fix(catalog): preserve normalized TMDB ownership

internal/catalog/provider_id_repo.go

@@ -118,14 +118,34 @@ func (r *ProviderIDRepository) AttachTMDBID(ctx context.Context, contentID, item
 	}
 
 	var existingOwnerContentID string
-	err = tx.QueryRow(ctx, `
+	ownerQuery := `
 		SELECT content_id
 		FROM media_items
-		WHERE type = $1
-		  AND tmdb_id = $2
+		WHERE tmdb_id >= $2
+		  AND type = $1
 		  AND content_id <> $3
+		  AND (tmdb_id = $2 OR tmdb_id LIKE $2 || '-%')
 		LIMIT 1
-	`, itemType, tmdbText, contentID).Scan(&existingOwnerContentID)
+	`
+	ownerArgs := []any{itemType, tmdbText, contentID}
+	// Bound ordinary slug candidates with the existing tmdb_id index. A run of
+	// nines has no same-width numeric successor, so that rare boundary uses the
+	// lower-bounded predicate above rather than an empty lexical range.
+	tmdbUpper := strconv.FormatUint(uint64(tmdbID)+1, 10)
+	if len(tmdbUpper) == len(tmdbText) {
+		ownerQuery = `
+			SELECT content_id
+			FROM media_items
+			WHERE tmdb_id >= $1
+			  AND tmdb_id < $2
+			  AND type = $3
+			  AND content_id <> $4
+			  AND (tmdb_id = $1 OR tmdb_id LIKE $1 || '-%')
+			LIMIT 1
+		`
+		ownerArgs = []any{tmdbText, tmdbUpper, itemType, contentID}
+	}
+	err = tx.QueryRow(ctx, ownerQuery, ownerArgs...).Scan(&existingOwnerContentID)
 	if err != nil && !errors.Is(err, pgx.ErrNoRows) {
 		return fmt.Errorf("checking tmdb id owner: %w", err)
 	}

internal/catalog/provider_id_tmdb_match_test.go

@@ -1,6 +1,15 @@
 package catalog
 
-import "testing"
+import (
+	"context"
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
 
 // Real values seen rejected in production: media_items.tmdb_id held TMDB's
 // "id-slug" URL form while the presence lookup attached the bare numeric id, so
@@ -39,3 +48,52 @@ func TestNormalizeTMDBIDLeavesNonIdentifiersAlone(t *testing.T) {
 		t.Errorf("normalizeTMDBID(%q) = %q", "", got)
 	}
 }
+
+func TestAttachTMDBIDRejectsEquivalentSlugOwner(t *testing.T) {
+	dsn := strings.TrimSpace(os.Getenv("SILO_TEST_DATABASE_URL"))
+	if dsn == "" {
+		t.Skip("SILO_TEST_DATABASE_URL is not set")
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+	pool, err := pgxpool.New(ctx, dsn)
+	if err != nil {
+		t.Fatalf("connect to test database: %v", err)
+	}
+	t.Cleanup(pool.Close)
+
+	suffix := time.Now().UnixNano()
+	// A run of nines guards the lexical range bound used by the owner lookup:
+	// incrementing the numeric id would produce a shorter, invalid upper bound.
+	tmdbID := 999_999_999
+	ownerContentID := fmt.Sprintf("test-tmdb-slug-owner-%d", suffix)
+	targetContentID := fmt.Sprintf("test-tmdb-slug-target-%d", suffix)
+	if _, err := pool.Exec(ctx, `
+		INSERT INTO media_items (content_id, type, title, tmdb_id)
+		VALUES ($1, 'series', 'TMDB slug owner test', $3),
+		       ($2, 'series', 'TMDB slug target test', '')
+	`, ownerContentID, targetContentID, fmt.Sprintf("%d-some-title", tmdbID)); err != nil {
+		t.Fatalf("insert test media items: %v", err)
+	}
+	t.Cleanup(func() {
+		cleanupCtx, cleanupCancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cleanupCancel()
+		if _, err := pool.Exec(cleanupCtx, `DELETE FROM media_items WHERE content_id = ANY($1)`, []string{ownerContentID, targetContentID}); err != nil {
+			t.Errorf("clean up test media items: %v", err)
+		}
+	})
+
+	err = NewProviderIDRepository(pool).AttachTMDBID(ctx, targetContentID, "series", tmdbID)
+	if err == nil || !strings.Contains(err.Error(), "already belongs to content_id") {
+		t.Fatalf("AttachTMDBID() error = %v, want existing-owner conflict", err)
+	}
+
+	var targetTMDBID string
+	if err := pool.QueryRow(ctx, `SELECT tmdb_id FROM media_items WHERE content_id = $1`, targetContentID).Scan(&targetTMDBID); err != nil {
+		t.Fatalf("load target tmdb id: %v", err)
+	}
+	if targetTMDBID != "" {
+		t.Fatalf("target tmdb_id = %q, want unchanged", targetTMDBID)
+	}
+}