fix(lora): skip a sidecar that is not UTF-8 instead of failing the load (#362)

Review follow-up on phase 4: read_lora_metadata caught JSONDecodeError but not
UnicodeDecodeError, so one non-UTF-8 sidecar failed the whole trigger-word
load (now logged with a traceback every retry) and the import review. It is
skipped like any unreadable sidecar. The relative preview_url DEBUG line uses
lazy formatting.

py/lora_manager_layout.py

@@ -577,7 +577,7 @@ def _preview_candidates(sidecar: Sidecar, metadata: Dict) -> Iterator[str]:
             # LoraManager writes absolute paths; it would resolve a relative
             # one against its working directory, not the sidecar folder.
             logger.debug(
-                f"Relative preview_url skipped in {sidecar.metadata_path.name}"
+                "Relative preview_url skipped in %s", sidecar.metadata_path.name
             )
     base = sidecar.metadata_path.name[: -len(METADATA_SUFFIX)]
     for suffix in PREVIEW_EXTENSIONS:

py/lora_utils.py

@@ -368,7 +368,7 @@ def read_lora_metadata(metadata_path: Path) -> Optional[Dict]:
     try:
         with open(metadata_path, "r", encoding="utf-8") as f:
             return json.load(f)
-    except (json.JSONDecodeError, OSError) as e:
+    except (ValueError, OSError) as e:  # JSONDecodeError, UnicodeDecodeError
         logger.debug(f"Failed to read {metadata_path}: {e}")
         return None
 

tests/test_api_images.py

@@ -1534,12 +1534,10 @@ class TestLoraManagerMediaServing(ImageRouteCoverageCase):
 
         self.assertEqual(await self._status(self._link_image(self._example())), 200)
         self.assertIsNotNone(lora_utils._layout_cache._entry)
-        stored = lora_utils._layout_cache._entry
         with patch.object(IntegrationConfig, "LORA_MANAGER_PATH", str(self.sidecars)):
             self.assertEqual(self.api._lora_image_dirs(), [])
         # The warm entry for the real install was never handed out for it.
         self.assertIsNone(lora_utils.cached_lora_manager_layout(str(self.sidecars))[0])
-        self.assertIsNotNone(stored)
 
     async def test_serve_image_builds_the_allow_list_in_the_executor(self):
         calls = self._spy_executor()

tests/test_lora_layout_cache.py

@@ -15,8 +15,8 @@ import tempfile
 import threading
 import time
 import unittest
-from pathlib import Path, PureWindowsPath
 from dataclasses import replace
+from pathlib import Path, PureWindowsPath
 from types import SimpleNamespace
 from unittest.mock import patch
 

tests/test_lora_utils.py

@@ -224,6 +224,14 @@ class TestReadLoraMetadata(unittest.TestCase):
         result = read_lora_metadata(Path("/nonexistent/file.metadata.json"))
         self.assertIsNone(result)
 
+    def test_returns_none_for_a_file_that_is_not_utf8(self):
+        # #362: one malformed sidecar is skipped; it must not fail the whole
+        # trigger-word load (now logged with a traceback) or the review.
+        with tempfile.TemporaryDirectory() as folder:
+            path = Path(folder) / "bad.metadata.json"
+            path.write_bytes(b'{"model_name": "\xff\xfe"}')
+            self.assertIsNone(read_lora_metadata(path))
+
 
 class TestGetLoraImageCacheDir(unittest.TestCase):
     """Test get_lora_image_cache_dir — returns and creates cache path."""