedHighRated(ctx, catalog.UnplayedFilter{
		MinRating:  p.MinRating,
		MaxPlays:   p.MaxPlayCount,
		Limit:      s.ItemLimit,
		UserID:     userID,
		ProfileID:  profileID,
		LibraryID:  libraryID,
		LibraryIDs: libraryIDs,
		Filter:     filter,
	})
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

func (f *Fetcher) fetchCriticallyAcclaimed(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.CriticallyAcclaimedParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	if p.MinScore == 0 {
		p.MinScore = 8.0
	}

	repo := catalog.NewDiscoveryRepository(f.pool)
	items, err := repo.ListByRatingThreshold(ctx, catalog.RatingFilter{
		Min:        p.MinScore,
		Limit:      s.ItemLimit,
		LibraryID:  libraryID,
		LibraryIDs: libraryIDs,
		Filter:     filter,
	})
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

func (f *Fetcher) fetchAwardWinners(_ context.Context, s ResolvedSection) ([]*models.MediaItem, int, error) {
	// TODO(awards-data): wire up once award metadata exists
	return []*models.MediaItem{}, 0, nil
}

func (f *Fetcher) fetchForgottenFavorites(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.ForgottenFavoritesParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	if p.LookbackDays <= 0 {
		p.LookbackDays = 365
	}

	// Require a valid user/profile to check watch history.
	if userID <= 0 || profileID == "" {
		return []*models.MediaItem{}, 0, nil
	}

	repo := catalog.NewDiscoveryRepository(f.pool)
	items, err := repo.ListForgottenFavorites(ctx, catalog.ForgottenFavoritesFilter{
		LookbackDays: p.LookbackDays,
		Limit:        s.ItemLimit,
		UserID:       userID,
		ProfileID:    profileID,
		LibraryID:    libraryID,
		LibraryIDs:   libraryIDs,
		Filter:       filter,
	})
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

// fetchFormatShowcase returns items that have at least one media file matching the
// requested stream format.  Filtering is done against media_files columns:
//   - 4k:           resolution IN ('4k','uhd','2160p')
//   - dolby_vision:  EXISTS a video_tracks element with a non-empty dolby_vision field
//   - hdr:           hdr = true
//
// When no format is supplied all items with any of the above formats are returned.
func (f *Fetcher) fetchFormatShowcase(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.FormatShowcaseParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}

	// Build the per-format EXISTS subquery condition against media_files.
	var formatCond string
	switch p.Format {
	case "4k":
		formatCond = `EXISTS (
			SELECT 1 FROM media_files mf
			WHERE (mf.content_id = mi.content_id OR mf.episode_id = mi.content_id)
			  AND mf.missing_since IS NULL
			  AND LOWER(mf.resolution) IN ('4k','uhd','2160p')
		)`
	case "dolby_vision":
		formatCond = `EXISTS (
			SELECT 1 FROM media_files mf
			WHERE (mf.content_id = mi.content_id OR mf.episode_id = mi.content_id)
			  AND mf.missing_since IS NULL
			  AND EXISTS (
				SELECT 1 FROM jsonb_array_elements(COALESCE(mf.video_tracks, '[]'::jsonb)) AS vt
				WHERE vt->>'dolby_vision' IS NOT NULL AND vt->>'dolby_vision' != ''
			  )
		)`
	case "hdr":
		formatCond = `EXISTS (
			SELECT 1 FROM media_files mf
			WHERE (mf.content_id = mi.content_id OR mf.episode_id = mi.content_id)
			  AND mf.missing_since IS NULL
			  AND mf.hdr = true
		)`
	default:
		// No format specified: return items matching any of the above formats.
		formatCond = `EXISTS (
			SELECT 1 FROM media_files mf
			WHERE (mf.content_id = mi.content_id OR mf.episode_id = mi.content_id)
			  AND mf.missing_since IS NULL
			  AND (
				LOWER(mf.resolution) IN ('4k','uhd','2160p')
				OR mf.hdr = true
				OR EXISTS (
					SELECT 1 FROM jsonb_array_elements(COALESCE(mf.video_tracks, '[]'::jsonb)) AS vt
					WHERE vt->>'dolby_vision' IS NOT NULL AND vt->>'dolby_vision' != ''
				)
			  )
		)`
	}

	var conditions []string
	var args []any
	argIdx := 1

	conditions = append(conditions, formatCond)

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	whereClause := "WHERE " + strings.Join(conditions, " AND ")

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	orderBy := "mi.rating_imdb DESC NULLS LAST, mi.content_id ASC"
	if p.Sort == "recent" {
		orderBy = "mi.created_at DESC, mi.content_id ASC"
	}

	query := fmt.Sprintf(
		`SELECT %s FROM %s %s ORDER BY %s LIMIT $%d`,
		itemColumns("mi"), fromClause, whereClause, orderBy, argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching format showcase: %w", err)
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

func (f *Fetcher) fetchAdminCuratedList(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.AdminCuratedListParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	if len(p.ItemIDs) == 0 {
		return []*models.MediaItem{}, 0, nil
	}

	// Build conditions: content_id IN curated set + library scope + access filter.
	var conditions []string
	var args []any
	argIdx := 1

	conditions = append(conditions, fmt.Sprintf("mi.content_id = ANY($%d)", argIdx))
	args = append(args, p.ItemIDs)
	argIdx++

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	whereClause := "WHERE " + strings.Join(conditions, " AND ")

	// Order by position in the curated array. Reuse the item-IDs parameter
	// index (1) for array_position; do NOT pass the slice twice.
	query := fmt.Sprintf(
		`SELECT %s FROM %s %s ORDER BY array_position($1::text[], mi.content_id)`,
		itemColumns("mi"), fromClause, whereClause,
	)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching admin curated list: %w", err)
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

// fetchEditorialSpotlight returns items for an editorial_spotlight section.
// When auto_rotate is true it selects a subject from a candidate list using a
// deterministic ISO-week hash; otherwise it uses the configured subject directly.
func (f *Fetcher) fetchEditorialSpotlight(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	items, total, _, err := f.fetchEditorialSpotlightWithTitle(ctx, s, libraryID, libraryIDs, filter)
	return items, total, err
}

func (f *Fetcher) fetchEditorialSpotlightWithTitle(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, string, error) {
	var p recipes.EditorialSpotlightParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	if p.SubjectType == "" {
		return []*models.MediaItem{}, 0, "", nil
	}

	subject := p.Subject
	if p.AutoRotate {
		cands, err := f.cachedEditorialCandidates(ctx, p.SubjectType, libraryID, libraryIDs, filter, editorialCandidateCacheTTL, f.editorialCandidates)
		if err != nil {
			return nil, 0, "", fmt.Errorf("editorial_spotlight candidates: %w", err)
		}
		if len(cands) == 0 {
			return []*models.MediaItem{}, 0, "", nil
		}
		days := editorialCadenceDays(p.RotationCadence)
		// Build a value-based rotation key. Using `%v` on the *int would print
		// the pointer address, which changes on every process restart and
		// would break the deterministic-rotation contract.
		libKey := "all"
		if libraryID != nil {
			libKey = strconv.Itoa(*libraryID)
		}
		key := fmt.Sprintf("%s|%s", p.SubjectType, libKey)
		idx := recipes.RotationIndex(f.now(), key, len(cands), days)
		subject = cands[idx]
	}

	if subject == "" {
		return []*models.MediaItem{}, 0, "", nil
	}

	// Build a QueryDefinition with the subject filter and run it via the executor.
	def, err := editorialBuildQueryDef(p.SubjectType, subject)
	if err != nil {
		return nil, 0, "", fmt.Errorf("editorial_spotlight build query: %w", err)
	}

	switch {
	case libraryID != nil:
		def.LibraryIDs = []int{*libraryID}
	case libraryIDs != nil:
		if len(def.LibraryIDs) == 0 {
			def.LibraryIDs = append([]int(nil), libraryIDs...)
		} else {
			def.LibraryIDs = intersectLibraryIDs(def.LibraryIDs, libraryIDs)
		}
	}

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}
	def.Limit = &limit

	executor := &catalog.QueryExecutor{Pool: f.pool}
	items, _, _, err := executor.PreviewPage(ctx, def, filter, limit, 0, false)
	if err != nil {
		return nil, 0, "", fmt.Errorf("editorial_spotlight query: %w", err)
	}
	return items, len(items), editorialSpotlightDisplayTitle(s.Title, subject), nil
}

func editorialSpotlightDisplayTitle(baseTitle, subject string) string {
	baseTitle = strings.TrimSpace(baseTitle)
	subject = strings.TrimSpace(subject)
	if subject == "" {
		return baseTitle
	}
	if baseTitle == "" || strings.EqualFold(baseTitle, subject) {
		return subject
	}
	suffix := " - " + subject
	if strings.HasSuffix(baseTitle, suffix) {
		return baseTitle
	}
	return baseTitle + suffix
}

