test: 补充 _resolve_strategy_id_from_template 单元测试

- 新增 TestResolveStrategyIdFromTemplate (8个用例)
- 新增 TestPreviewRoutePassesStrategyId (2个用例)
- 修复已有 test_auto_infer_pip_resolution 适配新 import

tests/unit/test_generation_preview.py

@@ -1264,8 +1264,182 @@ class TestPreviewRouteAutoInfersVideoRatio:
             bgm_config={},
         )
 
-        with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockRepo:
-            MockRepo.return_value.get.return_value = mock_template
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = None  # 新模板系统无数据，fallback 旧系统
+            with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockRepo:
+                MockRepo.return_value.get.return_value = mock_template
+                with patch("app.api.routes.generation_preview.CreateGenerationTaskUseCase") as MockUC:
+                    MockUC.return_value.execute.return_value = task
+                    with patch(
+                        "app.api.routes.generation_preview.safe_enqueue_generation_task",
+                        return_value=True,
+                    ):
+                        resp = create_preview_generation_task(
+                            request,
+                            authenticated_user=_make_user(),
+                            generation_task_repository=repo,
+                            db=mock_db,
+                        )
+
+        # Verify the resolution passed to CreateGenerationTaskCommand
+        call_args = MockUC.return_value.execute.call_args
+        cmd = call_args[0][0]
+        assert cmd.resolution == "480x854", f"Expected 480x854, got {cmd.resolution}"
+
+# ═══════════════════════════════════════════════════════════════════════════════
+# _resolve_strategy_id_from_template 单元测试
+# ═══════════════════════════════════════════════════════════════════════════════
+
+
+class TestResolveStrategyIdFromTemplate:
+    """_resolve_strategy_id_from_template 单元测试：预览生成从模板读取 editing_mode。"""
+
+    def test_new_template_found_returns_editing_mode(self):
+        """新模板系统找到模板 → 返回 editing_mode。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_new_template = MagicMock()
+        mock_new_template.editing_mode = "pip"
+        mock_db = MagicMock()
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = mock_new_template
+            result = _resolve_strategy_id_from_template("tpl_001", mock_db, "user_1")
+
+        assert result == "pip"
+
+    def test_new_template_not_found_fallback_to_old(self):
+        """新模板系统未找到 → fallback 旧模板系统返回 mode。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_old_template = MagicMock()
+        mock_old_template.mode = "standard"
+        mock_db = MagicMock()
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = None
+            with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockOldRepo:
+                MockOldRepo.return_value.get.return_value = mock_old_template
+                result = _resolve_strategy_id_from_template("tpl_001", mock_db, "user_1")
+
+        assert result == "standard"
+
+    def test_both_not_found_returns_empty(self):
+        """新旧模板系统都未找到 → 返回空字符串。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_db = MagicMock()
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = None
+            with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockOldRepo:
+                MockOldRepo.return_value.get.return_value = None
+                result = _resolve_strategy_id_from_template("tpl_nonexistent", mock_db, "user_1")
+
+        assert result == ""
+
+    def test_empty_template_id_returns_empty(self):
+        """空 template_id → 直接返回空字符串。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_db = MagicMock()
+        result = _resolve_strategy_id_from_template("", mock_db, "user_1")
+        assert result == ""
+
+    def test_new_template_exception_fallback_to_old(self):
+        """新模板系统异常 → 降级到旧模板系统。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_old_template = MagicMock()
+        mock_old_template.mode = "voice_over"
+        mock_db = MagicMock()
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.side_effect = RuntimeError("db error")
+            with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockOldRepo:
+                MockOldRepo.return_value.get.return_value = mock_old_template
+                result = _resolve_strategy_id_from_template("tpl_001", mock_db, "user_1")
+
+        assert result == "voice_over"
+
+    def test_both_exception_returns_empty(self):
+        """新旧模板系统都异常 → 返回空字符串。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_db = MagicMock()
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.side_effect = RuntimeError("new db error")
+            with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockOldRepo:
+                MockOldRepo.side_effect = RuntimeError("old db error")
+                result = _resolve_strategy_id_from_template("tpl_001", mock_db, "user_1")
+
+        assert result == ""
+
+    def test_new_template_empty_editing_mode_fallback(self):
+        """新模板找到但 editing_mode 为空 → fallback 旧模板。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_new_template = MagicMock()
+        mock_new_template.editing_mode = ""
+        mock_old_template = MagicMock()
+        mock_old_template.mode = "one_take"
+        mock_db = MagicMock()
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = mock_new_template
+            with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockOldRepo:
+                MockOldRepo.return_value.get.return_value = mock_old_template
+                result = _resolve_strategy_id_from_template("tpl_001", mock_db, "user_1")
+
+        assert result == "one_take"
+
+    def test_voice_pip_mode(self):
+        """模板 editing_mode=voice_pip → 返回 'voice_pip'。"""
+        from app.api.routes.generation_preview import _resolve_strategy_id_from_template
+
+        mock_new_template = MagicMock()
+        mock_new_template.editing_mode = "voice_pip"
+        mock_db = MagicMock()
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = mock_new_template
+            result = _resolve_strategy_id_from_template("tpl_voice", mock_db, "user_1")
+
+        assert result == "voice_pip"
+
+
+class TestPreviewRoutePassesStrategyId:
+    """验证预览路由正确传递 strategy_id 到 CreateGenerationTaskCommand。"""
+
+    def test_strategy_id_from_new_template(self):
+        """预览路由从新模板读取 strategy_id=pip。"""
+        from app.api.routes.generation_preview import create_preview_generation_task
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        repo = MagicMock()
+        repo.count_pending_by_user.return_value = 0
+        repo.count_pending_total.return_value = 0
+        mock_db = MagicMock()
+
+        mock_new_template = MagicMock()
+        mock_new_template.editing_mode = "pip"
+
+        task = _make_task()
+
+        request = CreatePreviewGenerationTaskRequest(
+            template_id="tpl_pip",
+            asset_ids=["a1"],
+            title_ids=[],
+            voice_ids=[],
+            video_title="test",
+            duration=0.0,
+            video_ratio="",
+            bgm_config={},
+        )
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = mock_new_template
             with patch("app.api.routes.generation_preview.CreateGenerationTaskUseCase") as MockUC:
                 MockUC.return_value.execute.return_value = task
                 with patch(
@@ -1279,7 +1453,53 @@ class TestPreviewRouteAutoInfersVideoRatio:
                         db=mock_db,
                     )
 
