feat(collections): smart (dynamic) collections — rules evaluated live at render

Type is DERIVED, not stored: a saved ruleset makes a collection SMART,
no rules = STATIC (stored collection_items links, unchanged behavior).
No schema change — collections.auto_assign_rules JSONB already carried
the config; user's decision 2026-10-14 (handoff: live-at-render, not
refresh-on-scan; create-time Static/Smart toggle; v1 NO hybrid).

- Rule gains an enabled flag (absent = enabled, legacy rules unaffected).
- Rule CRUD: POST/PUT(DELETE) /api/collections/:id/rules[/:ruleId] — the
  survivor dead effort of the rules-builder UI finally has real
  endpoints (rules were never editable after creation; nothing ever
  re-evaluated them). First rule converts a user collection to smart;
  removing the last reverts it to static. UpdateCollectionRulesJSON
  edits ONLY the rules doc so rule CRUD cannot clobber metadata.
- Live evaluation: candidates from GetVisibleLiveMediaForRules —
  visible-library set (family lens enforced at source) + archived IS
  NULL AND missing_scan_count = 0 — any enabled rule matches, title
  order. Zero refresh hooks by design: always current by construction.
- Membership mutations (add/remove/bulk-add) are 400 on smart — v1 no
  hybrid; collection_items.excluded stays the reserved future hook.
- Rules builder page (/collections/:id/rules) first time ever routable;
  templ whole-attribute interpolation ("{ expr }" inside a quoted attr
  value is literal text, as theme-{ user.Theme } silently proved).
- UI: create modal Static/⚡Smart cards (smart create redirects into the
  rules builder), ⚡ badge + real per-card counts on the grid (smart =
  live matches, static = stored-link count), smart detail renders
  matched books with no hand-pick actions + an Edit Rules button.
- API: GET /:id gains is_smart + live books; GET /: keeps the Android
  app's default exclusion, include_auto=true surfaces smart rows with
  live counts; TestRules previews against the SAME candidates the live
  render uses (visible + live, was raw first-1000).
- FIXED pre-existing regression from 7ce7321: static collection detail
  with NO library_id returned zero books — QueryType != '' caught user
  rows ('filter' default) and routed them to dashboard sections that
  never contain them; now only real system query types go there
  (handlers + SSR). App-visible symptom: /api/collections/:id without
  library_id came back books:[] for every static collection.

Tests: collections_smart_test.go (conversion, disabled rules, mutation
guards, revert-to-static, validation, system-collection prohibition,
include_auto semantics). Full offline integration suite PASS.

internal/database/querier.go

@@ -42,6 +42,10 @@ type Querier interface {
 	ClearMediaItemMetadataOverrides(ctx context.Context, id pgtype.UUID) error
 	CountAdmins(ctx context.Context) (int64, error)
 	CountArchivedMediaItems(ctx context.Context) (int64, error)
+	// Live item count for a STATIC collection (rule-free cards on the
+	// collections page); same live filter as GetCollectionItems, plus the
+	// future-hybrid excluded exclusion and an optional library scope.
+	CountCollectionLiveItems(ctx context.Context, arg CountCollectionLiveItemsParams) (int32, error)
 	// Count unlinked books for a device
 	CountUnlinkedBooks(ctx context.Context, deviceID pgtype.UUID) (int64, error)
 	CountUserDevices(ctx context.Context, userID pgtype.UUID) (int64, error)
@@ -358,6 +362,12 @@ type Querier interface {
 	GetUserReadingHistory(ctx context.Context, arg GetUserReadingHistoryParams) ([]GetUserReadingHistoryRow, error)
 	GetUserVisibleLibraries(ctx context.Context, userID pgtype.UUID) ([]GetUserVisibleLibrariesRow, error)
 	GetVisibleLibraryMediaCounts(ctx context.Context, userID pgtype.UUID) ([]GetVisibleLibraryMediaCountsRow, error)
+	// Smart ("dynamic") collections: rules are evaluated LIVE at render, so
+	// membership comes from the candidate book set instead of collection_items.
+	// The set is scoped to the requesting user's visible libraries (family
+	// lens enforced at the source) and live items only — the same filters the
+	// static collection paths apply.
+	GetVisibleLiveMediaForRules(ctx context.Context, arg GetVisibleLiveMediaForRulesParams) ([]MediaItems, error)
 	HasRecentConflictResolution(ctx context.Context, arg HasRecentConflictResolutionParams) (bool, error)
 	IncrementSyncQueueAttempts(ctx context.Context, arg IncrementSyncQueueAttemptsParams) (SyncQueue, error)
 	// Check if book is in collection
@@ -474,6 +484,9 @@ type Querier interface {
 	TombstoneSystemCollection(ctx context.Context, id pgtype.UUID) error
 	// Update collection
 	UpdateCollection(ctx context.Context, arg UpdateCollectionParams) (Collections, error)
+	// Replace ONLY the auto_assign_rules document (rule CRUD: read-modify-write
+	// of the JSONB without touching metadata stale clients did not send).
+	UpdateCollectionRulesJSON(ctx context.Context, arg UpdateCollectionRulesJSONParams) (Collections, error)
 	UpdateDashboardPreferences(ctx context.Context, arg UpdateDashboardPreferencesParams) (UserDashboardPreferences, error)
 	UpdateDevice(ctx context.Context, arg UpdateDeviceParams) (Devices, error)
 	UpdateDeviceAuthToken(ctx context.Context, arg UpdateDeviceAuthTokenParams) (Devices, error)

internal/database/queries.sql.go

@@ -293,6 +293,31 @@ func (q *Queries) CountArchivedMediaItems(ctx context.Context) (int64, error) {
 	return count, err
 }
 
+const CountCollectionLiveItems = `-- name: CountCollectionLiveItems :one
+SELECT COUNT(*)::int FROM collection_items ci
+JOIN media_items mi ON ci.media_item_id = mi.id
+WHERE ci.collection_id = $1
+  AND NOT COALESCE(ci.excluded, false)
+  AND ($2::uuid IS NULL OR mi.library_id = $2::uuid)
+  AND mi.archived_at IS NULL
+  AND mi.missing_scan_count = 0
+`
+
+type CountCollectionLiveItemsParams struct {
+	CollectionID pgtype.UUID `db:"collection_id" json:"collection_id"`
+	LibraryID    pgtype.UUID `db:"library_id" json:"library_id"`
+}
+
+// Live item count for a STATIC collection (rule-free cards on the
+// collections page); same live filter as GetCollectionItems, plus the
+// future-hybrid excluded exclusion and an optional library scope.
+func (q *Queries) CountCollectionLiveItems(ctx context.Context, arg CountCollectionLiveItemsParams) (int32, error) {
+	row := q.db.QueryRow(ctx, CountCollectionLiveItems, arg.CollectionID, arg.LibraryID)
+	var column_1 int32
+	err := row.Scan(&column_1)
+	return column_1, err
+}
+
 const CountUnlinkedBooks = `-- name: CountUnlinkedBooks :one
 SELECT COUNT(*) as count
 FROM unlinked_books
@@ -8512,6 +8537,110 @@ func (q *Queries) GetVisibleLibraryMediaCounts(ctx context.Context, userID pgtyp
 	return items, nil
 }
 
