fix: the external-link worker reads the staging-file check from utils, not tasks.maintenance

Importing tasks.maintenance made every fetch path reach the membership
roster through its sync_memberships task, which test_gated_reason
forbids. is_temp_staging_file and its constants now live in
utils.staging, imported by both.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/app/tasks/external.py

@@ -32,8 +32,8 @@ from ..models import Artist, ExternalLink, ImageRecord, ImportSettings, Post, So
 from ..services.external_fetch import fetch_external
 from ..services.importer import Importer
 from ..services.thumbnailer import Thumbnailer
+from ..utils.staging import is_temp_staging_file
 from ._sync_engine import sync_session_factory as _sync_session_factory
-from .maintenance import is_temp_staging_file
 
 log = logging.getLogger(__name__)
 

backend/app/tasks/maintenance.py

@@ -24,6 +24,7 @@ from ..models import (
     TaskRun,
 )
 from ..utils.phash import compute_phash
+from ..utils.staging import is_temp_staging_file
 from ._sync_engine import get_sync_engine
 from ._sync_engine import sync_session_factory as _sync_session_factory
 
@@ -81,25 +82,12 @@ WIP_BACKFILL_PAGE = 500
 FFPROBE_TIMEOUT_SECONDS = 10
 TASK_RUN_KEEP_OK_SECONDS = 24 * 3600       # 24 h
 TASK_RUN_KEEP_FAILURE_SECONDS = 7 * 24 * 3600  # 7 days
-# Orphaned staging files: downloads/imports stage into <name>.part / <name>.partial
-# then os.replace() into place (importer / external_fetch / native_ingest_common /
-# attachment_store), so a kill mid-write leaves a discardable temp, never a corrupt
-# final. cleanup_orphaned_temp_files sweeps ones left behind; the min-age guard
-# keeps it from deleting an in-flight download's staging file mid-write.
+# Orphaned staging files (utils.staging): cleanup_orphaned_temp_files sweeps the
+# ones a killed write left behind; the min-age guard keeps it from deleting an
+# in-flight download's staging file mid-write.
 IMAGES_ROOT = Path("/images")
-TEMP_STAGING_SUFFIXES = (".part", ".partial")
-# megatools stages a Mega download as `.megatmp.<id>` in the target dir.
-TEMP_STAGING_PREFIXES = (".megatmp.",)
 ORPHAN_TEMP_MIN_AGE_HOURS = 6
 
-
-def is_temp_staging_file(path: Path) -> bool:
-    """True for a downloader's staging file: one that never becomes library
-    content under that name, so a stale one is safe to delete."""
-    return path.suffix in TEMP_STAGING_SUFFIXES or path.name.startswith(
-        TEMP_STAGING_PREFIXES
-    )
-
 # Audit 2026-06-02: per-entity recovery sweep thresholds. Each must be
 # > the entity's longest legitimate runtime (its task's time_limit + a
 # small buffer) so the sweep never flags in-flight work.

backend/app/utils/staging.py

@@ -0,0 +1,20 @@
+"""Downloader staging files.
+
+Downloads and imports write into a staging name and `os.replace()` it into
+place when the write completes (importer, external_fetch, native_ingest_common,
+attachment_store), so a write killed midway leaves a staging file, never a
+truncated final file. Any other file is complete.
+"""
+from pathlib import Path
+
+TEMP_STAGING_SUFFIXES = (".part", ".partial")
+# megatools stages a Mega download as `.megatmp.<id>` in the target dir.
+TEMP_STAGING_PREFIXES = (".megatmp.",)
+
+
+def is_temp_staging_file(path: Path) -> bool:
+    """True for a downloader's staging file: one that never becomes library
+    content under that name, so a stale one is safe to delete."""
+    return path.suffix in TEMP_STAGING_SUFFIXES or path.name.startswith(
+        TEMP_STAGING_PREFIXES
+    )