diff --git a/backend/scripts/clear_thumbnail_cache.py b/backend/scripts/clear_thumbnail_cache.py
index a44c9df..a566df8 100644
--- a/backend/scripts/clear_thumbnail_cache.py
+++ b/backend/scripts/clear_thumbnail_cache.py
@@ -110,20 +110,26 @@ async def clear_thumbnail_for_resource(resource_id: str) -> bool:
     return deleted > 0
 
 
+async def clear_thumbnails_for_resources(resource_ids: list[str]) -> int:
+    """Clear thumbnail caches for all resources within one event loop."""
+    cleared = 0
+    for resource_id in resource_ids:
+        try:
+            if await clear_thumbnail_for_resource(resource_id):
+                cleared += 1
+        except Exception as exc:
+            logger.error(f"Failed for {resource_id}: {exc}")
+            raise
+    return cleared
+
+
 def main():
     if len(sys.argv) < 2:
         print("Usage: python scripts/clear_thumbnail_cache.py RESOURCE_ID [RESOURCE_ID ...]")
         sys.exit(1)
 
     resource_ids = sys.argv[1:]
-    cleared = 0
-    for rid in resource_ids:
-        try:
-            if asyncio.run(clear_thumbnail_for_resource(rid)):
-                cleared += 1
-        except Exception as e:
-            logger.error(f"Failed for {rid}: {e}")
-            raise
+    cleared = asyncio.run(clear_thumbnails_for_resources(resource_ids))
 
     print(f"Cleared cache for {cleared}/{len(resource_ids)} resource(s)")
 
diff --git a/backend/tests/scripts/test_clear_thumbnail_cache.py b/backend/tests/scripts/test_clear_thumbnail_cache.py
new file mode 100644
index 0000000..062cc8f
--- /dev/null
+++ b/backend/tests/scripts/test_clear_thumbnail_cache.py
@@ -0,0 +1,49 @@
+import asyncio
+from unittest.mock import patch
+
+import pytest
+
+import scripts.clear_thumbnail_cache as clear_thumbnail_cache
+
+
+@pytest.mark.asyncio
+async def test_clear_multiple_resources_uses_one_event_loop():
+    calls: list[tuple[str, asyncio.AbstractEventLoop]] = []
+
+    async def fake_clear(resource_id: str) -> bool:
+        calls.append((resource_id, asyncio.get_running_loop()))
+        return resource_id != "unr-missing"
+
+    with patch.object(
+        clear_thumbnail_cache,
+        "clear_thumbnail_for_resource",
+        side_effect=fake_clear,
+    ):
+        cleared = await clear_thumbnail_cache.clear_thumbnails_for_resources(
+            ["unr-one", "unr-missing", "unr-two"]
+        )
+
+    assert cleared == 2
+    assert [resource_id for resource_id, _loop in calls] == [
+        "unr-one",
+        "unr-missing",
+        "unr-two",
+    ]
+    assert len({id(loop) for _resource_id, loop in calls}) == 1
+
+
+def test_main_runs_one_batch_and_prints_summary(capsys):
+    with (
+        patch.object(
+            clear_thumbnail_cache.sys,
+            "argv",
+            ["clear_thumbnail_cache.py", "unr-one", "unr-two"],
+        ),
+        patch.object(clear_thumbnail_cache.asyncio, "run", return_value=1) as mock_run,
+    ):
+        clear_thumbnail_cache.main()
+
+    batch_coroutine = mock_run.call_args.args[0]
+    batch_coroutine.close()
+    mock_run.assert_called_once()
+    assert "Cleared cache for 1/2 resource(s)" in capsys.readouterr().out