// editorialCadenceDays converts a RotationCadence to a number of days for RotationIndex.
func editorialCadenceDays(c recipes.RotationCadence) int {
	switch c {
	case recipes.CadenceDaily:
		return 1
	case recipes.CadenceMonthly:
		return 30
	default: // weekly or empty
		return 7
	}
}

// editorialBuildQueryDef builds a QueryDefinition for the given subject type and subject value.
func editorialBuildQueryDef(subjectType, subject string) (catalog.QueryDefinition, error) {
	var rule catalog.QueryRule
	switch subjectType {
	case "director":
		rule = catalog.QueryRule{Field: "director", Op: "is", Value: subject}
	case "actor":
		rule = catalog.QueryRule{Field: "actor", Op: "is", Value: subject}
	case "studio":
		rule = catalog.QueryRule{Field: "studio", Op: "is", Value: subject}
	case "era":
		startYear, endYear, err := eraToYearRange(subject)
		if err != nil {
			return catalog.QueryDefinition{}, err
		}
		// release_date between uses string dates ("YYYY-01-01", "YYYY-12-31").
		startISO := fmt.Sprintf("%d-01-01", startYear)
		endISO := fmt.Sprintf("%d-12-31", endYear)
		rule = catalog.QueryRule{Field: "release_date", Op: "between", Value: []any{startISO, endISO}}
	default:
		return catalog.QueryDefinition{}, fmt.Errorf("editorial_spotlight: unsupported subject_type %q", subjectType)
	}

	def := catalog.QueryDefinition{
		Match: "all",
		Groups: []catalog.QueryGroup{
			{Match: "all", Rules: []catalog.QueryRule{rule}},
		},
	}
	return def.Normalize(), nil
}

// eraToYearRange converts an era label like "1980s" to its start and end years.
func eraToYearRange(era string) (int, int, error) {
	switch era {
	case "1970s":
		return 1970, 1979, nil
	case "1980s":
		return 1980, 1989, nil
	case "1990s":
		return 1990, 1999, nil
	case "2000s":
		return 2000, 2009, nil
	case "2010s":
		return 2010, 2019, nil
	case "2020s":
		return 2020, 2029, nil
	default:
		return 0, 0, fmt.Errorf("editorial_spotlight: unknown era %q", era)
	}
}

// editorialCandidates returns the top subject names for auto-rotation, applying
// library scope and access filter so results are scoped to the user's libraries.
func (f *Fetcher) editorialCandidates(ctx context.Context, subjectType string, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]string, error) {
	switch subjectType {
	case "director":
		return f.topPersonCandidates(ctx, 2 /* PersonKindDirector */, libraryID, libraryIDs, filter)
	case "actor":
		return f.topPersonCandidates(ctx, 1 /* PersonKindActor */, libraryID, libraryIDs, filter)
	case "studio":
		return f.topStudioCandidates(ctx, libraryID, libraryIDs, filter)
	case "era":
		// Auto-rotate excludes the current decade — incomplete data + stylistic skew.
		// "2020s" is still accepted as a manually-pinned subject via eraToYearRange.
		return []string{"1970s", "1980s", "1990s", "2000s", "2010s"}, nil
	default:
		return nil, fmt.Errorf("editorial_spotlight: unsupported subject_type %q", subjectType)
	}
}

const editorialCandidateLimit = 50

// topPersonCandidates returns the top N person names by item count for the given kind.
func (f *Fetcher) topPersonCandidates(ctx context.Context, kind int, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]string, error) {
	var conditions []string
	var args []any
	argIdx := 1

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	whereClause := "WHERE 1=1"
	if len(conditions) > 0 {
		whereClause += " AND " + strings.Join(conditions, " AND ")
	}

	args = append(args, kind, editorialCandidateLimit)
	// Weighted billing: SUM(1/(sort_order+1)) favors top-billed credits
	// (TMDB convention: 0 = lead). HAVING MIN(sort_order) <= 5 excludes
	// people who only ever appear in deep supporting roles.
	query := fmt.Sprintf(`
		SELECT p.name
		FROM people p
		JOIN item_people ip ON ip.person_id = p.id AND ip.kind = $%d
		JOIN %s ON mi.content_id = ip.content_id
		%s
		GROUP BY p.name
		HAVING MIN(ip.sort_order) <= 5
		ORDER BY SUM(1.0 / (ip.sort_order + 1)) DESC, COUNT(*) DESC
		LIMIT $%d
	`, argIdx, fromClause, whereClause, argIdx+1)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("querying top persons (kind=%d): %w", kind, err)
	}
	defer rows.Close()

	var names []string
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			return nil, fmt.Errorf("scanning person name: %w", err)
		}
		names = append(names, name)
	}
	return names, rows.Err()
}

// topStudioCandidates returns the top N studio names by item count.
func (f *Fetcher) topStudioCandidates(ctx context.Context, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]string, error) {
	var conditions []string
	var args []any
	argIdx := 1

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	whereClause := ""
	if len(conditions) > 0 {
		whereClause = "AND " + strings.Join(conditions, " AND ")
	}

	args = append(args, editorialCandidateLimit)
	query := fmt.Sprintf(`
		SELECT studio
		FROM (
			SELECT unnest(mi.studios) AS studio
			FROM %s
			WHERE mi.studios IS NOT NULL
			%s
		) sub
		GROUP BY studio
		ORDER BY COUNT(*) DESC
		LIMIT $%d
	`, fromClause, whereClause, argIdx)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("querying top studios: %w", err)
	}
	defer rows.Close()

	var studios []string
	for rows.Next() {
		var studio string
		if err := rows.Scan(&studio); err != nil {
			return nil, fmt.Errorf("scanning studio name: %w", err)
		}
		studios = append(studios, studio)
	}
	return studios, rows.Err()
}

type recommendationSectionConfig struct {
	// SourceItemID is the historical key for the because_you_watched anchor;
	// AnchorItemID is the name the recipe params and web UI use. Both are
	// honored so sections saved through either surface pin correctly.
	SourceItemID string `json:"source_item_id"`
	AnchorItemID string `json:"anchor_item_id"`
	Genre        string `json:"genre"`
}

// anchor returns the pinned because_you_watched anchor item, preferring the
// legacy key when both are present. Empty means auto-pick.
func (c recommendationSectionConfig) anchor() string {
	if strings.TrimSpace(c.SourceItemID) != "" {
		return strings.TrimSpace(c.SourceItemID)
	}
	return strings.TrimSpace(c.AnchorItemID)
}

func parseRecommendationSectionConfig(config json.RawMessage) recommendationSectionConfig {
	var cfg recommendationSectionConfig
	if len(config) == 0 {
		return cfg
	}
	_ = json.Unmarshal(config, &cfg)
	return cfg
}

func orderMediaItems(items []*models.MediaItem, orderedIDs []string) []*models.MediaItem {
	if len(items) <= 1 {
		return items
	}
	byID := make(map[string]*models.MediaItem, len(items))
	for _, item := range items {
		byID[item.ContentID] = item
	}
	ordered := make([]*models.MediaItem, 0, len(items))
	for _, id := range orderedIDs {
		item, ok := byID[id]
		if !ok {
			continue
		}
		ordered = append(ordered, item)
	}
	return ordered
}

func (f *Fetcher) fetchRecentlyAdded(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	query, args := buildRecentlyAddedQuery(s, libraryID, libraryIDs, filter)
	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	return items, len(items), err
}

type sectionQuery struct {
	sql  string
	args []any
}

func buildRecentlyAddedQuery(s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) (string, []any) {
	cfgFilters := ParseConfigFilters(s.Config)

	// Backwards compat: support legacy "types" config field
	var legacyCfg struct {
		Types []string `json:"types"`
	}
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &legacyCfg)
	}
	if cfgFilters.FilterType == "" && len(legacyCfg.Types) > 0 {
		cfgFilters.FilterType = legacyCfg.Types[0]
	}

	if query, ok := buildRecentlyAddedSingleLibraryQuery(s, cfgFilters, libraryID, libraryIDs, filter); ok {
		return query.sql, query.args
	}

	var conditions []string
	var args []any
	argIdx := 1

	applyConfigTypeFilter("mi", cfgFilters.FilterType, &conditions, &args, &argIdx)

