diff --git a/backend/alembic/versions/063_hartomat_rebrand_backfill.py b/backend/alembic/versions/063_hartomat_rebrand_backfill.py
index d653c7d..76d0a66 100644
--- a/backend/alembic/versions/063_hartomat_rebrand_backfill.py
+++ b/backend/alembic/versions/063_hartomat_rebrand_backfill.py
@@ -1,13 +1,13 @@
 """Backfill persisted Schaeffler branding to HartOMat.
 
 Revision ID: 063
-Revises: 062
+Revises: a68e8c6fb61b
 """
 from alembic import op
 import sqlalchemy as sa
 
 revision = "063"
-down_revision = "062"
+down_revision = "a68e8c6fb61b"
 branch_labels = None
 depends_on = None
 
diff --git a/backend/app/utils/seed_templates.py b/backend/app/utils/seed_templates.py
index f784022..4eafce3 100644
--- a/backend/app/utils/seed_templates.py
+++ b/backend/app/utils/seed_templates.py
@@ -134,6 +134,7 @@ TEMPLATES = [
 
 
 async def seed(db_url: str, admin_email: str = "admin@hartomat.com", admin_password: str = "Admin1234!"):
+    from app.domains.tenants.models import Tenant
     from app.models.template import Template
     from app.models.user import User, UserRole
     from app.utils.auth import hash_password
@@ -142,6 +143,17 @@ async def seed(db_url: str, admin_email: str = "admin@hartomat.com", admin_passw
     session_factory = async_sessionmaker(engine, expire_on_commit=False)
 
     async with session_factory() as session:
+        # Ensure the default single-tenant setup exists before seeding tenant-scoped data.
+        tenant_result = await session.execute(select(Tenant).where(Tenant.slug == "hartomat"))
+        default_tenant = tenant_result.scalar_one_or_none()
+        if not default_tenant:
+            default_tenant = Tenant(name="HartOMat", slug="hartomat", is_active=True)
+            session.add(default_tenant)
+            await session.flush()
+            print("  + Default tenant: hartomat")
+        else:
+            print("  ~ Default tenant already exists: hartomat")
+
         # Seed templates
         for tpl_data in TEMPLATES:
             result = await session.execute(
@@ -149,24 +161,32 @@ async def seed(db_url: str, admin_email: str = "admin@hartomat.com", admin_passw
             )
             existing = result.scalar_one_or_none()
             if not existing:
-                tpl = Template(**tpl_data)
+                tpl = Template(**tpl_data, tenant_id=default_tenant.id)
                 session.add(tpl)
                 print(f"  + Template: {tpl_data['category_key']}")
             else:
+                if existing.tenant_id is None:
+                    existing.tenant_id = default_tenant.id
+                    print(f"  * Backfilled template tenant: {tpl_data['category_key']}")
                 print(f"  ~ Template already exists: {tpl_data['category_key']}")
 
         # Seed admin user
         result = await session.execute(select(User).where(User.email == admin_email))
-        if not result.scalar_one_or_none():
+        existing_admin = result.scalar_one_or_none()
+        if not existing_admin:
             admin = User(
                 email=admin_email,
                 password_hash=hash_password(admin_password),
                 role=UserRole.global_admin,
                 full_name="HartOMat Admin",
+                tenant_id=default_tenant.id,
             )
             session.add(admin)
             print(f"  + Admin user: {admin_email}")
         else:
+            if existing_admin.tenant_id is None:
+                existing_admin.tenant_id = default_tenant.id
+                print(f"  * Backfilled admin tenant: {admin_email}")
             print(f"  ~ Admin user already exists: {admin_email}")
 
         await session.commit()
diff --git a/docker-compose.worker.yml b/docker-compose.worker.yml
index 102517d..5ee9c8b 100644
--- a/docker-compose.worker.yml
+++ b/docker-compose.worker.yml
@@ -1,3 +1,5 @@
+name: hartomat
+
 # External render-worker configuration.
 #
 # Use this compose file on remote machines (GPU nodes, NAS, cloud VMs) that
diff --git a/docker-compose.yml b/docker-compose.yml
index 7a2678c..bd0241e 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,3 +1,5 @@
+name: hartomat
+
 services:
   postgres:
     image: postgres:16-alpine