diff --git a/py/services/metadata_sync_service.py b/py/services/metadata_sync_service.py
index 75d912f7..738f3b86 100644
--- a/py/services/metadata_sync_service.py
+++ b/py/services/metadata_sync_service.py
@@ -153,7 +153,12 @@ class MetadataSyncService:
         model_data: Dict[str, Any],
         update_cache_func: Callable[[str, str, Dict[str, Any]], Awaitable[bool]],
     ) -> tuple[bool, Optional[str]]:
-        """Fetch metadata for a model and update both disk and cache state."""
+        """Fetch metadata for a model and update both disk and cache state.
+
+        Callers should hydrate ``model_data`` via ``MetadataManager.hydrate_model_data``
+        before invoking this method so that the persisted payload retains all known
+        metadata fields.
+        """
 
         if not isinstance(model_data, dict):
             error = f"Invalid model_data type: {type(model_data)}"
@@ -177,8 +182,6 @@ class MetadataSyncService:
 
             civitai_metadata, error = await metadata_provider.get_model_by_hash(sha256)
 
-            await self._metadata_manager.hydrate_model_data(model_data)
-
             if not civitai_metadata:
                 if error == "Model not found":
                     model_data["from_civitai"] = False
diff --git a/tests/services/test_metadata_sync_service.py b/tests/services/test_metadata_sync_service.py
index 03af8d86..470259f6 100644
--- a/tests/services/test_metadata_sync_service.py
+++ b/tests/services/test_metadata_sync_service.py
@@ -124,6 +124,9 @@ async def test_fetch_and_update_model_success_updates_cache(tmp_path):
     }
     update_cache = AsyncMock(return_value=True)
 
+    await hydrate(model_data)
+    helpers.metadata_manager.hydrate_model_data.reset_mock()
+
     ok, error = await helpers.service.fetch_and_update_model(
         sha256="abc",
         file_path=str(model_path),
@@ -136,7 +139,7 @@ async def test_fetch_and_update_model_success_updates_cache(tmp_path):
     assert model_data["civitai_deleted"] is False
     assert "civitai" in model_data
 
-    helpers.metadata_manager.hydrate_model_data.assert_awaited_once()
+    helpers.metadata_manager.hydrate_model_data.assert_not_awaited()
     assert model_data["hydrated"] is True
 
     metadata_path = str(model_path.with_suffix(".metadata.json"))
@@ -167,6 +170,9 @@ async def test_fetch_and_update_model_handles_missing_remote_metadata(tmp_path):
         "file_path": str(model_path),
     }
 
+    await hydrate(model_data)
+    helpers.metadata_manager.hydrate_model_data.reset_mock()
+
     ok, error = await helpers.service.fetch_and_update_model(
         sha256="missing",
         file_path=str(model_path),
@@ -179,7 +185,7 @@ async def test_fetch_and_update_model_handles_missing_remote_metadata(tmp_path):
     assert model_data["from_civitai"] is False
     assert model_data["civitai_deleted"] is True
 
-    helpers.metadata_manager.hydrate_model_data.assert_awaited_once()
+    helpers.metadata_manager.hydrate_model_data.assert_not_awaited()
     assert model_data["hydrated"] is True
 
     helpers.metadata_manager.save_metadata.assert_awaited_once()
diff --git a/tests/services/test_route_support_services.py b/tests/services/test_route_support_services.py
index bde7abf2..544333ec 100644
--- a/tests/services/test_route_support_services.py
+++ b/tests/services/test_route_support_services.py
@@ -117,6 +117,7 @@ def test_metadata_sync_fetch_and_update_updates_cache(tmp_path: Path) -> None:
     )
 
     model_data = {"sha256": "abc", "file_path": str(tmp_path / "model.safetensors")}
+    asyncio.run(manager.hydrate_model_data(model_data))
     success, error = asyncio.run(
         service.fetch_and_update_model(
             sha256="abc",