-        # Verify the resolution passed to CreateGenerationTaskCommand
         call_args = MockUC.return_value.execute.call_args
         cmd = call_args[0][0]
-        assert cmd.resolution == "480x854", f"Expected 480x854, got {cmd.resolution}"
+        assert cmd.strategy_id == "pip", f"Expected strategy_id='pip', got '{cmd.strategy_id}'"
+
+    def test_strategy_id_fallback_to_old_template(self):
+        """新模板无数据时，从旧模板读取 strategy_id=standard。"""
+        from app.api.routes.generation_preview import create_preview_generation_task
+        from app.schemas.generation_task import CreatePreviewGenerationTaskRequest
+
+        repo = MagicMock()
+        repo.count_pending_by_user.return_value = 0
+        repo.count_pending_total.return_value = 0
+        mock_db = MagicMock()
+
+        mock_old_template = MagicMock()
+        mock_old_template.mode = "standard"
+
+        task = _make_task()
+
+        request = CreatePreviewGenerationTaskRequest(
+            template_id="tpl_standard",
+            asset_ids=["a1"],
+            title_ids=[],
+            voice_ids=[],
+            video_title="test",
+            duration=0.0,
+            video_ratio="",
+            bgm_config={},
+        )
+
+        with patch("app.api.routes.generation_preview.SQLAlchemyEditTemplateRepository") as MockNewRepo:
+            MockNewRepo.return_value.get.return_value = None
+            with patch("app.api.routes.generation_preview.SQLAlchemyTemplateRepository") as MockOldRepo:
+                MockOldRepo.return_value.get.return_value = mock_old_template
+                with patch("app.api.routes.generation_preview.CreateGenerationTaskUseCase") as MockUC:
+                    MockUC.return_value.execute.return_value = task
+                    with patch(
+                        "app.api.routes.generation_preview.safe_enqueue_generation_task",
+                        return_value=True,
+                    ):
+                        resp = create_preview_generation_task(
+                            request,
+                            authenticated_user=_make_user(),
+                            generation_task_repository=repo,
+                            db=mock_db,
+                        )
+
+        call_args = MockUC.return_value.execute.call_args
+        cmd = call_args[0][0]
+        assert cmd.strategy_id == "standard", f"Expected strategy_id='standard', got '{cmd.strategy_id}'"