+const GetVisibleLiveMediaForRules = `-- name: GetVisibleLiveMediaForRules :many
+SELECT mi.id, mi.library_id, mi.title, mi.author, mi.isbn, mi.description, mi.file_path, mi.file_size, mi.mime_type, mi.cover_image_path, mi.series, mi.series_number, mi.tags, mi.asin, mi.date_published, mi.publisher, mi.contributors, mi.language, mi.edition, mi.page_count, mi.genre, mi.copyright_year, mi.goodreads_id, mi.openlibrary_id, mi.google_books_id, mi.added_by_admin_id, mi.created_at, mi.imported_at, mi.updated_at, mi.format_group, mi.format_mimetype, mi.is_reflowable, mi.has_fixed_layout, mi.total_characters, mi.chapter_count, mi.entitlement_id, mi.revision_number, mi.kobo_content_id, mi.kobo_metadata, mi.manga_type, mi.reading_direction, mi.series_count, mi.volume, mi.imprint, mi.age_rating, mi.web_url, mi.story_arc, mi.is_black_and_white, mi.metadata_notes, mi.community_rating, mi.alternate_info, mi.scan_information, mi.summary, mi.metadata_overrides, mi.missing_scan_count, mi.archived_at, mi.chapter_metadata, mi.library_type_name, mi.tags_search, mi.contributors_search, mi.file_sha256, mi.opf_identifier, mi.opf_uuid, mi.hash_confidence FROM media_items mi
+WHERE ($1::uuid IS NULL OR mi.library_id = $1::uuid)
+  AND ($2::uuid[] IS NULL OR mi.library_id = ANY($2::uuid[]))
+  AND mi.archived_at IS NULL
+  AND mi.missing_scan_count = 0
+ORDER BY mi.title ASC
+`
+
+type GetVisibleLiveMediaForRulesParams struct {
+	LibraryID         pgtype.UUID   `db:"library_id" json:"library_id"`
+	VisibleLibraryIds []pgtype.UUID `db:"visible_library_ids" json:"visible_library_ids"`
+}
+
+// Smart ("dynamic") collections: rules are evaluated LIVE at render, so
+// membership comes from the candidate book set instead of collection_items.
+// The set is scoped to the requesting user's visible libraries (family
+// lens enforced at the source) and live items only — the same filters the
+// static collection paths apply.
+func (q *Queries) GetVisibleLiveMediaForRules(ctx context.Context, arg GetVisibleLiveMediaForRulesParams) ([]MediaItems, error) {
+	rows, err := q.db.Query(ctx, GetVisibleLiveMediaForRules, arg.LibraryID, arg.VisibleLibraryIds)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	items := []MediaItems{}
+	for rows.Next() {
+		var i MediaItems
+		if err := rows.Scan(
+			&i.ID,
+			&i.LibraryID,
+			&i.Title,
+			&i.Author,
+			&i.Isbn,
+			&i.Description,
+			&i.FilePath,
+			&i.FileSize,
+			&i.MimeType,
+			&i.CoverImagePath,
+			&i.Series,
+			&i.SeriesNumber,
+			&i.Tags,
+			&i.Asin,
+			&i.DatePublished,
+			&i.Publisher,
+			&i.Contributors,
+			&i.Language,
+			&i.Edition,
+			&i.PageCount,
+			&i.Genre,
+			&i.CopyrightYear,
+			&i.GoodreadsID,
+			&i.OpenlibraryID,
+			&i.GoogleBooksID,
+			&i.AddedByAdminID,
+			&i.CreatedAt,
+			&i.ImportedAt,
+			&i.UpdatedAt,
+			&i.FormatGroup,
+			&i.FormatMimetype,
+			&i.IsReflowable,
+			&i.HasFixedLayout,
+			&i.TotalCharacters,
+			&i.ChapterCount,
+			&i.EntitlementID,
+			&i.RevisionNumber,
+			&i.KoboContentID,
+			&i.KoboMetadata,
+			&i.MangaType,
+			&i.ReadingDirection,
+			&i.SeriesCount,
+			&i.Volume,
+			&i.Imprint,
+			&i.AgeRating,
+			&i.WebUrl,
+			&i.StoryArc,
+			&i.IsBlackAndWhite,
+			&i.MetadataNotes,
+			&i.CommunityRating,
+			&i.AlternateInfo,
+			&i.ScanInformation,
+			&i.Summary,
+			&i.MetadataOverrides,
+			&i.MissingScanCount,
+			&i.ArchivedAt,
+			&i.ChapterMetadata,
+			&i.LibraryTypeName,
+			&i.TagsSearch,
+			&i.ContributorsSearch,
+			&i.FileSha256,
+			&i.OpfIdentifier,
+			&i.OpfUuid,
+			&i.HashConfidence,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const HasRecentConflictResolution = `-- name: HasRecentConflictResolution :one
 SELECT EXISTS(
     SELECT 1 FROM sync_conflicts
@@ -12383,6 +12512,39 @@ func (q *Queries) UpdateCollection(ctx context.Context, arg UpdateCollectionPara
 	return i, err
 }
 
+const UpdateCollectionRulesJSON = `-- name: UpdateCollectionRulesJSON :one
+UPDATE collections SET auto_assign_rules = $2 WHERE id = $1 RETURNING id, user_id, name, description, color, icon, auto_assign_rules, view_settings, show_on_dashboard, query_type, priority, is_system_collection, created_at, deleted_at
+`
+
+type UpdateCollectionRulesJSONParams struct {
+	ID              pgtype.UUID `db:"id" json:"id"`
+	AutoAssignRules []byte      `db:"auto_assign_rules" json:"auto_assign_rules"`
+}
+
+// Replace ONLY the auto_assign_rules document (rule CRUD: read-modify-write
+// of the JSONB without touching metadata stale clients did not send).
+func (q *Queries) UpdateCollectionRulesJSON(ctx context.Context, arg UpdateCollectionRulesJSONParams) (Collections, error) {
+	row := q.db.QueryRow(ctx, UpdateCollectionRulesJSON, arg.ID, arg.AutoAssignRules)
+	var i Collections
+	err := row.Scan(
+		&i.ID,
+		&i.UserID,
+		&i.Name,
+		&i.Description,
+		&i.Color,
+		&i.Icon,
+		&i.AutoAssignRules,
+		&i.ViewSettings,
+		&i.ShowOnDashboard,
+		&i.QueryType,
+		&i.Priority,
+		&i.IsSystemCollection,
+		&i.CreatedAt,
+		&i.DeletedAt,
+	)
+	return i, err
+}
+
 const UpdateDashboardPreferences = `-- name: UpdateDashboardPreferences :one
 UPDATE user_dashboard_preferences
 SET hidden_collections = $2,

internal/database/queries/queries.sql

@@ -2190,6 +2190,11 @@ SET
 WHERE id = $1
 RETURNING *;
 