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, cfgFilters.LibraryIDs(), filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	whereClause := ""
	if len(conditions) > 0 {
		whereClause = "WHERE " + strings.Join(conditions, " AND ")
	}

	query := fmt.Sprintf(
		`SELECT %s FROM %s %s ORDER BY mi.created_at DESC, mi.content_id ASC LIMIT $%d`,
		itemColumnsLatestMangaPoster("mi"), fromClause, whereClause, argIdx,
	)
	args = append(args, s.ItemLimit)
	return query, args
}

func buildRecentlyAddedSingleLibraryQuery(s ResolvedSection, cfgFilters SectionConfigFilters, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) (sectionQuery, bool) {
	configLibraryIDs := cfgFilters.LibraryIDs()
	var singleLibraryID int
	switch {
	case libraryID != nil:
		singleLibraryID = *libraryID
	case len(configLibraryIDs) == 1:
		singleLibraryID = configLibraryIDs[0]
	default:
		return sectionQuery{}, false
	}
	if singleLibraryID <= 0 {
		return sectionQuery{}, false
	}

	var conditions []string
	var args []any
	argIdx := 1

	conditions = append(conditions, fmt.Sprintf("mil.media_folder_id = $%d", argIdx))
	args = append(args, singleLibraryID)
	argIdx++

	if libraryIDs != nil {
		if len(libraryIDs) == 0 {
			conditions = append(conditions, "1 = 0")
		} else {
			placeholders := make([]string, len(libraryIDs))
			for i, id := range libraryIDs {
				placeholders[i] = fmt.Sprintf("$%d", argIdx)
				args = append(args, id)
				argIdx++
			}
			conditions = append(conditions, fmt.Sprintf("mil.media_folder_id IN (%s)", strings.Join(placeholders, ", ")))
		}
	}

	if len(filter.DisabledLibraryIDs) > 0 {
		placeholders := make([]string, len(filter.DisabledLibraryIDs))
		for i, id := range filter.DisabledLibraryIDs {
			placeholders[i] = fmt.Sprintf("$%d", argIdx)
			args = append(args, id)
			argIdx++
		}
		conditions = append(conditions, fmt.Sprintf("mil.media_folder_id NOT IN (%s)", strings.Join(placeholders, ", ")))
	}

	applyConfigTypeFilter("mi", cfgFilters.FilterType, &conditions, &args, &argIdx)
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	whereClause := "WHERE " + strings.Join(conditions, " AND ")
	query := fmt.Sprintf(
		`SELECT %s FROM media_item_libraries mil JOIN media_items mi ON mi.content_id = mil.content_id %s ORDER BY mil.first_seen_at DESC, mil.content_id ASC LIMIT $%d`,
		itemColumnsLatestMangaPoster("mi"), whereClause, argIdx,
	)
	args = append(args, s.ItemLimit)
	return sectionQuery{sql: query, args: args}, true
}

func buildRecentlyReleasedQuery(s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) (string, []any) {
	cfgFilters := ParseConfigFilters(s.Config)

	var conditions []string
	var args []any
	argIdx := 1

	applyConfigTypeFilter("mi", cfgFilters.FilterType, &conditions, &args, &argIdx)

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, cfgFilters.LibraryIDs(), filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	whereClause := ""
	if len(conditions) > 0 {
		whereClause = "WHERE " + strings.Join(conditions, " AND ")
	}

	query := fmt.Sprintf(
		`SELECT %s FROM %s %s ORDER BY mi.year DESC, mi.created_at DESC LIMIT $%d`,
		itemColumnsLatestMangaPoster("mi"), fromClause, whereClause, argIdx,
	)
	args = append(args, s.ItemLimit)
	return query, args
}

func (f *Fetcher) fetchRecentlyReleased(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	query, args := buildRecentlyReleasedQuery(s, libraryID, libraryIDs, filter)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	return items, len(items), err
}

func (f *Fetcher) fetchFiltered(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	def, err := ParseQueryDefinition(s.Config)
	if err != nil {
		return nil, 0, fmt.Errorf("parsing query definition: %w", err)
	}

	def = applySectionLibraryScopeToQuery(def, libraryID, libraryIDs)

	if s.ItemLimit > 0 {
		limit := s.ItemLimit
		def.Limit = &limit
	}

	executor := &catalog.QueryExecutor{Pool: f.pool}
	items, _, hasMore, err := executor.PreviewPage(ctx, def, filter, s.ItemLimit, 0, false)
	if err != nil {
		return nil, 0, err
	}

	total := len(items)
	if hasMore && s.ItemLimit > 0 && total <= s.ItemLimit {
		total = s.ItemLimit + 1
	}

	return items, total, nil
}

func applySectionLibraryScopeToQuery(def catalog.QueryDefinition, libraryID *int, libraryIDs []int) catalog.QueryDefinition {
	switch {
	case libraryID != nil:
		def.LibraryIDs = []int{*libraryID}
	case libraryIDs != nil:
		if len(def.LibraryIDs) == 0 {
			def.LibraryIDs = append([]int(nil), libraryIDs...)
		} else {
			def.LibraryIDs = intersectLibraryIDs(def.LibraryIDs, libraryIDs)
		}
	}
	return def
}

func buildRandomQuery(s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) (string, []any, int) {
	cfgFilters := ParseConfigFilters(s.Config)

	var conditions []string
	var args []any
	argIdx := 1

	applyConfigTypeFilter("mi", cfgFilters.FilterType, &conditions, &args, &argIdx)

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, cfgFilters.LibraryIDs(), filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	whereClause := ""
	if len(conditions) > 0 {
		whereClause = "WHERE " + strings.Join(conditions, " AND ")
	}

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}
	queryLimit := limit + 1

	query := fmt.Sprintf(
		`SELECT candidate.content_id
		FROM (
			SELECT DISTINCT mi.content_id
			FROM %s
			%s
		) candidate
		ORDER BY RANDOM()
		LIMIT $%d`,
		fromClause, whereClause, argIdx,
	)
	args = append(args, queryLimit)
	return query, args, limit
}

func (f *Fetcher) fetchRandom(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	query, args, limit := buildRandomQuery(s, libraryID, libraryIDs, filter)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var contentIDs []string
	for rows.Next() {
		var contentID string
		if err := rows.Scan(&contentID); err != nil {
			return nil, 0, fmt.Errorf("scanning random section content id: %w", err)
		}
		contentIDs = append(contentIDs, contentID)
	}
	if err := rows.Err(); err != nil {
		return nil, 0, err
	}

	hasMore := len(contentIDs) > limit
	if hasMore {
		contentIDs = contentIDs[:limit]
	}

	items, err := f.fetchItemsByContentIDs(ctx, contentIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, 0, err
	}

	ordered := orderMediaItems(items, contentIDs)
	total := len(ordered)
	if hasMore && total <= limit {
		total = limit + 1
	}

	return ordered, total, nil
}

func (f *Fetcher) fetchItemsByContentIDs(ctx context.Context, contentIDs []string, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, error) {
	return f.fetchItemsByContentIDsFiltered(ctx, contentIDs, libraryID, libraryIDs, SectionConfigFilters{}, filter)
}

// fetchItemsByContentIDsFiltered is fetchItemsByContentIDs with the section
// config's optional type and library filters applied on top of the access
// scope.
func (f *Fetcher) fetchItemsByContentIDsFiltered(ctx context.Context, contentIDs []string, libraryID *int, libraryIDs []int, cfgFilters SectionConfigFilters, filter catalog.AccessFilter) ([]*models.MediaItem, error) {
	if len(contentIDs) == 0 {
		return []*models.MediaItem{}, nil
	}

	var conditions []string
	var args []any
	argIdx := 1

	placeholders := make([]string, len(contentIDs))
	for i, contentID := range contentIDs {
		placeholders[i] = fmt.Sprintf("$%d", argIdx)
		args = append(args, contentID)
		argIdx++
	}
	conditions = append(conditions, fmt.Sprintf("mi.content_id IN (%s)", strings.Join(placeholders, ", ")))

	applyConfigTypeFilter("mi", cfgFilters.FilterType, &conditions, &args, &argIdx)

	effectiveLibraryIDs := effectiveFetchLibraryIDs(libraryIDs, filter)
	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, effectiveLibraryIDs, cfgFilters.LibraryIDs(), filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	query := fmt.Sprintf(
		`SELECT %s FROM %s WHERE %s`,
		itemColumns("mi"), fromClause, strings.Join(conditions, " AND "),
	)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	return scanMediaItems(rows)
}

func (f *Fetcher) fetchEpisodeTargetsByContentIDs(ctx context.Context, contentIDs []string, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, map[string]SectionItemMeta, error) {
	if len(contentIDs) == 0 {
		return []*models.MediaItem{}, map[string]SectionItemMeta{}, nil
	}

	var conditions []string
	var args []any
	argIdx := 1

	placeholders := make([]string, len(contentIDs))
	for i, contentID := range contentIDs {
		placeholders[i] = fmt.Sprintf("$%d", argIdx)
		args = append(args, contentID)
		argIdx++
	}
	conditions = append(conditions, fmt.Sprintf("e.content_id IN (%s)", strings.Join(placeholders, ", ")))

	effectiveLibraryIDs := effectiveFetchLibraryIDs(libraryIDs, filter)

