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/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