+-- Replace ONLY the auto_assign_rules document (rule CRUD: read-modify-write
+-- of the JSONB without touching metadata stale clients did not send).
+-- name: UpdateCollectionRulesJSON :one
+UPDATE collections SET auto_assign_rules = $2 WHERE id = $1 RETURNING *;
+
 -- Delete collection
 -- name: DeleteCollection :exec
 DELETE FROM collections WHERE id = $1;
@@ -2628,6 +2633,31 @@ WHERE ci.collection_id = sqlc.narg('collection_id')
 ORDER BY ci.added_at DESC
 LIMIT sqlc.narg('limit');
 
+-- Smart ("dynamic") collections: rules are evaluated LIVE at render, so
+-- membership comes from the candidate book set instead of collection_items.
+-- The set is scoped to the requesting user's visible libraries (family
+-- lens enforced at the source) and live items only — the same filters the
+-- static collection paths apply.
+-- name: GetVisibleLiveMediaForRules :many
+SELECT mi.* FROM media_items mi
+WHERE (sqlc.narg('library_id')::uuid IS NULL OR mi.library_id = sqlc.narg('library_id')::uuid)
+  AND (sqlc.narg('visible_library_ids')::uuid[] IS NULL OR mi.library_id = ANY(sqlc.narg('visible_library_ids')::uuid[]))
+  AND mi.archived_at IS NULL
+  AND mi.missing_scan_count = 0
+ORDER BY mi.title ASC;
+
+-- Live item count for a STATIC collection (rule-free cards on the
+-- collections page); same live filter as GetCollectionItems, plus the
+-- future-hybrid excluded exclusion and an optional library scope.
+-- name: CountCollectionLiveItems :one
+SELECT COUNT(*)::int FROM collection_items ci
+JOIN media_items mi ON ci.media_item_id = mi.id
+WHERE ci.collection_id = $1
+  AND NOT COALESCE(ci.excluded, false)
+  AND (sqlc.narg('library_id')::uuid IS NULL OR mi.library_id = sqlc.narg('library_id')::uuid)
+  AND mi.archived_at IS NULL
+  AND mi.missing_scan_count = 0;
+
 -- name: GetLibraryItems :many
 SELECT mi.* FROM media_items mi
 WHERE (sqlc.narg('library_id')::uuid IS NULL OR mi.library_id = sqlc.narg('library_id')::uuid)

internal/handlers/collections.go

@@ -40,6 +40,7 @@ type CreateCollectionRequest struct {
 	Description     string                 `form:"description" json:"description"`
 	Color           string                 `form:"color" json:"color"`
 	Icon            string                 `form:"icon" json:"icon"`
+	CollectionType  string                 `form:"collection_type" json:"collection_type"` // "static" (default) or "smart" (rule-based)
 	AutoAssignRules []services.Rule        `form:"auto_assign_rules" json:"auto_assign_rules"`
 	ViewSettings    map[string]interface{} `form:"view_settings" json:"view_settings"`
 }
@@ -118,6 +119,7 @@ func (h *CollectionHandler) CreateCollection(c *echo.Context) error {
 	}
 
 	bookCount := int32(0)
+	isSmart := req.CollectionType == "smart" || len(req.AutoAssignRules) > 0
 	response := map[string]interface{}{
 		"id":                uuid.UUID(collection.ID.Bytes).String(),
 		"user_id":           uuid.UUID(collection.UserID.Bytes).String(),
@@ -125,6 +127,7 @@ func (h *CollectionHandler) CreateCollection(c *echo.Context) error {
 		"description":       textToString(collection.Description),
 		"color":             textToString(collection.Color),
 		"icon":              textToString(collection.Icon),
+		"collection_type":   map[bool]string{true: "smart", false: "static"}[isSmart],
 		"auto_assign_rules": collection.AutoAssignRules,
 		"view_settings":     collection.ViewSettings,
 		"book_count":        bookCount,
@@ -133,7 +136,13 @@ func (h *CollectionHandler) CreateCollection(c *echo.Context) error {
 
 	// Add redirect header for HTMX requests
 	if c.Request().Header.Get("HX-Request") == "true" {
-		c.Response().Header().Set("HX-Redirect", "/collections")
+		// A smart collection starts with an empty ruleset; the builder is
+		// where it becomes real. Static collections head back to the grid.
+		if isSmart {
+			c.Response().Header().Set("HX-Redirect", "/collections/"+uuid.UUID(collection.ID.Bytes).String()+"/rules")
+		} else {
+			c.Response().Header().Set("HX-Redirect", "/collections")
+		}
 	}
 
 	return c.JSON(http.StatusCreated, response)
@@ -158,31 +167,46 @@ func (h *CollectionHandler) GetCollections(c *echo.Context) error {
 		AutoAssignRules json.RawMessage `json:"auto_assign_rules"`
 		CreatedAt       string          `json:"created_at"`
 		BookCount       int             `json:"book_count"`
+		IsSmart         bool            `json:"is_smart"`
 	}
 
 	response := make([]CollectionResponse, 0, len(collections))
 	for _, col := range collections {
-		if !includeAuto && len(col.AutoAssignRules) > 0 {
+		isSmart := h.collectionService.IsSmartCollection(col.AutoAssignRules)
+		if !includeAuto && isSmart {
+			// Legacy default for API clients (the Android app pre-dates
+			// smart collections): rule-driven collections stay opt-in so
+			// their membership could never be stale for old readers.
 			continue
 		}
 