	fromClause := "episodes e JOIN media_items si ON e.series_id = si.content_id LEFT JOIN seasons s ON s.content_id = e.season_id"
	if libraryID != nil || effectiveLibraryIDs != nil {
		fromClause += " JOIN media_item_libraries mil ON si.content_id = mil.content_id"
	}

	if libraryID != nil {
		conditions = append(conditions, fmt.Sprintf("mil.media_folder_id = $%d", argIdx))
		args = append(args, *libraryID)
		argIdx++
	}

	if effectiveLibraryIDs != nil {
		if len(effectiveLibraryIDs) == 0 {
			return []*models.MediaItem{}, map[string]SectionItemMeta{}, nil
		}
		placeholders = make([]string, len(effectiveLibraryIDs))
		for i, id := range effectiveLibraryIDs {
			placeholders[i] = fmt.Sprintf("$%d", argIdx)
			args = append(args, id)
			argIdx++
		}
		conditions = append(conditions, fmt.Sprintf("mil.media_folder_id IN (%s)", strings.Join(placeholders, ", ")))
	}

	catalog.ApplySectionAccessFilter("si", filter, &conditions, &args, &argIdx)

	query := fmt.Sprintf(`
		SELECT
			e.content_id,
			e.series_id,
			e.title,
			e.overview,
			e.runtime,
			e.rating_imdb,
			COALESCE(NULLIF(s.poster_path, ''), NULLIF(si.poster_path, ''), NULLIF(e.still_path, ''), '') AS poster_path,
			COALESCE(NULLIF(s.poster_thumbhash, ''), NULLIF(si.poster_thumbhash, ''), NULLIF(e.still_thumbhash, ''), '') AS poster_thumbhash,
			e.season_number,
			e.episode_number,
			e.air_date,
			si.title,
			si.genres,
			si.content_rating,
			COALESCE(NULLIF(e.still_path, ''), NULLIF(si.backdrop_path, ''), '') AS backdrop_path,
			COALESCE(NULLIF(e.still_thumbhash, ''), NULLIF(si.backdrop_thumbhash, ''), '') AS backdrop_thumbhash,
			si.logo_path,
			si.status
		FROM %s
		WHERE %s
	`, fromClause, strings.Join(conditions, " AND "))

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, nil, err
	}
	defer rows.Close()

	items := []*models.MediaItem{}
	itemMeta := map[string]SectionItemMeta{}
	for rows.Next() {
		var (
			item          models.MediaItem
			seriesID      string
			seasonNumber  int
			episodeNumber int
			seriesTitle   string
			airDate       *time.Time
		)
		item.Type = "episode"
		err := rows.Scan(
			&item.ContentID,
			&seriesID,
			&item.Title,
			&item.Overview,
			&item.Runtime,
			&item.RatingIMDB,
			&item.PosterPath,
			&item.PosterThumbhash,
			&seasonNumber,
			&episodeNumber,
			&airDate,
			&seriesTitle,
			&item.Genres,
			&item.ContentRating,
			&item.BackdropPath,
			&item.BackdropThumbhash,
			&item.LogoPath,
			&item.Status,
		)
		if err != nil {
			return nil, nil, fmt.Errorf("scanning episode section item: %w", err)
		}
		items = append(items, &item)
		itemMeta[item.ContentID] = SectionItemMeta{
			SeriesID:      &seriesID,
			SeriesTitle:   seriesTitle,
			SeasonNumber:  &seasonNumber,
			EpisodeNumber: &episodeNumber,
			Badges:        recentSeasonPremiereBadges(seasonNumber, episodeNumber, airDate),
		}
	}
	if err := rows.Err(); err != nil {
		return nil, nil, err
	}

	return items, itemMeta, nil
}

func effectiveFetchLibraryIDs(libraryIDs []int, filter catalog.AccessFilter) []int {
	if libraryIDs != nil {
		return libraryIDs
	}
	if filter.AllowedLibraryIDs != nil {
		return filter.AllowedLibraryIDs
	}
	return nil
}

func recentSeasonPremiereBadges(seasonNumber, episodeNumber int, airDate *time.Time) []string {
	if seasonNumber <= 1 || episodeNumber != 1 || airDate == nil {
		return nil
	}

	nowDate := utcDay(time.Now().UTC())
	premiereDate := utcDay(airDate.UTC())
	windowStart := nowDate.AddDate(0, 0, -(recentSeasonPremiereBadgeWindowDays - 1))
	if premiereDate.Before(windowStart) || premiereDate.After(nowDate) {
		return nil
	}

	return []string{"season_premiere"}
}

func utcDay(t time.Time) time.Time {
	return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, time.UTC)
}

// itemColumnsList returns the alias-prefixed SELECT columns matching
// scanMediaItems, in scan order. Mirrors catalog.browseItemColumns. The shared
// source of truth for itemColumns and its manga-poster-override variant.
func itemColumnsList(alias string) []string {
	cols := []string{
		"content_id", "type", "title", "sort_title", "original_title", "year", "genres",
		"content_rating", "runtime", "overview", "tagline",
		"rating_imdb", "rating_tmdb", "rating_rt_critic", "rating_rt_audience",
		"imdb_id", "tmdb_id", "tvdb_id",
		"poster_path", "poster_thumbhash", "backdrop_path", "backdrop_thumbhash", "logo_path",
		"metadata_s3_path", "metadata_etag", "season_count",
		"studios", "networks", "countries", "release_date::text", "first_air_date", "last_air_date",
		"show_status",
		"matched_at", "status", "created_at", "updated_at",
	}
	prefixed := make([]string, len(cols))
	for i, c := range cols {
		prefixed[i] = alias + "." + c
	}
	return prefixed
}

// itemColumns returns the SELECT column list matching scanMediaItems.
// Mirrors catalog.browseItemColumns.
func itemColumns(alias string) string {
	return strings.Join(itemColumnsList(alias), ", ")
}

// itemColumnsLatestMangaPoster returns the same SELECT column list as
// itemColumns (identical order and aliases, so scanMediaItems is unchanged) but
// overrides poster_path/poster_thumbhash for type='manga' SERIES rows: a manga
// series card shows the cover of its latest-added volume/chapter (the linked
// manga_chapters row with the greatest created_at) instead of the AniList series
// cover, falling back to the series' own poster when no chapter cover exists.
//
// Strictly gated on mi.type = 'manga' so movies/TV/audiobooks/ebooks keep their
// own poster exactly. Used only by the recently-added / recently-released
// section builders; all other queries keep itemColumns.
func itemColumnsLatestMangaPoster(alias string) string {
	cols := itemColumnsList(alias)
	for i, c := range cols {
		switch c {
		case alias + ".poster_path":
			cols[i] = mangaLatestVolumePosterExpr(alias, "poster_path")
		case alias + ".poster_thumbhash":
			cols[i] = mangaLatestVolumePosterExpr(alias, "poster_thumbhash")
		}
	}
	return strings.Join(cols, ", ")
}

// mangaLatestVolumePosterExpr emits the manga-gated CASE override for a single
// poster column, aliased back to the original column name so the scan order and
// column set are unchanged.
func mangaLatestVolumePosterExpr(alias, col string) string {
	// NULLIF(...,'') on each operand: poster columns default to '' (empty
	// string), not NULL, so a plain COALESCE would surface a cover-less latest
	// chapter's empty poster instead of falling back to the series' own cover.
	// Mirrors the episode poster expressions above; trailing '' keeps the THEN
	// branch non-NULL.
	return "CASE WHEN " + alias + ".type = 'manga' THEN COALESCE(NULLIF((" +
		"SELECT c." + col + " FROM media_items c " +
		"JOIN manga_chapters mc ON mc.chapter_content_id = c.content_id " +
		"WHERE mc.series_content_id = " + alias + ".content_id " +
		"ORDER BY c.created_at DESC, c.content_id DESC LIMIT 1), ''), " +
		"NULLIF(" + alias + "." + col + ", ''), '') ELSE " + alias + "." + col + " END AS " + col
}

// scanMediaItems scans rows into MediaItem slices. Must match itemColumns order.
func scanMediaItems(rows pgx.Rows) ([]*models.MediaItem, error) {
	var items []*models.MediaItem
	for rows.Next() {
		var item models.MediaItem
		err := rows.Scan(
			&item.ContentID, &item.Type, &item.Title, &item.SortTitle, &item.OriginalTitle,
			&item.Year, &item.Genres, &item.ContentRating, &item.Runtime, &item.Overview, &item.Tagline,
			&item.RatingIMDB, &item.RatingTMDB, &item.RatingRTCritic, &item.RatingRTAudience,
			&item.ImdbID, &item.TmdbID, &item.TvdbID,
			&item.PosterPath, &item.PosterThumbhash, &item.BackdropPath, &item.BackdropThumbhash, &item.LogoPath,
			&item.MetadataS3Path, &item.MetadataEtag, &item.SeasonCount,
			&item.Studios, &item.Networks, &item.Countries, &item.ReleaseDate, &item.FirstAirDate, &item.LastAirDate,
			&item.ShowStatus,
			&item.MatchedAt, &item.Status, &item.CreatedAt, &item.UpdatedAt,
		)
		if err != nil {
			return nil, fmt.Errorf("scanning item: %w", err)
		}
		items = append(items, &item)
	}
	return items, rows.Err()
}

