Name uploaded and downloaded files J-<id>.<ext>

Files added through the upload pipeline and Download to Library are
renamed to their J-ID right after indexing, so every new library file is
traceable by its identifier (scanned files keep their existing names).
index_file now returns the created location so callers can rename it;
the location record is updated to the new path.

backend/apps/library/management/commands/scan_files.py

@@ -67,7 +67,9 @@ class Command(BaseCommand):
                     continue
                 path = Path(root) / name
                 try:
-                    item, created_item, created_location = index_file(path, folder)
+                    item, created_item, _location, created_location = index_file(
+                        path, folder
+                    )
                 except OSError as exc:
                     skipped += 1
                     self.stderr.write(f"Skipped {path}: {exc}")

backend/apps/library/services.py

@@ -41,7 +41,7 @@ def compute_md5(path):
 def index_file(path, folder):
     """Index one file into MediaItem/MediaLocation.
 
-    Returns (item, created_item, created_location).
+    Returns (item, created_item, location, created_location).
     """
     path = Path(path)
     folder = Path(folder)
@@ -61,7 +61,25 @@ def index_file(path, folder):
             "mtime": stat.st_mtime,
         },
     )
-    return item, created_item, created_location
+    return item, created_item, location, created_location
+
+
+def rename_location_to_j_id(item, location):
+    """Name a freshly indexed copy J-<id>.<ext> inside its own folder."""
+    path = Path(location.path)
+    if not path.exists():
+        return location
+    if path.stem == f"J-{item.id}":
+        return location
+    target = unique_destination(path.parent, f"J-{item.id}{path.suffix}")
+    path.rename(target)
+    parent = Path(location.rel_path).parent
+    location.path = str(target)
+    location.rel_path = (
+        str(parent / target.name) if str(parent) != "." else target.name
+    )
+    location.save(update_fields=["path", "rel_path"])
+    return location
 
 
 def parse_tags(raw):

backend/apps/library/uploads.py

@@ -55,7 +55,8 @@ def complete_temp_upload(temp, download_url=None):
         except Exception:
             destination.unlink(missing_ok=True)
             raise
-        item, _, _ = services.index_file(destination, folder)
+        item, _, location, _ = services.index_file(destination, folder)
+        services.rename_location_to_j_id(item, location)
         if temp.file:
             temp.file.delete(save=False)
     else:
@@ -66,7 +67,8 @@ def complete_temp_upload(temp, download_url=None):
         )
         with temp.file.open("rb") as source, open(destination, "wb") as target:
             shutil.copyfileobj(source, target)
-        item, _, _ = services.index_file(destination, folder)
+        item, _, location, _ = services.index_file(destination, folder)
+        services.rename_location_to_j_id(item, location)
         temp.file.delete(save=False)
 
     temp.library_item = item

backend/apps/library/views.py

@@ -212,7 +212,7 @@ class DownloadToLibraryView(APIView):
         destination = services.unique_destination(folder, name)
         try:
             services.download_file(url, destination)
-            item, _, _ = services.index_file(destination, folder)
+            item, _, location, _ = services.index_file(destination, folder)
         except Exception as exc:  # noqa: BLE001 - report download failures
             destination.unlink(missing_ok=True)
             return Response(
@@ -239,6 +239,7 @@ class DownloadToLibraryView(APIView):
 
         if update_fields:
             item.save(update_fields=update_fields + ["updated_at"])
+        services.rename_location_to_j_id(item, location)
         return Response(
             MediaItemSerializer(item, context={"request": request}).data,
             status=status.HTTP_201_CREATED,