refactor: add durable transfer planning checkpoints

tests/test_storage_chain_strict.py

@@ -0,0 +1,43 @@
+"""StorageChain 严格查询的三态传播合同。"""
+
+from pathlib import Path
+from unittest.mock import Mock
+
+import pytest
+
+from app.chain.storage import StorageChain
+from app.modules.filemanager.module import FileManagerModule
+from app.schemas.exception import StorageQueryError
+
+
+def test_storage_chain_strict_query_distinguishes_absent_and_failure() -> None:
+    """严格查询用 None 表示确认不存在，并原样传播 provider 查询失败。"""
+    chain = object.__new__(StorageChain)
+    chain._module_dispatcher = Mock()
+    chain._module_dispatcher.dispatch_strict.return_value = None
+
+    assert chain.get_file_item_strict("plugin", Path("/missing.mkv")) is None
+
+    chain._module_dispatcher.dispatch_strict.side_effect = StorageQueryError(
+        "provider lookup failed"
+    )
+    with pytest.raises(StorageQueryError, match="provider lookup failed"):
+        chain.get_file_item_strict("plugin", Path("/unknown.mkv"))
+
+
+def test_filemanager_storage_query_uses_strict_storage_adapter(monkeypatch) -> None:
+    """宿主存储 provider 必须调用 get_item_strict，不能回退会吞错的 get_item。"""
+    module = object.__new__(FileManagerModule)
+    module._support_storages = ["local"]
+    storage = Mock()
+    storage.get_item_strict.side_effect = StorageQueryError("local stat failed")
+    monkeypatch.setattr(
+        module,
+        "_FileManagerModule__get_storage_oper",
+        lambda _storage: storage,
+    )
+
+    with pytest.raises(StorageQueryError, match="local stat failed"):
+        module.get_file_item("local", Path("/library/old.mkv"))
+
+    storage.get_item.assert_not_called()