// trendingDiscoverEntry is a provider-agnostic external trending result.
type trendingDiscoverEntry struct {
	tmdbID    string
	imdbID    string
	tvdbID    string
	mediaType string // "movie" | "tv"
}

// newTrendingEntry normalizes a provider entry into a trendingDiscoverEntry,
// stringifying the numeric external IDs and dropping any that are unset (<= 0).
func newTrendingEntry(tmdbID, tvdbID int, imdbID, mediaType string) trendingDiscoverEntry {
	e := trendingDiscoverEntry{imdbID: imdbID, mediaType: mediaType}
	if tmdbID > 0 {
		e.tmdbID = strconv.Itoa(tmdbID)
	}
	if tvdbID > 0 {
		e.tvdbID = strconv.Itoa(tvdbID)
	}
	return e
}

// fetchTrendingDiscover surfaces external global trending (TMDB or Trakt),
// mixing movies + series, matched to titles in the viewer's enabled libraries.
// The external fetch + ID resolution are cached briefly so it does not hit the
// upstream API on every home-page load.
func (f *Fetcher) fetchTrendingDiscover(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.TrendingDiscoverParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	source, window := canonicalTrendingKey(p.Source, p.Window)

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	orderedIDs, err := f.loadTrendingDiscoverContentIDs(ctx, source, window)
	if err != nil {
		return nil, 0, err
	}
	if len(orderedIDs) == 0 {
		return []*models.MediaItem{}, 0, nil
	}

	items, err := f.fetchItemsByContentIDs(ctx, orderedIDs, libraryID, libraryIDs, filter)
	if err != nil {
		return nil, 0, err
	}

	// Re-order to trending rank (fetchItemsByContentIDs returns DB order) and
	// truncate to the section's display limit.
	ordered := orderMediaItems(items, orderedIDs)
	if len(ordered) > limit {
		ordered = ordered[:limit]
	}
	return ordered, len(ordered), nil
}

// loadTrendingDiscoverContentIDs returns the persisted, catalog-resolved content
// IDs for the canonical (source, window). It reads only the snapshot table; the
// upstream fetch happens out-of-band in TrendingRefresher. Returns nil when no
// snapshot reader is configured or no snapshot exists yet.
func (f *Fetcher) loadTrendingDiscoverContentIDs(ctx context.Context, source, window string) ([]string, error) {
	if f.TrendingSnapshots == nil {
		return nil, nil
	}
	snap, found, err := f.TrendingSnapshots.Get(ctx, source, window)
	if err != nil {
		return nil, err
	}
	if !found {
		return nil, nil
	}
	return snap.ContentIDs, nil
}

// orderedTrendingContentIDs maps trending entries to library content IDs in
// trending order, preferring TVDB (series) > TMDB > IMDb, de-duplicated.
func orderedTrendingContentIDs(entries []trendingDiscoverEntry, movieLookup, seriesLookup *catalog.ExternalIDLookup) []string {
	seen := make(map[string]struct{}, len(entries))
	out := make([]string, 0, len(entries))
	for _, e := range entries {
		// Only movies and series are resolvable; skip anything else (TMDB
		// trending/all also returns media_type "person").
		var lookup *catalog.ExternalIDLookup
		isSeries := e.mediaType == "tv"
		switch e.mediaType {
		case "movie":
			lookup = movieLookup
		case "tv":
			lookup = seriesLookup
		default:
			continue
		}
		if lookup == nil {
			continue
		}
		var id string
		if isSeries && e.tvdbID != "" {
			id = lookup.ByTVDB[e.tvdbID]
		}
		if id == "" && e.tmdbID != "" {
			id = lookup.ByTMDB[e.tmdbID]
		}
		if id == "" && e.imdbID != "" {
			id = lookup.ByIMDb[e.imdbID]
		}
		if id == "" {
			continue
		}
		if _, dup := seen[id]; dup {
			continue
		}
		seen[id] = struct{}{}
		out = append(out, id)
	}
	return out
}

func (f *Fetcher) fetchTrending(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.TrendingParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	interval := "7 days"
	switch p.Window {
	case "24h":
		interval = "24 hours"
	case "7d", "":
		interval = "7 days"
	case "30d":
		interval = "30 days"
	}

	var conditions []string
	var args []any
	argIdx := 1

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	conditions = append(conditions, fmt.Sprintf("uwh.watched_at > NOW() - $%d::interval", argIdx))
	args = append(args, interval)
	argIdx++

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	whereClause := "WHERE " + strings.Join(conditions, " AND ")

	query := fmt.Sprintf(
		`SELECT %s FROM %s JOIN user_watch_history uwh ON uwh.media_item_id = mi.content_id %s GROUP BY mi.content_id ORDER BY COUNT(DISTINCT uwh.profile_id) DESC, COUNT(*) DESC LIMIT $%d`,
		itemColumns("mi"), fromClause, whereClause, argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching trending: %w", err)
	}
	defer rows.Close()
	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

func (f *Fetcher) fetchProfileActivityFeed(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.ProfileActivityFeedParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	target := p.ProfileID

	// Household mode (target == "") leaks all history when caller is unauthenticated.
	if target == "" && profileID == "" {
		return []*models.MediaItem{}, 0, nil
	}

	var args []any
	argIdx := 1

	// CTE deduplicates per media_item_id and keeps the most-recent watched_at,
	// so each item appears once and is ordered by latest-watch DESC.
	var cteCond string
	var cteWindow string
	if target == "" {
		cteCond = fmt.Sprintf("profile_id <> $%d", argIdx)
		args = append(args, profileID)
		argIdx++
		cteWindow = "INTERVAL '7 days'"
	} else {
		cteCond = fmt.Sprintf("profile_id = $%d", argIdx)
		args = append(args, target)
		argIdx++
		cteWindow = "INTERVAL '30 days'"
	}

	var conditions []string
	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	whereClause := ""
	if len(conditions) > 0 {
		whereClause = "WHERE " + strings.Join(conditions, " AND ")
	}

	query := fmt.Sprintf(
		`WITH most_recent AS (
			SELECT media_item_id, MAX(watched_at) AS latest
			FROM user_watch_history
			WHERE %s AND watched_at > NOW() - %s
			GROUP BY media_item_id
		)
		SELECT %s
		FROM %s
		JOIN most_recent mr ON mr.media_item_id = mi.content_id
		%s
		ORDER BY mr.latest DESC
		LIMIT $%d`,
		cteCond, cteWindow,
		itemColumns("mi"), fromClause, whereClause, argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching profile activity feed: %w", err)
	}
	defer rows.Close()
	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

func (f *Fetcher) fetchNewToLibrary(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.NewToLibraryParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	days := p.LookbackDays
	if days <= 0 {
		days = 30
	}

	var conditions []string
	var args []any
	argIdx := 1

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	conditions = append(conditions, fmt.Sprintf("mi.created_at > NOW() - ($%d || ' days')::interval", argIdx))
	args = append(args, days)
	argIdx++

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	whereClause := "WHERE " + strings.Join(conditions, " AND ")

	query := fmt.Sprintf(
		`SELECT %s FROM %s %s ORDER BY mi.created_at DESC LIMIT $%d`,
		itemColumns("mi"), fromClause, whereClause, argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching new to library: %w", err)
	}
	defer rows.Close()
	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

func (f *Fetcher) fetchMostWatched(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.MostWatchedParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	interval := "7 days"
	if p.Window == "month" {
		interval = "30 days"
	}

	var conditions []string
	var args []any
	argIdx := 1

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	conditions = append(conditions, fmt.Sprintf("uwh.watched_at > NOW() - $%d::interval", argIdx))
	args = append(args, interval)
	argIdx++

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	whereClause := "WHERE " + strings.Join(conditions, " AND ")

	query := fmt.Sprintf(
		`SELECT %s FROM %s JOIN user_watch_history uwh ON uwh.media_item_id = mi.content_id %s GROUP BY mi.content_id ORDER BY COUNT(*) DESC LIMIT $%d`,
		itemColumns("mi"), fromClause, whereClause, argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching most watched: %w", err)
	}
	defer rows.Close()
	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