 		bookCount := 0
+		var libUUID pgtype.UUID
 		if libraryID != "" {
-			libUUID, libErr := uuid.Parse(libraryID)
-			if libErr == nil {
-				items, countErr := h.db.GetCollectionItemsForDashboard(c.Request().Context(), database.GetCollectionItemsForDashboardParams{
-					CollectionID: pgtype.UUID{Bytes: col.ID.Bytes, Valid: true},
-					LibraryID:    pgtype.UUID{Bytes: libUUID, Valid: true},
-					Limit:        pgtype.Int4{Int32: 10000, Valid: true},
+			if libParsed, libErr := uuid.Parse(libraryID); libErr == nil {
+				libUUID = pgtype.UUID{Bytes: libParsed, Valid: true}
+			}
+		}
+		if isSmart {
+			rules := h.collectionService.ParseRules(col.AutoAssignRules)
+			visibleIDs, visErr := h.userVisibleLibraryIDs(c)
+			if visErr == nil {
+				matches, evalErr := h.collectionService.EvaluateSmartCollection(c.Request().Context(), rules, services.SmartEvalOptions{
+					LibraryID:  libUUID,
+					VisibleIDs: visibleIDs,
 				})
-				if countErr == nil {
-					for _, item := range items {
-						if !item.Excluded.Valid || !item.Excluded.Bool {
-							bookCount++
-						}
-					}
+				if evalErr == nil {
+					bookCount = len(matches)
 				}
 			}
+		} else {
+			count, countErr := h.db.CountCollectionLiveItems(c.Request().Context(), database.CountCollectionLiveItemsParams{
+				CollectionID: pgtype.UUID{Bytes: col.ID.Bytes, Valid: true},
+				LibraryID:    libUUID,
+			})
+			if countErr == nil {
+				bookCount = int(count)
+			}
 		}
 
 		response = append(response, CollectionResponse{
@@ -194,6 +218,7 @@ func (h *CollectionHandler) GetCollections(c *echo.Context) error {
 			AutoAssignRules: col.AutoAssignRules,
 			CreatedAt:       col.CreatedAt.Time.String(),
 			BookCount:       bookCount,
+			IsSmart:         isSmart,
 		})
 	}
 
@@ -236,7 +261,31 @@ func (h *CollectionHandler) GetCollection(c *echo.Context) error {
 		libUUID = pgtype.UUID{Bytes: parsed, Valid: true}
 	}
 
-	if collection.QueryType.Valid && collection.QueryType.String != "" {
+	isSmart := h.collectionService.IsSmartCollection(collection.AutoAssignRules)
+	if isSmart {
+		rules := h.collectionService.ParseRules(collection.AutoAssignRules)
+		visibleIDs, err := h.userVisibleLibraryIDs(c)
+		if err != nil {
+			return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
+		}
+		matches, evalErr := h.collectionService.EvaluateSmartCollection(c.Request().Context(), rules, services.SmartEvalOptions{
+			LibraryID:  libUUID,
+			VisibleIDs: visibleIDs,
+		})
+		if evalErr != nil {
+			return c.JSON(http.StatusInternalServerError, map[string]string{"error": evalErr.Error()})
+		}
+		bookList = make([]BookInfo, 0, len(matches))
+		for _, item := range matches {
+			itemUUID, _ := uuid.FromBytes(item.ID.Bytes[0:16])
+			bookList = append(bookList, BookInfo{
+				MediaItemID:    itemUUID.String(),
+				Title:          item.Title,
+				Author:         textToString(item.Author),
+				CoverImagePath: utils.ResolveMediaURL(item.LibraryID, item.CoverImagePath),
+			})
+		}
+	} else if collection.IsSystemCollection.Bool && collection.QueryType.Valid && collection.QueryType.String != "" && collection.QueryType.String != "filter" {
 		user := c.Get("user").(database.Users)
 		userUUID := uuid.UUID(user.ID.Bytes)
 		dashboardSvc := services.NewDashboardService(h.db)
@@ -323,6 +372,7 @@ func (h *CollectionHandler) GetCollection(c *echo.Context) error {
 		"view_settings":     viewSettings,
 		"books":             bookList,
 		"book_count":        len(bookList),
+		"is_smart":          isSmart,
 		"created_at":        collection.CreatedAt.Time.String(),
 	})
 }
@@ -400,6 +450,10 @@ func (h *CollectionHandler) AddBooks(c *echo.Context) error {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
 	}
 
+	if guardErr := h.rejectSmartMutation(c, collectionID); guardErr != nil {
+		return guardErr
+	}
+
 	user := c.Get("user").(database.Users)
 	userUUID := uuid.UUID(user.ID.Bytes)
 
@@ -447,6 +501,10 @@ func (h *CollectionHandler) RemoveBook(c *echo.Context) error {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
 	}
 
+	if guardErr := h.rejectSmartMutation(c, collectionID); guardErr != nil {
+		return guardErr
+	}
+
 	bookID, err := uuid.Parse(c.Param("bookId"))
 	if err != nil {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid book id"})
@@ -487,6 +545,10 @@ func (h *CollectionHandler) BulkRemoveBooks(c *echo.Context) error {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
 	}
 
+	if guardErr := h.rejectSmartMutation(c, collectionID); guardErr != nil {
+		return guardErr
+	}
+
 	user := c.Get("user").(database.Users)
 	userUUID := uuid.UUID(user.ID.Bytes)
 
@@ -727,6 +789,170 @@ func (h *CollectionHandler) GetUserCollectionsList(c *echo.Context) ([]database.
 	return h.collectionService.GetUserCollections(c.Request().Context(), userUUID)
 }
 
