fix: stabilize Shopee cover replacement

tests/test_image_paths.py

@@ -0,0 +1,38 @@
+import os
+import sys
+import unittest
+from types import SimpleNamespace
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+
+from app import image_paths
+from app.config import make_slug
+
+
+class ImagePathTests(unittest.TestCase):
+    def test_task_image_path_uses_batch_slug_task_and_item(self):
+        root = os.path.abspath(os.path.join("tmp", "images"))
+        task = SimpleNamespace(id=42, batch_id=7, item_id="51100639510", alias="alias-a")
+        account = SimpleNamespace(slug="main_shop")
+
+        path = image_paths.task_image_path(root, task, account, "new")
+
+        self.assertEqual(
+            os.path.join(root, "7", "main_shop", "42_51100639510_new.jpg"),
+            path,
+        )
+
+    def test_task_image_path_falls_back_to_account_alias_slug(self):
+        root = os.path.abspath(os.path.join("tmp", "images"))
+        task = {"id": 5, "batch_id": 3, "item_id": "ITEM/1", "alias": "alias-a"}
+
+        path = image_paths.task_image_path(root, task, None, "old")
+
+        self.assertEqual(
+            os.path.join(root, "3", make_slug("alias-a"), "5_ITEM_1_old.jpg"),
+            path,
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()