Include oversized Synology photos through existing read-only XL previews

tests/test_photo_captions.py

@@ -125,3 +125,37 @@ def test_curated_catalog_includes_photos_beyond_old_ten_thousand_limit(
         ),
     )
     assert len(service.photo_sources.catalog("all")) == 10001
+
+
+def test_oversized_synology_photo_uses_read_only_cached_preview(service, settings):
+    root = settings.data_dir.parent / "synology"
+    settings.photo_root = root
+    settings.max_bytes = 1000
+    original = root / "20261005 出游@金山" / "large.jpg"
+    original.parent.mkdir(parents=True)
+    original.write_bytes(b"x" * 1001)
+    preview = original.parent / "@eaDir" / original.name / "SYNOPHOTO_THUMB_XL.jpg"
+    preview.parent.mkdir(parents=True)
+    Image.new("RGB", (20, 20), "blue").save(preview)
+    source = PhotoSourceInput(
+        name="Synology",
+        kind="local",
+        location=".",
+        organized_only=True,
+        folder_caption=True,
+        synology_previews=True,
+    )
+    service.photo_sources.save("synology", source)
+    items = service.photo_sources.catalog("synology")
+    assert len(items) == 1 and items[0]["provider_preview"]
+    data, name, caption = service.photo_sources.read("synology")
+    assert (
+        data == preview.read_bytes()
+        and name == "large.jpg"
+        and caption["place"] == "金山"
+    )
+    assert original.read_bytes() == b"x" * 1001
+    service.photo_sources.save(
+        "synology", source.model_copy(update={"synology_previews": False})
+    )
+    assert service.photo_sources.catalog("synology") == []