+// userVisibleLibraryIDs loads the requester's visible-library set (the
+// family lens). Smart-collection evaluation funnels every book candidate
+// through it so hidden libraries contribute nothing.
+func (h *CollectionHandler) userVisibleLibraryIDs(c *echo.Context) ([]pgtype.UUID, error) {
+	user, ok := c.Get("user").(database.Users)
+	if !ok {
+		return nil, echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
+	}
+	rows, err := h.libraryService.GetUserVisibleLibraries(c.Request().Context(), user.ID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to check library access: %w", err)
+	}
+	ids := make([]pgtype.UUID, 0, len(rows))
+	for _, lib := range rows {
+		if lib.ID.Valid {
+			ids = append(ids, lib.ID)
+		}
+	}
+	return ids, nil
+}
+
+// UserVisibleLibraryIDs is the exported entry point for the router's
+// frontend page handlers, which resolve the visible-library set before
+// evaluating smart-collection rule matches.
+func (h *CollectionHandler) UserVisibleLibraryIDs(c *echo.Context) ([]pgtype.UUID, error) {
+	return h.userVisibleLibraryIDs(c)
+}
+
+// CollectionService returns the underlying service so the router's
+// frontend handlers can share the exact same evaluation the API uses.
+func (h *CollectionHandler) CollectionService() *services.CollectionService {
+	return h.collectionService
+}
+
+// rejectSmartMutation returns a 400 for smart collections: membership is
+// derived live from rules, so stored link mutations have nothing to act
+// on. v1 has no hybrid mode — add/remove with both rules and hand-picked
+// books is deliberately unsupported (collection_items.excluded awaits it).
+func (h *CollectionHandler) rejectSmartMutation(c *echo.Context, collectionID uuid.UUID) *echo.HTTPError {
+	collection, err := h.GetCollectionData(c, collectionID)
+	if err != nil {
+		return echo.NewHTTPError(http.StatusNotFound, "collection not found")
+	}
+	if h.collectionService.IsSmartCollection(collection.AutoAssignRules) {
+		return echo.NewHTTPError(http.StatusBadRequest, "smart collections are rule-based — membership is managed by the collection's rules, not by hand")
+	}
+	return nil
+}
+
+type AddRuleRequest struct {
+	Field    string `json:"field" validate:"required"`
+	Operator string `json:"operator" validate:"required"`
+	Value    string `json:"value" validate:"required"`
+	Enabled  *bool  `json:"enabled"`
+	Priority int    `json:"priority"`
+}
+
+// AddRule handles POST /api/collections/:id/rules — appends one rule to
+// the ruleset. The first rule converts a static collection to smart.
+func (h *CollectionHandler) AddRule(c *echo.Context) error {
+	collectionID, err := uuid.Parse(c.Param("id"))
+	if err != nil {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
+	}
+
+	collection, err := h.GetCollectionData(c, collectionID)
+	if err != nil {
+		return c.JSON(http.StatusNotFound, map[string]string{"error": "collection not found"})
+	}
+	if collection.IsSystemCollection.Bool {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "system collections cannot have rules"})
+	}
+
+	var req AddRuleRequest
+	if err := c.Bind(&req); err != nil {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
+	}
+	if err := c.Validate(&req); err != nil {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
+	}
+
+	updated, rule, err := h.collectionService.AddRule(c.Request().Context(), collectionID, services.Rule{
+		Field:    req.Field,
+		Operator: req.Operator,
+		Value:    req.Value,
+		Enabled:  req.Enabled,
+		Priority: req.Priority,
+	})
+	if err != nil {
+		var ruleErr *services.RuleValidationError
+		if errors.As(err, &ruleErr) {
+			return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
+		}
+		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
+	}
+
+	return c.JSON(http.StatusCreated, map[string]interface{}{
+		"collection_id": uuid.UUID(updated.ID.Bytes).String(),
+		"rule":          rule,
+		"is_smart":      h.collectionService.IsSmartCollection(updated.AutoAssignRules),
+	})
+}
+
+// UpdateRule handles PUT /api/collections/:id/rules/:ruleId — currently
+// the enabled toggle; the payload may only carry {"enabled": bool}.
+func (h *CollectionHandler) UpdateRule(c *echo.Context) error {
+	collectionID, err := uuid.Parse(c.Param("id"))
+	if err != nil {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
+	}
+	ruleID := c.Param("ruleId")
+	if ruleID == "" {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "rule id required"})
+	}
+
+	var req struct {
+		Enabled *bool `json:"enabled" validate:"required"`
+	}
+	if err := c.Bind(&req); err != nil {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
+	}
+	if err := c.Validate(&req); err != nil {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
+	}
+
+	updated, err := h.collectionService.SetRuleEnabled(c.Request().Context(), collectionID, ruleID, *req.Enabled)
+	if err != nil {
+		if strings.Contains(err.Error(), "rule not found") {
+			return c.JSON(http.StatusNotFound, map[string]string{"error": err.Error()})
+		}
+		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
+	}
+
+	return c.JSON(http.StatusOK, map[string]interface{}{
+		"collection_id": uuid.UUID(updated.ID.Bytes).String(),
+		"is_smart":      h.collectionService.IsSmartCollection(updated.AutoAssignRules),
+	})
+}
+
+// RemoveRule handles DELETE /api/collections/:id/rules/:ruleId.
+func (h *CollectionHandler) RemoveRule(c *echo.Context) error {
+	collectionID, err := uuid.Parse(c.Param("id"))
+	if err != nil {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
+	}
+	ruleID := c.Param("ruleId")
+	if ruleID == "" {
+		return c.JSON(http.StatusBadRequest, map[string]string{"error": "rule id required"})
+	}
+
+	updated, err := h.collectionService.RemoveRule(c.Request().Context(), collectionID, ruleID)
+	if err != nil {
+		if strings.Contains(err.Error(), "rule not found") {
+			return c.JSON(http.StatusNotFound, map[string]string{"error": err.Error()})
+		}
+		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
+	}
+
+	return c.JSON(http.StatusOK, map[string]interface{}{
+		"collection_id": uuid.UUID(updated.ID.Bytes).String(),
+		"is_smart":      h.collectionService.IsSmartCollection(updated.AutoAssignRules),
+	})
+}
+
 type TestRulesRequest struct {
 	Rules []map[string]interface{} `json:"rules" validate:"required"`
 }
@@ -748,16 +974,32 @@ func (h *CollectionHandler) TestRules(c *echo.Context) error {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
 	}
 
-	mediaItems, err := h.db.ListMediaItems(c.Request().Context(), database.ListMediaItemsParams{
-		Limit:  1000,
-		Offset: 0,
+	// Candidates mirror what smart collections actually evaluate against:
+	// the requester's visible libraries and live items only — the preview
+	// must not promise matches the live render will never produce.
+	visibleIDs, err := h.userVisibleLibraryIDs(c)
+	if err != nil {
+		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
+	}
+	var visibleArg []pgtype.UUID
+	if len(visibleIDs) > 0 {
+		visibleArg = visibleIDs
+	}
+	mediaItems, err := h.db.GetVisibleLiveMediaForRules(c.Request().Context(), database.GetVisibleLiveMediaForRulesParams{
+		LibraryID:         pgtype.UUID{},
+		VisibleLibraryIds: visibleArg,
 	})
 	if err != nil {
 		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "failed to load media items"})
 	}
 
+	listRows := make([]database.ListMediaItemsRow, len(mediaItems))
+	for i, item := range mediaItems {
+		listRows[i] = mediaItemsToListMediaItemsRow(item)
+	}
+
 	var matches []BookMatch
-	for _, item := range mediaItems {
+	for _, item := range listRows {
 		matchReason := h.checkRulesAgainstBook(item, req.Rules)
 		if matchReason != "" {
 			author := ""
@@ -886,6 +1128,16 @@ func (h *CollectionHandler) HandleBulkAddBooks(c *echo.Context) error {
 		return c.JSON(http.StatusBadRequest, map[string]string{"error": "operations required"})
 	}
 