// buildLibraryScope returns the FROM clause and membership predicates that
// constrain a section query to the requested library scope. Membership is
// checked with EXISTS / NOT EXISTS semi-joins rather than a row join: an item
// present in several in-scope libraries must produce exactly ONE result row
// (rails without a GROUP BY would otherwise return duplicates that eat limit
// slots), and the deny check must be item-level — with a row join, an item
// linked to both an allowed and a disabled library passes via the allowed
// membership row (see catalog audit 2026-05-01 §3 Pattern D, the same reason
// catalog's buildLibraryScopeJoin uses semi-joins).
func buildLibraryScope(libraryID *int, libraryIDs []int, configLibraryIDs []int, disabledLibraryIDs []int, argIdx int) (string, []string, []any, int) {
	fromClause := "media_items mi"
	var conditions []string
	var args []any

	memberOfAny := func(ids []int) {
		conditions = append(conditions, fmt.Sprintf(
			"EXISTS (SELECT 1 FROM media_item_libraries mil_scope_in WHERE mil_scope_in.content_id = mi.content_id AND mil_scope_in.media_folder_id = ANY($%d))",
			argIdx,
		))
		args = append(args, append([]int(nil), ids...))
		argIdx++
	}

	if libraryID != nil {
		memberOfAny([]int{*libraryID})
	}

	if len(configLibraryIDs) > 0 && libraryID == nil {
		memberOfAny(configLibraryIDs)
	}

	if libraryIDs != nil {
		if len(libraryIDs) == 0 {
			conditions = append(conditions, "1 = 0")
			return fromClause, conditions, args, argIdx
		}
		memberOfAny(libraryIDs)
	}

	if len(disabledLibraryIDs) > 0 {
		if libraryID == nil && libraryIDs == nil && len(configLibraryIDs) == 0 {
			// Deny-only mode: still require at least one library membership so
			// stale or provisional media_items rows with no membership don't
			// become visible through a vacuous NOT EXISTS (mirrors
			// appendDiscoveryLibraryScope in package catalog).
			conditions = append(conditions,
				"EXISTS (SELECT 1 FROM media_item_libraries mil_scope_any WHERE mil_scope_any.content_id = mi.content_id)",
			)
		}
		conditions = append(conditions, fmt.Sprintf(
			"NOT EXISTS (SELECT 1 FROM media_item_libraries mil_scope_out WHERE mil_scope_out.content_id = mi.content_id AND mil_scope_out.media_folder_id = ANY($%d))",
			argIdx,
		))
		args = append(args, append([]int(nil), disabledLibraryIDs...))
		argIdx++
	}

	return fromClause, conditions, args, argIdx
}

func fetchSortClause(sort, order string) string {
	dir := "DESC"
	if order == "asc" {
		dir = "ASC"
	}
	switch sort {
	case "rating":
		return fmt.Sprintf("ORDER BY mi.rating_imdb %s NULLS LAST", dir)
	case "year":
		return fmt.Sprintf("ORDER BY mi.year %s", dir)
	case "title":
		return fmt.Sprintf("ORDER BY mi.sort_title %s", dir)
	default:
		return fmt.Sprintf("ORDER BY mi.created_at %s", dir)
	}
}

func intersectLibraryIDs(a, b []int) []int {
	if len(a) == 0 || len(b) == 0 {
		return nil
	}
	allowed := make(map[int]struct{}, len(b))
	for _, value := range b {
		allowed[value] = struct{}{}
	}
	var result []int
	seen := make(map[int]struct{})
	for _, value := range a {
		if _, ok := allowed[value]; !ok {
			continue
		}
		if _, ok := seen[value]; ok {
			continue
		}
		seen[value] = struct{}{}
		result = append(result, value)
	}
	return result
}

// applyConfigTypeFilter adds a WHERE condition for the config's filter_type.
func applyConfigTypeFilter(alias string, filterType string, conditions *[]string, args *[]any, argIdx *int) {
	if filterType == "" {
		return
	}
	*conditions = append(*conditions, fmt.Sprintf("%s.type = $%d", alias, *argIdx))
	*args = append(*args, filterType)
	*argIdx++
}

func matchesContinueWatchingFilter(filterType string, itemType string) bool {
	switch filterType {
	case "movie", "series", "episode":
		return ContinueTypeMatchesItem(ContinueTypeWatching, itemType)
	case "audiobook":
		return ContinueTypeMatchesItem(ContinueTypeListening, itemType)
	case "ebook":
		return ContinueTypeMatchesItem(ContinueTypeReading, itemType)
	default:
		return true
	}
}

// fetchSeasonalThemed returns items for a seasonal_themed section.
//
// Multi-theme mode (EnabledThemes set): picks the highest-priority enabled
// theme whose predicate matches now and queries items for that theme. Off-
// season (no enabled theme matches) the section is empty and gets suppressed
// by the API dispatcher.
//
// Legacy single-theme mode (Theme set, EnabledThemes empty): mode controls
// suppression — "auto" hides off-season, "pinned" always renders.
func (f *Fetcher) fetchSeasonalThemed(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.SeasonalThemedParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}

	now := time.Now()
	if f.Clock != nil {
		now = f.Clock.Now()
	}

	// Resolve which theme to use. Multi-theme mode wins when populated.
	// Selection skips themes without an executable query so a data-less theme
	// never blacks out the section during its own window (see
	// ActiveSeasonalThemeWhere).
	var theme string
	switch {
	case len(p.EnabledThemes) > 0:
		theme = recipes.ActiveSeasonalThemeWhere(p.EnabledThemes, now, seasonalThemeHasQuery)
		if theme == "" {
			// No enabled theme is currently in season — hide the section.
			return []*models.MediaItem{}, 0, nil
		}
	case p.Theme != "":
		// Legacy single-theme path with mode-based suppression.
		pred, ok := recipes.SeasonalPredicates[p.Theme]
		if !ok {
			return []*models.MediaItem{}, 0, nil
		}
		mode := p.Mode
		if mode == "" {
			mode = "auto"
		}
		if mode == "auto" && !pred(now) {
			return []*models.MediaItem{}, 0, nil
		}
		theme = p.Theme
	default:
		return []*models.MediaItem{}, 0, nil
	}

	def, hasQuery := seasonalQueryDef(theme)
	if !hasQuery {
		if keywords := seasonalKeywordTitles[theme]; len(keywords) > 0 {
			return f.fetchSeasonalKeywordItems(ctx, keywords, s, libraryID, libraryIDs, filter)
		}
		// Legacy single-theme path can still pin a theme without an
		// executable query. Return empty until that data lands.
		return []*models.MediaItem{}, 0, nil
	}

	// Apply library scope the same way fetchFiltered / fetchEditorialSpotlight do.
	switch {
	case libraryID != nil:
		def.LibraryIDs = []int{*libraryID}
	case libraryIDs != nil:
		if len(def.LibraryIDs) == 0 {
			def.LibraryIDs = append([]int(nil), libraryIDs...)
		} else {
			def.LibraryIDs = intersectLibraryIDs(def.LibraryIDs, libraryIDs)
		}
	}

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}
	def.Limit = &limit

	executor := &catalog.QueryExecutor{Pool: f.pool}
	items, _, _, err := executor.PreviewPage(ctx, def, filter, limit, 0, false)
	if err != nil {
		return nil, 0, fmt.Errorf("seasonal_themed query: %w", err)
	}
	return items, len(items), nil
}

// seasonalQueryDef returns a catalog.QueryDefinition for the given theme and
// whether an executable query exists. Holiday themes without genre signal
// (christmas, st_patricks, thanksgiving) use title-keyword matching as an
// interim heuristic until a proper keyword/tag column lands — imperfect but
// far better than the section going dark during the holiday itself.
func seasonalQueryDef(theme string) (catalog.QueryDefinition, bool) {
	newDef := func(rules ...catalog.QueryRule) catalog.QueryDefinition {
		return catalog.QueryDefinition{
			Match: "all",
			Groups: []catalog.QueryGroup{
				{Match: "any", Rules: rules},
			},
		}
	}
	rule := func(field, op, value string) catalog.QueryRule {
		return catalog.QueryRule{Field: field, Op: op, Value: value}
	}

	switch theme {
	case "halloween":
		return newDef(
			rule("genre", "contains", "Horror"),
			rule("genre", "contains", "Thriller"),
		), true
	case "valentines":
		return newDef(
			rule("genre", "contains", "Romance"),
		), true
	case "summer", "summer_blockbuster":
		return newDef(
			rule("genre", "contains", "Action"),
			rule("genre", "contains", "Adventure"),
		), true
	case "saturday_morning":
		return newDef(
			rule("genre", "contains", "Animation"),
			rule("genre", "contains", "Family"),
		), true
	case "family_movie_night":
		return newDef(
			rule("genre", "contains", "Family"),
			rule("genre", "contains", "Animation"),
		), true
	default:
		return catalog.QueryDefinition{}, false
	}
}

