feat(collections): playlist auto-creation, position ordering, hide_finished, Up Next, dashboard eligibility

Phase 2b + 3 of the metadata overhaul (plan §2.4, §3.1-3.7).

Auto-playlist collections (§2.4): the scanner turns obviously-playlist
sidecar series (explicit '(Reading Order)'/chronological/publication/
in-order/timeline markers only — precision over recall) into curated
static collections: upsert by view_settings.imported_from_series then
name (rename-safe), position set ONLY on insert (clean integers; 1.5/1a
stay unpositioned rather than guessing), membership add-if-missing,
never removed or re-ordered by rescans, provenance in description +
view_settings, show_on_dashboard true (dashboard-eligible by design),
'scanner.auto_playlist_collections' setting (default on, Settings
Registry + schema seed).

Ordering (§3.1-3.2): collection listings order position ASC NULLS LAST
then added_at ASC (was added_at DESC — walked playlists backwards);
PUT /api/collections/:id/items/order applies full-order rewrites
(owner-only, service-gated).

hide_finished + Up Next (§3.3-3.4): GetCollectionItemsForDashboard
gains viewer_user_id + hide_finished (LEFT JOIN reading_progress,
COALESCE percentage < 0.999) and viewer_percentage rides the row for
card graying; GetCollectionUpNext serves the collection's reading-queue
head with the family-lens visible-library array enforced.

Dashboard (§3.5): user collections are dashboard-ELIGIBLE BY DEFAULT —
the show_on_dashboard gate (never writable for user rows since the
column shipped) is gone from GetUserCollectionsForDashboard; hiding
stays dashboard-prefs (hidden_collections) territory; hide_finished
filtered-everything now emits a Complete section instead of silently
vanishing; sections JSON carries is_playlist/complete.

Series page ordering hardening (§3.6): GetSeriesBooks tiebreaks by
title ASC — NULL/tied numbers previously returned heap (scan) order,
which is what the user saw.

Frontend custom-section-builder note: the builder has sent
show_on_dashboard: true since its creation; the API never bound it.
User-row visibility is now intentionally prefs-governed, so the field
stays unbound by design (documented in code).

Pins widened (docs/contract_pins.md): collection detail + up_next;
dashboard sections + is_playlist/complete; new reorder endpoint
recorded.

Verified: TestPlaylistCollectionsEndToEnd (new, full e2e: sidecar
series split, collection auto-creation with position 7, rescan
idempotency, owner-only reorder, finished-filter + completion marker +
Up Next drain) plus the full affected integration sweep green.

internal/services/dashboard_service.go

@@ -24,6 +24,34 @@ func NewDashboardService(db *database.Queries) *DashboardService {
 	}
 }
 
+// viewSettingsFlag reads a boolean key from a collection's view_settings
+// JSONB. Malformed or absent → false.
+func viewSettingsFlag(raw []byte, key string) bool {
+	if len(raw) == 0 {
+		return false
+	}
+	var settings map[string]interface{}
+	if err := json.Unmarshal(raw, &settings); err != nil {
+		return false
+	}
+	b, ok := settings[key].(bool)
+	return ok && b
+}
+
+// viewSettingsHasKey reports whether the key exists at all (any value) —
+// used for provenance markers like imported_from_series.
+func viewSettingsHasKey(raw []byte, key string) bool {
+	if len(raw) == 0 {
+		return false
+	}
+	var settings map[string]interface{}
+	if err := json.Unmarshal(raw, &settings); err != nil {
+		return false
+	}
+	_, ok := settings[key]
+	return ok
+}
+
 type DashboardSection struct {
 	CollectionID   uuid.UUID
 	CollectionName string
@@ -34,6 +62,13 @@ type DashboardSection struct {
 	Title          string
 	Description    string
 	Icon           string
+	// A2c: the collection's own ordering-construct marker — the section is
+	// a curated playlist ("The Witcher (Reading Order)"), rendered with a
+	// badge by the frontend.
+	IsPlaylist bool
+	// A2c §3.5: hide_finished filtered every item out of a NON-empty
+	// collection — render "playlist complete" instead of dropping silently.
+	Complete bool
 }
 
 func (s *DashboardService) GetDashboardSections(
@@ -81,7 +116,29 @@ func (s *DashboardService) GetDashboardSections(
 			continue
 		}
 
+		// A2c §3.5: hide_finished filtered everything out — but the
+		// collection is NOT empty. That's a finished playlist: render a
+		// completion marker instead of silently vanishing.
 		if len(items) == 0 {
+			hideFinished := viewSettingsFlag(coll.ViewSettings, "hide_finished")
+			if hideFinished {
+				collUUIDBytes, _ := uuid.FromBytes(coll.ID.Bytes[0:16])
+				if count, countErr := s.db.CountCollectionItems(ctx, pgtype.UUID{Bytes: collUUIDBytes, Valid: true}); countErr == nil && count > 0 {
+					results = append(results, DashboardSection{
+						CollectionID:   coll.ID.Bytes,
+						CollectionName: coll.Name,
+						Items:          []database.MediaItems{},
+						QueryType:      coll.QueryType.String,
+						Priority:       int(coll.Priority.Int32),
+						IsSystem:       false,
+						Title:          coll.Name,
+						Description:    coll.Description.String,
+						Icon:           coll.Icon.String,
+						IsPlaylist:     viewSettingsHasKey(coll.ViewSettings, "imported_from_series"),
+						Complete:       true,
+					})
+				}
+			}
 			continue
 		}
 
@@ -95,6 +152,7 @@ func (s *DashboardService) GetDashboardSections(
 			Title:          coll.Name,
 			Description:    coll.Description.String,
 			Icon:           coll.Icon.String,
+			IsPlaylist:     viewSettingsHasKey(coll.ViewSettings, "imported_from_series"),
 		})
 	}
 
@@ -218,9 +276,15 @@ func (s *DashboardService) getCollectionItemsByQueryType(ctx context.Context, co
 func (s *DashboardService) getUserCollectionItems(ctx context.Context, coll database.Collections, userID uuid.UUID, libraryID pgtype.UUID, limit int) ([]database.MediaItems, error) {
 	collUUID, _ := uuid.FromBytes(coll.ID.Bytes[0:16])
 
+	// A2c §3.3: per-collection hide_finished (view_settings), evaluated
+	// against the VIEWER's reading progress. The section then shows the
+	// head of the reading queue in playlist order.
+	hideFinished := viewSettingsFlag(coll.ViewSettings, "hide_finished")
 	manualItems, err := s.db.GetCollectionItemsForDashboard(ctx, database.GetCollectionItemsForDashboardParams{
 		CollectionID: pgtype.UUID{Bytes: collUUID, Valid: true},
 		LibraryID:    libraryID,
+		ViewerUserID: pgtype.UUID{Bytes: userID, Valid: true},
+		HideFinished: pgtype.Bool{Bool: hideFinished, Valid: true},
 		Limit:        pgtype.Int4{Int32: int32(limit), Valid: true},
 	})
 	if err != nil {