+	// Smart collections are rejected up front per operation so the
+	// caller sees a clean, actionable error instead of silent no-ops.
+	for _, op := range req.Operations {
+		if colUUID, err := uuid.Parse(op.CollectionID); err == nil {
+			if guardErr := h.rejectSmartMutation(c, colUUID); guardErr != nil {
+				return guardErr
+			}
+		}
+	}
+
 	results := make([]map[string]interface{}, 0)
 	successCount := 0
 	failedCount := 0

internal/router/collections.go

@@ -22,6 +22,12 @@ func registerCollectionsRoutes(cfg *Config) {
 	collections.POST("/test-rules", cfg.CollectionHandler.TestRules)
 	collections.POST("/preview", cfg.CollectionHandler.PreviewCollection)
 
+	// Smart collection rule CRUD (the rules builder persists through
+	// these; type follows rules presence — first rule = smart).
+	collections.POST("/:id/rules", cfg.CollectionHandler.AddRule)
+	collections.PUT("/:id/rules/:ruleId", cfg.CollectionHandler.UpdateRule)
+	collections.DELETE("/:id/rules/:ruleId", cfg.CollectionHandler.RemoveRule)
+
 	// Device shelf mapping routes
 	deviceCollections := protected.Group("/devices/:id/collections")
 	deviceCollections.GET("", cfg.CollectionHandler.GetDeviceMappings)

internal/router/frontend.go

@@ -19,8 +19,10 @@ import (
 	"bookhoard/internal/utils"
 	"bookhoard/internal/version"
 	"bookhoard/templates"
+	"errors"
 
 	"github.com/golang-jwt/jwt/v5"
+	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgtype"
 	"github.com/labstack/echo/v5"
 
@@ -496,14 +498,56 @@ func registerFrontendRoutes(cfg *Config) {
 			errorMsg = "Error loading collections"
 		}
 
+		// Live per-card counts: smart collections are rule-matched at
+		// render against the requesting user's visible libraries; static
+		// ones count their stored links. Library filter applies when a
+		// specific library is selected.
+		libRes := resolveLibrary(c, cfg, user.ID)
+		var libScope pgtype.UUID
+		if !libRes.IsAll {
+			if parsed, parseErr := uuid.Parse(libRes.LibraryID); parseErr == nil {
+				libScope = pgtype.UUID{Bytes: parsed, Valid: true}
+			}
+		}
+		visibleIDs, visErr := cfg.CollectionHandler.UserVisibleLibraryIDs(c)
+		if visErr != nil {
+			log.Printf("UserVisibleLibraryIDs failed: %v", visErr)
+			visibleIDs = nil
+		}
+
 		colData := make([]templates.CollectionData, len(collections))
+		colService := cfg.CollectionHandler.CollectionService()
 		for i, col := range collections {
+			isSmart := colService.IsSmartCollection(col.AutoAssignRules)
+			bookCount := 0
+			if isSmart {
+				matches, evalErr := colService.EvaluateSmartCollection(c.Request().Context(),
+					colService.ParseRules(col.AutoAssignRules), services.SmartEvalOptions{
+						LibraryID:  libScope,
+						VisibleIDs: visibleIDs,
+					})
+				if evalErr == nil {
+					bookCount = len(matches)
+				}
+			} else {
+				count, countErr := cfg.Queries.CountCollectionLiveItems(c.Request().Context(), database.CountCollectionLiveItemsParams{
+					CollectionID: pgtype.UUID{Bytes: col.ID.Bytes, Valid: true},
+					LibraryID:    libScope,
+				})
+				if countErr == nil {
+					bookCount = int(count)
+				}
+			}
+
 			colData[i] = templates.CollectionData{
 				ID:          uuid.UUID(col.ID.Bytes).String(),
 				Name:        col.Name,
 				Description: getText(col.Description),
 				Color:       getText(col.Color),
 				Icon:        getText(col.Icon),
+				IsSystem:    col.IsSystemCollection.Bool,
+				IsSmart:     isSmart,
+				BookCount:   bookCount,
 			}
 		}
 
@@ -572,6 +616,47 @@ func registerFrontendRoutes(cfg *Config) {
 		return c.HTML(http.StatusOK, buf.String())
 	})
 
+	// Smart collection rules builder page (the smart editor). User
+	// collections only: system sections keep their hardwired queries.
+	frontendProtected.GET("/collections/:id/rules", func(c *echo.Context) error {
+		user, err := getTemplateUserWithTheme(c, cfg)
+		if err != nil {
+			return renderErrorPage(c, "Error loading user", "user_load_error")
+		}
+		collectionID := c.Param("id")
+		collUUID, err := uuid.Parse(collectionID)
+		if err != nil {
+			return renderErrorPage(c, "Invalid collection ID", "invalid_id")
+		}
+		collection, err := cfg.Queries.GetCollection(c.Request().Context(), pgtype.UUID{Bytes: collUUID, Valid: true})
+		if err != nil {
+			if errors.Is(err, pgx.ErrNoRows) {
+				return renderErrorPage(c, "Collection not found", "not_found")
+			}
+			return renderErrorPage(c, "Error loading collection", "collection_load_error")
+		}
+		if collection.IsSystemCollection.Bool {
+			return renderErrorPage(c, "System collections cannot have rules", "not_allowed")
+		}
+
+		colData := templates.CollectionData{
+			ID:          collectionID,
+			Name:        collection.Name,
+			Description: getText(collection.Description),
+			Color:       getText(collection.Color),
+			Icon:        getText(collection.Icon),
+			IsSystem:    collection.IsSystemCollection.Bool,
+			IsSmart:     cfg.CollectionHandler.CollectionService().IsSmartCollection(collection.AutoAssignRules),
+		}
+
+		var buf bytes.Buffer
+		err = templates.CollectionRules(user, colData).Render(c.Request().Context(), &buf)
+		if err != nil {
+			return err
+		}
+		return c.HTML(http.StatusOK, buf.String())
+	})
+
 	// Collection detail page (works for both system and user collections)
 	frontendProtected.GET("/collections/:id", func(c *echo.Context) error {
 		user, err := getTemplateUserWithTheme(c, cfg)
@@ -599,7 +684,44 @@ func registerFrontendRoutes(cfg *Config) {
 		libRes := resolveLibrary(c, cfg, user.ID)
 		libraryID := libRes.LibraryID
 