// seasonalKeywordTitles maps holiday themes without genre signal to title
// keywords, matched case-insensitively as substrings. An interim heuristic
// until a proper keyword/tag column lands — imperfect, but far better than
// the section going dark during the holiday itself.
var seasonalKeywordTitles = map[string][]string{
	"christmas":    {"christmas", "santa", "xmas", "nutcracker", "scrooge", "grinch", "noel"},
	"st_patricks":  {"st. patrick", "leprechaun", "shamrock"},
	"thanksgiving": {"thanksgiving"},
}

// seasonalThemeHasQuery reports whether a theme can produce items (either a
// genre query or a title-keyword fallback). Passed to
// ActiveSeasonalThemeWhere so multi-theme selection never picks a theme that
// would resolve to nothing.
func seasonalThemeHasQuery(theme string) bool {
	if _, ok := seasonalQueryDef(theme); ok {
		return true
	}
	return len(seasonalKeywordTitles[theme]) > 0
}

// fetchSeasonalKeywordItems resolves a keyword-based seasonal theme with a
// direct title ILIKE query (the QueryDefinition system has no title filter
// field). Ordering favors well-rated titles.
func (f *Fetcher) fetchSeasonalKeywordItems(ctx context.Context, keywords []string, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var conditions []string
	var args []any
	argIdx := 1

	patterns := make([]string, 0, len(keywords))
	for _, kw := range keywords {
		patterns = append(patterns, "%"+kw+"%")
	}
	conditions = append(conditions, fmt.Sprintf("mi.title ILIKE ANY($%d)", argIdx))
	args = append(args, patterns)
	argIdx++

	conditions = append(conditions, "mi.type IN ('movie','series')")

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	conditions = append(conditions, catalog.MangaChapterExclusionWhere("mi"))

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	query := fmt.Sprintf(
		`SELECT %s FROM %s WHERE %s ORDER BY mi.rating_imdb DESC NULLS LAST, mi.content_id ASC LIMIT $%d`,
		itemColumns("mi"), fromClause, strings.Join(conditions, " AND "), argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching seasonal keyword items: %w", err)
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

// fetchMoodCollection returns items for a mood_collection section.
func (f *Fetcher) fetchMoodCollection(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.MoodCollectionParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}

	info, ok := recipes.MoodByKey(p.Mood)
	if !ok {
		return []*models.MediaItem{}, 0, nil
	}

	// Build genre rules (OR'd together).
	genreRules := make([]catalog.QueryRule, 0, len(info.GenresAny))
	for _, genre := range info.GenresAny {
		genreRules = append(genreRules, catalog.QueryRule{Field: "genre", Op: "contains", Value: genre})
	}

	def := catalog.QueryDefinition{
		Match: "all",
		Groups: []catalog.QueryGroup{
			{Match: "any", Rules: genreRules},
			{Match: "all", Rules: []catalog.QueryRule{
				{Field: "rating_imdb", Op: "gte", Value: info.MinRating},
			}},
		},
	}

	switch {
	case libraryID != nil:
		def.LibraryIDs = []int{*libraryID}
	case libraryIDs != nil:
		if len(def.LibraryIDs) == 0 {
			def.LibraryIDs = append([]int(nil), libraryIDs...)
		} else {
			def.LibraryIDs = intersectLibraryIDs(def.LibraryIDs, libraryIDs)
		}
	}

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}
	def.Limit = &limit

	executor := &catalog.QueryExecutor{Pool: f.pool}
	items, _, _, err := executor.PreviewPage(ctx, def, filter, limit, 0, false)
	if err != nil {
		return nil, 0, fmt.Errorf("mood_collection query: %w", err)
	}
	return items, len(items), nil
}

// fetchShortWatches returns well-rated movies whose runtime fits under the
// configured cap — a "fits in a short evening" rail.
func (f *Fetcher) fetchShortWatches(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.ShortWatchesParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	if p.MaxMinutes <= 0 {
		p.MaxMinutes = 95
	}
	minRating := p.MinRating
	if minRating == 0 {
		minRating = 6.0
	}

	var conditions []string
	var args []any
	argIdx := 1

	conditions = append(conditions,
		"mi.type = 'movie'",
		fmt.Sprintf("mi.runtime > 0 AND mi.runtime <= $%d", argIdx),
	)
	args = append(args, p.MaxMinutes)
	argIdx++

	conditions = append(conditions, fmt.Sprintf("mi.rating_imdb >= $%d", argIdx))
	args = append(args, minRating)
	argIdx++

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	query := fmt.Sprintf(
		`SELECT %s FROM %s WHERE %s ORDER BY mi.rating_imdb DESC NULLS LAST, mi.content_id ASC LIMIT $%d`,
		itemColumns("mi"), fromClause, strings.Join(conditions, " AND "), argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching short watches: %w", err)
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

// fetchAnniversaries returns movies whose release month matches the current
// month and whose age is a round milestone (default: multiples of 5 years).
// Series are excluded: first_air_date is a free-text column, so anniversary
// math on it would be unreliable.
func (f *Fetcher) fetchAnniversaries(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	var p recipes.AnniversariesParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	milestone := p.MilestoneYears
	if milestone <= 0 {
		milestone = 5
	}

	now := f.now()

	var conditions []string
	var args []any
	argIdx := 1

	conditions = append(conditions,
		"mi.type = 'movie'",
		"mi.release_date IS NOT NULL",
		fmt.Sprintf("EXTRACT(MONTH FROM mi.release_date)::int = $%d", argIdx),
		fmt.Sprintf("EXTRACT(YEAR FROM mi.release_date)::int < $%d", argIdx+1),
	)
	args = append(args, int(now.Month()), now.Year())
	argIdx += 2

	if milestone > 1 {
		conditions = append(conditions, fmt.Sprintf("($%d - EXTRACT(YEAR FROM mi.release_date)::int) %% $%d = 0", argIdx, argIdx+1))
		args = append(args, now.Year(), milestone)
		argIdx += 2
	}

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	query := fmt.Sprintf(
		`SELECT %s FROM %s WHERE %s ORDER BY mi.rating_imdb DESC NULLS LAST, mi.content_id ASC LIMIT $%d`,
		itemColumns("mi"), fromClause, strings.Join(conditions, " AND "), argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching anniversaries: %w", err)
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

// fetchReturningShows returns series the profile has watched that received a
// brand-new season (episodes in a season newer than any the profile has
// watched, with at least one present file) within the lookback window,
// newest arrivals first.
func (f *Fetcher) fetchReturningShows(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, userID int, profileID string, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	if userID <= 0 || profileID == "" {
		return []*models.MediaItem{}, 0, nil
	}

	var p recipes.ReturningShowsParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	days := p.LookbackDays
	if days <= 0 {
		days = 30
	}

	// The new-season file check below must only count files in libraries the
	// viewer can actually reach: section scope intersected with the viewer's
	// allowed set, minus disabled libraries. Without this, a file that only
	// exists in an out-of-scope folder would surface the series here.
	scopeIDs := libraryIDs
	if libraryID != nil {
		scopeIDs = []int{*libraryID}
	}
	allowedFolders := filter.AllowedLibraryIDs
	if len(scopeIDs) > 0 {
		if allowedFolders != nil {
			allowedFolders = intersectLibraryIDs(scopeIDs, allowedFolders)
			if len(allowedFolders) == 0 {
				return []*models.MediaItem{}, 0, nil
			}
		} else {
			allowedFolders = scopeIDs
		}
	} else if allowedFolders != nil && len(allowedFolders) == 0 {
		return []*models.MediaItem{}, 0, nil
	}

	var conditions []string
	var args []any

	// $1..$3 are shared by several subqueries below.
	args = append(args, userID, profileID, days)
	argIdx := 4

	fileScopeCond := ""
	if len(allowedFolders) > 0 {
		fileScopeCond += fmt.Sprintf("\n\t\t\t\t  AND mf.media_folder_id = ANY($%d)", argIdx)
		args = append(args, allowedFolders)
		argIdx++
	}
	if len(filter.DisabledLibraryIDs) > 0 {
		fileScopeCond += fmt.Sprintf("\n\t\t\t\t  AND NOT (mf.media_folder_id = ANY($%d))", argIdx)
		args = append(args, filter.DisabledLibraryIDs)
		argIdx++
	}

	conditions = append(conditions,
		"mi.type = 'series'",
		// The profile has watched at least one episode of this series...
		`EXISTS (
			SELECT 1
			FROM episodes we
			JOIN user_watch_history uwh ON uwh.media_item_id = we.content_id
			WHERE we.series_id = mi.content_id
			  AND uwh.user_id = $1
			  AND uwh.profile_id = $2
		)`,
		// ...and a season newer than any they've watched arrived recently
		// with at least one playable file in an in-scope library.
		fmt.Sprintf(`EXISTS (
			SELECT 1
			FROM episodes ne
			WHERE ne.series_id = mi.content_id
			  AND ne.season_number > 0
			  AND ne.created_at > NOW() - ($3 || ' days')::interval
			  AND ne.season_number > COALESCE((
				SELECT MAX(we2.season_number)
				FROM episodes we2
				JOIN user_watch_history uwh2 ON uwh2.media_item_id = we2.content_id
				WHERE we2.series_id = mi.content_id
				  AND uwh2.user_id = $1
				  AND uwh2.profile_id = $2
			  ), 0)
			  AND EXISTS (
				SELECT 1 FROM media_files mf
				WHERE mf.episode_id = ne.content_id
				  AND mf.missing_since IS NULL%s
			  )
		)`, fileScopeCond),
	)

