fix(cache): harden metadata defaults

tests/services/test_model_cache_resilience.py

@@ -0,0 +1,47 @@
+import asyncio
+
+import pytest
+
+from py.services.model_cache import ModelCache
+from py.services.model_query import SearchStrategy
+
+
+@pytest.mark.asyncio
+async def test_model_cache_handles_missing_string_fields():
+    cache = ModelCache(
+        raw_data=[
+            {
+                "file_path": "/models/example.safetensors",
+                "file_name": None,
+                "model_name": None,
+                "folder": None,
+                "size": 0,
+                "modified": 0.0,
+            }
+        ],
+        folders=[],
+    )
+
+    await asyncio.sleep(0)  # allow background resort task to run
+    sorted_data = await cache.get_sorted_data("name", "asc")
+
+    assert sorted_data[0]["model_name"] == ""
+    assert sorted_data[0]["file_name"] == ""
+    assert cache.folders == [""]
+
+
+def test_search_strategy_handles_non_string_candidates():
+    strategy = SearchStrategy()
+    options = strategy.normalize_options(None)
+
+    data = [
+        {
+            "file_name": "example.safetensors",
+            "model_name": None,
+            "tags": ["test"],
+        }
+    ]
+
+    results = strategy.apply(data, "example", options)
+
+    assert data[0] in results