-		if collection.QueryType.Valid && collection.QueryType.String != "" {
+		var libScope pgtype.UUID
+		if !libRes.IsAll {
+			if parsed, parseErr := uuid.Parse(libraryID); parseErr == nil {
+				libScope = pgtype.UUID{Bytes: parsed, Valid: true}
+			}
+		}
+		colService := cfg.CollectionHandler.CollectionService()
+		isSmart := colService.IsSmartCollection(collection.AutoAssignRules)
+
+		visibleIDs, visErr := cfg.CollectionHandler.UserVisibleLibraryIDs(c)
+		if visErr != nil {
+			log.Printf("UserVisibleLibraryIDs failed: %v", visErr)
+			visibleIDs = nil
+		}
+
+		if isSmart {
+			// Smart (dynamic) collection: membership is evaluated live —
+			// visible libraries, live items only, any enabled rule matches.
+			matches, evalErr := colService.EvaluateSmartCollection(c.Request().Context(),
+				colService.ParseRules(collection.AutoAssignRules), services.SmartEvalOptions{
+					LibraryID:  libScope,
+					VisibleIDs: visibleIDs,
+				})
+			if evalErr != nil {
+				return renderErrorPage(c, "Error loading books", "books_load_error")
+			}
+			bookCards := make([]handlers.BookInfo, 0, len(matches))
+			for _, item := range matches {
+				itemUUID, _ := uuid.FromBytes(item.ID.Bytes[0:16])
+				bookCards = append(bookCards, handlers.BookInfo{
+					MediaItemID:    itemUUID.String(),
+					Title:          item.Title,
+					Author:         getText(item.Author),
+					CoverImagePath: utils.ResolveMediaURL(item.LibraryID, item.CoverImagePath),
+				})
+			}
+			books = bookCards
+		} else if collection.IsSystemCollection.Bool && collection.QueryType.Valid && collection.QueryType.String != "" && collection.QueryType.String != "filter" {
 			dashboardSvc := services.NewDashboardService(cfg.Queries)
 			sections, secErr := dashboardSvc.GetDashboardSections(c.Request().Context(), userUUID, libRes.LibUUID, 1000, []string{}, []string{})
 			if secErr != nil {
@@ -684,6 +806,8 @@ func registerFrontendRoutes(cfg *Config) {
 			Color:       collection.Color.String,
 			Icon:        collection.Icon.String,
 			IsSystem:    collection.IsSystemCollection.Bool,
+			IsSmart:     isSmart,
+			BookCount:   len(books),
 		}
 
 		var buf bytes.Buffer

internal/services/collection_service.go

@@ -24,8 +24,30 @@ type Rule struct {
 	Operator string `json:"operator"` // "equals", "contains", "starts_with", "ends_with", "greater_than", "less_than"
 	Value    string `json:"value"`
 	Priority int    `json:"priority"` // 1-10, higher values take precedence
+	// Enabled gates the rule in the LIVE evaluation used by smart
+	// collections; absent (JSON omitempty) means enabled — rules written
+	// before the field existed keep matching.
+	Enabled *bool `json:"enabled,omitempty"`
 }
 
+// Known rule fields and operators — the rules builder UI and the
+// persisted JSONB documents must agree with this vocabulary.
+var ruleFields = map[string]bool{
+	"genre": true, "series": true, "author": true, "language": true,
+	"publisher": true, "copyright_year": true, "tags": true,
+}
+
+var ruleOperators = map[string]bool{
+	"equals": true, "not_equals": true, "contains": true, "not_contains": true,
+	"starts_with": true, "ends_with": true, "greater_than": true, "less_than": true,
+}
+
+// RuleValidationError reports a rule payload the evaluator could never
+// honor (unknown field/operator, empty value).
+type RuleValidationError struct{ Msg string }
+
+func (e *RuleValidationError) Error() string { return e.Msg }
+
 // RuleEvaluation represents the result of evaluating a rule
 type RuleEvaluation struct {
 	RuleID     string  `json:"rule_id"`
@@ -244,6 +266,248 @@ func (s *CollectionService) GetBookCollections(ctx context.Context, mediaItemID
 	return collections, nil
 }
 