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}

	query := fmt.Sprintf(
		`SELECT %s FROM %s WHERE %s
		ORDER BY (
			SELECT MAX(ord.created_at)
			FROM episodes ord
			WHERE ord.series_id = mi.content_id
			  AND ord.created_at > NOW() - ($3 || ' days')::interval
		) DESC NULLS LAST, mi.content_id ASC
		LIMIT $%d`,
		itemColumns("mi"), fromClause, strings.Join(conditions, " AND "), argIdx,
	)
	args = append(args, limit)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, 0, fmt.Errorf("fetching returning shows: %w", err)
	}
	defer rows.Close()

	items, err := scanMediaItems(rows)
	if err != nil {
		return nil, 0, err
	}
	return items, len(items), nil
}

// fetchGenreRoulette is the title-less fallback used by fetchSection; FetchOne
// intercepts genre_roulette to surface the rotating genre in the row title,
// mirroring the editorial_spotlight flow.
func (f *Fetcher) fetchGenreRoulette(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, error) {
	items, total, _, err := f.fetchGenreRouletteWithTitle(ctx, s, libraryID, libraryIDs, filter)
	return items, total, err
}

// fetchGenreRouletteWithTitle picks one of the library's top genres with the
// same deterministic bucket hashing as editorial_spotlight and returns its
// best-rated titles plus a display title carrying the active genre.
func (f *Fetcher) fetchGenreRouletteWithTitle(ctx context.Context, s ResolvedSection, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]*models.MediaItem, int, string, error) {
	var p recipes.GenreRouletteParams
	if len(s.Config) > 0 {
		_ = json.Unmarshal(s.Config, &p)
	}
	minRating := p.MinRating
	if minRating == 0 {
		minRating = 6.0
	}

	cands, err := f.cachedEditorialCandidates(ctx, "genre_roulette", libraryID, libraryIDs, filter, editorialCandidateCacheTTL, f.genreRouletteCandidates)
	if err != nil {
		return nil, 0, "", fmt.Errorf("genre_roulette candidates: %w", err)
	}
	if len(cands) == 0 {
		return []*models.MediaItem{}, 0, "", nil
	}

	days := editorialCadenceDays(p.RotationCadence)
	libKey := "all"
	switch {
	case libraryID != nil:
		libKey = strconv.Itoa(*libraryID)
	case len(libraryIDs) > 0:
		// Multi-library scopes must not share one rotation bucket, or two
		// differently-scoped roulette rows would always advance in lockstep.
		parts := make([]string, len(libraryIDs))
		for i, id := range libraryIDs {
			parts[i] = strconv.Itoa(id)
		}
		libKey = strings.Join(parts, ",")
	}
	idx := recipes.RotationIndex(f.now(), "genre_roulette|"+libKey, len(cands), days)
	genre := cands[idx]

	def := catalog.QueryDefinition{
		Match: "all",
		Groups: []catalog.QueryGroup{
			{Match: "all", Rules: []catalog.QueryRule{
				{Field: "genre", Op: "contains", Value: genre},
				{Field: "rating_imdb", Op: "gte", Value: minRating},
			}},
		},
	}

	switch {
	case libraryID != nil:
		def.LibraryIDs = []int{*libraryID}
	case libraryIDs != nil:
		def.LibraryIDs = append([]int(nil), libraryIDs...)
	}

	limit := s.ItemLimit
	if limit <= 0 {
		limit = 20
	}
	def.Limit = &limit

	executor := &catalog.QueryExecutor{Pool: f.pool}
	items, _, _, err := executor.PreviewPage(ctx, def.Normalize(), filter, limit, 0, false)
	if err != nil {
		return nil, 0, "", fmt.Errorf("genre_roulette query: %w", err)
	}
	return items, len(items), editorialSpotlightDisplayTitle(s.Title, genre), nil
}

// genreRouletteCandidates returns the most common genres in scope, mirroring
// topStudioCandidates. The subjectType parameter is fixed ("genre_roulette")
// and only exists to satisfy the shared candidate-loader signature.
func (f *Fetcher) genreRouletteCandidates(ctx context.Context, _ string, libraryID *int, libraryIDs []int, filter catalog.AccessFilter) ([]string, error) {
	var conditions []string
	var args []any
	argIdx := 1

	fromClause, libConditions, libArgs, newArgIdx := buildLibraryScope(libraryID, libraryIDs, nil, filter.DisabledLibraryIDs, argIdx)
	conditions = append(conditions, libConditions...)
	args = append(args, libArgs...)
	argIdx = newArgIdx
	catalog.ApplySectionAccessFilter("mi", filter, &conditions, &args, &argIdx)

	whereClause := ""
	if len(conditions) > 0 {
		whereClause = "AND " + strings.Join(conditions, " AND ")
	}

	args = append(args, editorialCandidateLimit)
	query := fmt.Sprintf(`
		SELECT genre
		FROM (
			SELECT unnest(mi.genres) AS genre
			FROM %s
			WHERE mi.genres IS NOT NULL
			%s
		) sub
		GROUP BY genre
		ORDER BY COUNT(*) DESC
		LIMIT $%d
	`, fromClause, whereClause, argIdx)

	rows, err := f.pool.Query(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("querying top genres: %w", err)
	}
	defer rows.Close()

	var genres []string
	for rows.Next() {
		var genre string
		if err := rows.Scan(&genre); err != nil {
			return nil, fmt.Errorf("scanning genre name: %w", err)
		}
		genres = append(genres, genre)
	}
	return genres, rows.Err()
}

// mangaChapterSeriesMetaQuery resolves the owning manga series for chapter
// items (type='ebook' rows linked via manga_chapters) appearing on section
// cards, so continue-reading surfaces can show the series instead of the
// chapter's raw file title.
const mangaChapterSeriesMetaQuery = `
	SELECT mc.chapter_content_id, mc.series_content_id, si.title
	FROM manga_chapters mc
	JOIN media_items si ON si.content_id = mc.series_content_id
	WHERE mc.chapter_content_id = ANY($1)
`

// FetchMangaChapterSeriesMeta returns series linkage keyed by chapter content
// id. IDs that are not manga chapters simply have no entry.
func (f *Fetcher) FetchMangaChapterSeriesMeta(ctx context.Context, ids []string) (map[string]SectionItemMeta, error) {
	meta := make(map[string]SectionItemMeta, len(ids))
	if f == nil || f.pool == nil || len(ids) == 0 {
		return meta, nil
	}
	rows, err := f.pool.Query(ctx, mangaChapterSeriesMetaQuery, ids)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	for rows.Next() {
		var chapterID, seriesID, seriesTitle string
		if err := rows.Scan(&chapterID, &seriesID, &seriesTitle); err != nil {
			return nil, err
		}
		id := seriesID
		meta[chapterID] = SectionItemMeta{SeriesID: &id, SeriesTitle: seriesTitle}
	}
	return meta, rows.Err()
}

// applyMangaChapterSeriesMeta resolves the owning manga series for any chapter
// (ebook) items in the set and merges SeriesID/SeriesTitle into the existing
// itemMeta, preserving the progress fields already populated there. Lets the
// shared series-collapse group multiple in-progress chapters of one manga.
func (f *Fetcher) applyMangaChapterSeriesMeta(ctx context.Context, items []*models.MediaItem, itemMeta map[string]SectionItemMeta) {
	ids := make([]string, 0, len(items))
	for _, item := range items {
		if item != nil && item.Type == "ebook" && strings.TrimSpace(item.ContentID) != "" {
			ids = append(ids, item.ContentID)
		}
	}
	if len(ids) == 0 {
		return
	}
	seriesMeta, err := f.FetchMangaChapterSeriesMeta(ctx, ids)
	if err != nil {
		slog.WarnContext(ctx, "continue-reading: manga series linkage lookup failed", "component", "sections", "error", err)
		return
	}
	for chapterID, sm := range seriesMeta {
		m := itemMeta[chapterID]
		m.SeriesID = sm.SeriesID
		m.SeriesTitle = sm.SeriesTitle
		itemMeta[chapterID] = m
	}
}