diff --git a/backend/app/services/download_service.py b/backend/app/services/download_service.py
index 2a8778a..b62dcd0 100644
--- a/backend/app/services/download_service.py
+++ b/backend/app/services/download_service.py
@@ -20,7 +20,8 @@ from typing import Any
 
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
-from sqlalchemy.orm import Session as SyncSession, joinedload
+from sqlalchemy.orm import Session as SyncSession
+from sqlalchemy.orm import joinedload
 
 from ..models import Artist, DownloadEvent, Source
 from .credential_service import CredentialService
@@ -217,7 +218,10 @@ class DownloadService:
             if path_str in (dl_result.quarantined_paths or []):
                 continue
             path = Path(path_str)
-            if not path.exists():
+            # Sync stdlib filesystem ops are intentional here: this orchestrator
+            # runs under `asyncio.run` inside a Celery task — no other awaitables
+            # compete for the loop. ASYNC240 suppressed below.
+            if not path.exists():  # noqa: ASYNC240
                 continue
 
             def _attach(p=path):
@@ -230,7 +234,7 @@ class DownloadService:
             if result.status in ("imported", "superseded"):
                 import_summary["attached"] += 1
                 try:
-                    bytes_downloaded += path.stat().st_size
+                    bytes_downloaded += path.stat().st_size  # noqa: ASYNC240
                 except OSError:
                     pass
             elif result.status == "skipped" and result.skip_reason and result.skip_reason.value in (
@@ -238,7 +242,7 @@ class DownloadService:
             ):
                 import_summary["skipped"] += 1
                 try:
-                    path.unlink(missing_ok=True)
+                    path.unlink(missing_ok=True)  # noqa: ASYNC240
                 except OSError:
                     pass
             else:
diff --git a/backend/app/services/file_validator.py b/backend/app/services/file_validator.py
index 791b142..ca6e40f 100644
--- a/backend/app/services/file_validator.py
+++ b/backend/app/services/file_validator.py
@@ -14,7 +14,6 @@ from __future__ import annotations
 from dataclasses import dataclass
 from pathlib import Path
 
-
 JPEG_HEAD = b"\xff\xd8\xff"
 JPEG_TAIL = b"\xff\xd9"
 
diff --git a/backend/app/services/gallery_dl.py b/backend/app/services/gallery_dl.py
index eb37a2f..5e9b17f 100644
--- a/backend/app/services/gallery_dl.py
+++ b/backend/app/services/gallery_dl.py
@@ -19,7 +19,7 @@ import tempfile
 import time
 from dataclasses import dataclass, field
 from datetime import UTC, datetime
-from enum import Enum
+from enum import StrEnum
 from pathlib import Path
 
 from .file_validator import is_validatable, validate_file
@@ -27,7 +27,7 @@ from .file_validator import is_validatable, validate_file
 log = logging.getLogger(__name__)
 
 
-class ErrorType(str, Enum):
+class ErrorType(StrEnum):
     AUTH_ERROR = "auth_error"
     RATE_LIMITED = "rate_limited"
     NOT_FOUND = "not_found"
@@ -655,6 +655,6 @@ class GalleryDLService:
             )
         finally:
             try:
-                Path(temp_config_path).unlink()
+                Path(temp_config_path).unlink()  # noqa: ASYNC240
             except Exception:
                 pass