+// ParseRules decodes a collection's auto_assign_rules JSONB into typed
+// rules. "null", empty, and malformed docs mean "no rules".
+func (s *CollectionService) ParseRules(raw []byte) []Rule {
+	if len(raw) == 0 {
+		return nil
+	}
+	var rules []Rule
+	if err := json.Unmarshal(raw, &rules); err != nil {
+		return nil
+	}
+	return rules
+}
+
+// IsSmartCollection derives the collection type: a non-empty ruleset
+// makes it SMART (live-matched), an empty/absent ruleset makes it STATIC
+// (stored collection_items links).
+func (s *CollectionService) IsSmartCollection(raw []byte) bool {
+	return len(s.ParseRules(raw)) > 0
+}
+
+// EnabledRules filters a ruleset down to the rules that participate in
+// live evaluation (absent enabled = enabled for backward compatibility).
+func (s *CollectionService) EnabledRules(rules []Rule) []Rule {
+	enabled := make([]Rule, 0, len(rules))
+	for _, rule := range rules {
+		if rule.Enabled == nil || *rule.Enabled {
+			enabled = append(enabled, rule)
+		}
+	}
+	return enabled
+}
+
+// validateRule checks a rule payload the evaluator will have to honor.
+func (s *CollectionService) validateRule(rule Rule) error {
+	if !ruleFields[rule.Field] {
+		return &RuleValidationError{Msg: "unknown rule field: " + rule.Field}
+	}
+	if !ruleOperators[rule.Operator] {
+		return &RuleValidationError{Msg: "unknown rule operator: " + rule.Operator}
+	}
+	if strings.TrimSpace(rule.Value) == "" {
+		return &RuleValidationError{Msg: "rule value is required"}
+	}
+	if rule.Priority < 0 || rule.Priority > 10 {
+		return &RuleValidationError{Msg: "priority must be between 0 and 10"}
+	}
+	return nil
+}
+
+// AddRule appends a rule to the collection's ruleset, generating an id
+// when the caller did not supply one. Adding the first rule CONVERTS a
+// static collection to smart (type is derived from rules presence).
+func (s *CollectionService) AddRule(ctx context.Context, collectionID uuid.UUID, rule Rule) (database.Collections, Rule, error) {
+	if err := s.validateRule(rule); err != nil {
+		return database.Collections{}, Rule{}, err
+	}
+
+	collection, err := s.GetCollection(ctx, collectionID)
+	if err != nil {
+		return database.Collections{}, Rule{}, err
+	}
+
+	rules := s.ParseRules(collection.AutoAssignRules)
+	if rule.ID == "" {
+		rule.ID = uuid.NewString()
+	}
+	rules = append(rules, rule)
+
+	rulesJSON, marshalErr := json.Marshal(rules)
+	if marshalErr != nil {
+		return database.Collections{}, Rule{}, fmt.Errorf("failed to marshal rules: %w", marshalErr)
+	}
+
+	updated, err := s.db.UpdateCollectionRulesJSON(ctx, database.UpdateCollectionRulesJSONParams{
+			ID:              pgtype.UUID{Bytes: collectionID, Valid: true},
+			AutoAssignRules: rulesJSON,
+		})
+	if err != nil {
+		return database.Collections{}, Rule{}, fmt.Errorf("failed to save rules: %w", err)
+	}
+	return updated, rule, nil
+}
+
+// SetRuleEnabled flips a single rule's enabled flag in place.
+func (s *CollectionService) SetRuleEnabled(ctx context.Context, collectionID uuid.UUID, ruleID string, enabled bool) (database.Collections, error) {
+	collection, err := s.GetCollection(ctx, collectionID)
+	if err != nil {
+		return database.Collections{}, err
+	}
+	rules := s.ParseRules(collection.AutoAssignRules)
+	found := false
+	for i := range rules {
+		if rules[i].ID == ruleID {
+			rules[i].Enabled = &enabled
+			found = true
+			break
+		}
+	}
+	if !found {
+		return database.Collections{}, fmt.Errorf("rule not found: %s", ruleID)
+	}
+
+	rulesJSON, marshalErr := json.Marshal(rules)
+	if marshalErr != nil {
+		return database.Collections{}, fmt.Errorf("failed to marshal rules: %w", marshalErr)
+	}
+
+	updated, err := s.db.UpdateCollectionRulesJSON(ctx, database.UpdateCollectionRulesJSONParams{
+			ID:              pgtype.UUID{Bytes: collectionID, Valid: true},
+			AutoAssignRules: rulesJSON,
+		})
+	if err != nil {
+		return database.Collections{}, fmt.Errorf("failed to save rules: %w", err)
+	}
+	return updated, nil
+}
+
+// RemoveRule deletes a single rule from the ruleset. Removing the LAST
+// rule converts the collection back to static (type is derived).
+func (s *CollectionService) RemoveRule(ctx context.Context, collectionID uuid.UUID, ruleID string) (database.Collections, error) {
+	collection, err := s.GetCollection(ctx, collectionID)
+	if err != nil {
+		return database.Collections{}, err
+	}
+	rules := s.ParseRules(collection.AutoAssignRules)
+	kept := make([]Rule, 0, len(rules))
+	found := false
+	for _, rule := range rules {
+		if rule.ID == ruleID {
+			found = true
+			continue
+		}
+		kept = append(kept, rule)
+	}
+	if !found {
+		return database.Collections{}, fmt.Errorf("rule not found: %s", ruleID)
+	}
+
+	rulesJSON, marshalErr := json.Marshal(kept)
+	if marshalErr != nil {
+		return database.Collections{}, fmt.Errorf("failed to marshal rules: %w", marshalErr)
+	}
+
+	updated, err := s.db.UpdateCollectionRulesJSON(ctx, database.UpdateCollectionRulesJSONParams{
+			ID:              pgtype.UUID{Bytes: collectionID, Valid: true},
+			AutoAssignRules: rulesJSON,
+		})
+	if err != nil {
+		return database.Collections{}, fmt.Errorf("failed to save rules: %w", err)
+	}
+	return updated, nil
+}
+
+// SmartEvalOptions scopes a smart collection's live evaluation.
+type SmartEvalOptions struct {
+	// LibraryID, when valid, restricts matching to one library (the
+	// detail page's library switcher).
+	LibraryID pgtype.UUID
+	// VisibleIDs is the requesting user's visible-library set (family
+	// lens). Empty means no visible-library filter.
+	VisibleIDs []pgtype.UUID
+}
+
+// EvaluateSmartCollection resolves a smart collection's membership LIVE:
+// every visible live book matched by at least one enabled rule is in.
+// No stored links are consulted — "truly dynamic," always current.
+func (s *CollectionService) EvaluateSmartCollection(ctx context.Context, rules []Rule, opts SmartEvalOptions) ([]database.MediaItems, error) {
+	enabled := s.EnabledRules(rules)
+	if len(enabled) == 0 {
+		return []database.MediaItems{}, nil
+	}
+
+	var visibleArg []pgtype.UUID
+	if len(opts.VisibleIDs) > 0 {
+		visibleArg = opts.VisibleIDs
+	}
+	items, err := s.db.GetVisibleLiveMediaForRules(ctx, database.GetVisibleLiveMediaForRulesParams{
+		LibraryID:         opts.LibraryID,
+		VisibleLibraryIds: visibleArg,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to load candidate books: %w", err)
+	}
+
+	matches := make([]database.MediaItems, 0, len(items))
+	for _, item := range items {
+		if s.mediaItemMatchesAnyRule(item, enabled) {
+			matches = append(matches, item)
+		}
+	}
+	return matches, nil
+}
+
+func (s *CollectionService) mediaItemMatchesAnyRule(item database.MediaItems, rules []Rule) bool {
+	for _, rule := range rules {
+		if s.mediaItemMatchesRule(item, rule) {
+			return true
+		}
+	}
+	return false
+}
+
+func (s *CollectionService) mediaItemMatchesRule(item database.MediaItems, rule Rule) bool {
+	if rule.Enabled != nil && !*rule.Enabled {
+		return false
+	}
+
+	var fieldValue string
+	switch rule.Field {
+	case "genre":
+		if item.Genre.Valid {
+			fieldValue = item.Genre.String
+		}
+	case "series":
+		if item.Series.Valid {
+			fieldValue = item.Series.String
+		}
+	case "author":
+		if item.Author.Valid {
+			fieldValue = item.Author.String
+		}
+	case "language":
+		if item.Language.Valid {
+			fieldValue = item.Language.String
+		}
+	case "publisher":
+		if item.Publisher.Valid {
+			fieldValue = item.Publisher.String
+		}
+	case "copyright_year":
+		if item.CopyrightYear.Valid {
+			fieldValue = fmt.Sprintf("%d", item.CopyrightYear.Int32)
+		}
+	case "tags":
+		if len(item.Tags) > 0 {
+			fieldValue = strings.Join(item.Tags, ", ")
+		}
+	}
+
+	return s.evaluateRule(fieldValue, rule.Operator, rule.Value)
+}
+
 // EvaluateRules evaluates auto-assign rules for a media item
 func (s *CollectionService) EvaluateRules(mediaItem database.ListMediaItemsRow, rules []Rule) []RuleEvaluation {
 	var evaluations []RuleEvaluation
@@ -260,6 +524,11 @@ func (s *CollectionService) EvaluateRules(mediaItem database.ListMediaItemsRow,
 	}
 
 	for _, rule := range sortedRules {
+		// Disabled rules never match (kept for context in the UI only).
+		if rule.Enabled != nil && !*rule.Enabled {
+			evaluations = append(evaluations, RuleEvaluation{RuleID: rule.ID, Matches: false})
+			continue
+		}
 		eval := RuleEvaluation{
 			RuleID:  rule.ID,
 			Matches: false,