test: 补充编辑器预览产物复用逻辑单测

- _find_reusable_preview_task: 6 个用例（正常复用/无任务/未完成/plan已修改/非预览/异常）
- _get_task_output_url: 3 个用例（正常/空视频/异常）
- mark_confirmed: 5 个用例（is_preview/cover/title/dimensions）

tests/unit/test_unified_render_reuse.py

@@ -0,0 +1,261 @@
+"""统一渲染路径 — 编辑器预览产物复用逻辑单元测试。
+
+覆盖：
+- _find_reusable_preview_task: 查找可复用的预览任务
+- _get_task_output_url: 获取任务输出 URL
+- 编辑器 generate 接口复用预览产物路径
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+from dataclasses import dataclass, field
+from datetime import datetime, timedelta, timezone
+from typing import Any, Optional
+from unittest.mock import MagicMock, patch
+
+os.environ.setdefault("JWT_SECRET_KEY", "unit-test-secret-key-for-testing")
+os.environ.setdefault("DATABASE_URL", "sqlite:///test.db")
+
+import pytest
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "..", "apps", "api"))
+
+from packages.domain.generation_task import GenerationTask, GenerationTaskStatus
+
+# ── Stub Repository ──────────────────────────────────────────────────────────
+
+
+class StubGenTaskRepo:
+    def __init__(self):
+        self._store = {}
+
+    def create(self, task):
+        self._store[task.id] = task
+        return task
+
+    def get(self, task_id):
+        return self._store.get(task_id)
+
+    def update(self, task):
+        self._store[task.id] = task
+        return task
+
+    def list_by_source_edit_plan(self, plan_id):
+        return [t for t in self._store.values() if (t.source_edit_plan_id or "") == plan_id]
+
+
+def _make_task(**kwargs):
+    defaults = dict(
+        id="task-001",
+        project_id="proj-1",
+        asset_library_id="lib-1",
+        strategy_id="one_take",
+        voice_library_id="",
+        template_id="tmpl-1",
+        asset_ids=["a1"],
+        title_ids=[],
+        voice_ids=[],
+        status=GenerationTaskStatus.COMPLETED,
+        progress=100.0,
+        result_count=1,
+        error_message="",
+        created_by_user_id="user-1",
+        source_edit_plan_id="plan-1",
+        asset_select_mode="all",
+        is_preview=True,
+        source_task_id="",
+        output_width=1920,
+        output_height=1080,
+        cover_url="",
+        custom_title="",
+        video_title="",
+        resolution="",
+        bgm_config={},
+        completed_at=datetime.now(timezone.utc),
+    )
+    defaults.update(kwargs)
+    return GenerationTask(**defaults)
+
+
+def _make_plan(updated_at=None):
+    plan = MagicMock()
+    plan.id = "plan-1"
+    plan.updated_at = updated_at or datetime.now(timezone.utc)
+    plan.status = MagicMock()
+    plan.status.value = "editing"
+    plan.config = {"clips": [{"id": "c1"}, {"id": "c2"}]}
+    return plan
+
+
+# ── _find_reusable_preview_task ──────────────────────────────────────────────
+
+
+class TestFindReusablePreviewTask:
+    def test_returns_completed_preview_task(self):
+        from app.api.routes.templates_editor.generation import _find_reusable_preview_task
+
+        repo = StubGenTaskRepo()
+        now = datetime.now(timezone.utc)
+        task = _make_task(
+            source_edit_plan_id="plan-1",
+            is_preview=True,
+            status=GenerationTaskStatus.COMPLETED,
+            completed_at=now - timedelta(minutes=5),
+        )
+        repo.create(task)
+
+        plan = _make_plan(updated_at=now - timedelta(minutes=10))
+        result = _find_reusable_preview_task(repo, "plan-1", plan)
+
+        assert result is not None
+        assert result.id == "task-001"
+
+    def test_returns_none_when_no_tasks(self):
+        from app.api.routes.templates_editor.generation import _find_reusable_preview_task
+
+        repo = StubGenTaskRepo()
+        plan = _make_plan()
+        result = _find_reusable_preview_task(repo, "plan-1", plan)
+        assert result is None
+
+    def test_returns_none_when_preview_not_completed(self):
+        from app.api.routes.templates_editor.generation import _find_reusable_preview_task
+
+        repo = StubGenTaskRepo()
+        task = _make_task(
+            source_edit_plan_id="plan-1",
+            is_preview=True,
+            status=GenerationTaskStatus.RUNNING,
+            completed_at=None,
+        )
+        repo.create(task)
+
+        plan = _make_plan()
+        result = _find_reusable_preview_task(repo, "plan-1", plan)
+        assert result is None
+
+    def test_returns_none_when_plan_modified_after_preview(self):
+        from app.api.routes.templates_editor.generation import _find_reusable_preview_task
+
+        repo = StubGenTaskRepo()
+        now = datetime.now(timezone.utc)
+        task = _make_task(
+            source_edit_plan_id="plan-1",
+            is_preview=True,
+            status=GenerationTaskStatus.COMPLETED,
+            completed_at=now - timedelta(minutes=10),
+        )
+        repo.create(task)
+
+        # Plan was updated AFTER preview completed
+        plan = _make_plan(updated_at=now)
+        result = _find_reusable_preview_task(repo, "plan-1", plan)
+        assert result is None
+
+    def test_skips_non_preview_tasks(self):
+        from app.api.routes.templates_editor.generation import _find_reusable_preview_task
+
+        repo = StubGenTaskRepo()
+        task = _make_task(
+            source_edit_plan_id="plan-1",
+            is_preview=False,  # not a preview task
+            status=GenerationTaskStatus.COMPLETED,
+        )
+        repo.create(task)
+
+        plan = _make_plan()
+        result = _find_reusable_preview_task(repo, "plan-1", plan)
+        assert result is None
+
+    def test_handles_repo_exception(self):
+        from app.api.routes.templates_editor.generation import _find_reusable_preview_task
+
+        repo = MagicMock()
+        repo.list_by_source_edit_plan.side_effect = Exception("db error")
+        plan = _make_plan()
+        result = _find_reusable_preview_task(repo, "plan-1", plan)
+        assert result is None
+
+
+# ── _get_task_output_url ─────────────────────────────────────────────────────
+
+
+class TestGetTaskOutputUrl:
+    def test_returns_video_url(self):
+        from app.api.routes.templates_editor.generation import _get_task_output_url
+
+        task = _make_task()
+        repo = MagicMock()
+
+        mock_video = MagicMock()
+        mock_video.file_url = "https://oss.example.com/video.mp4"
+
+        with patch(
+            "app.api.routes.templates_editor.generation.get_generated_videos_for_task",
+            return_value=[mock_video],
+        ):
+            result = _get_task_output_url(task, repo)
+
+        assert result == "https://oss.example.com/video.mp4"
+
+    def test_returns_empty_when_no_videos(self):
+        from app.api.routes.templates_editor.generation import _get_task_output_url
+
+        task = _make_task()
+        repo = MagicMock()
+
+        with patch(
+            "app.api.routes.templates_editor.generation.get_generated_videos_for_task",
+            return_value=[],
+        ):
+            result = _get_task_output_url(task, repo)
+
+        assert result == ""
+
+    def test_returns_empty_on_exception(self):
+        from app.api.routes.templates_editor.generation import _get_task_output_url
+
+        task = _make_task()
+        repo = MagicMock()
+
+        with patch(
+            "app.api.routes.templates_editor.generation.get_generated_videos_for_task",
+            side_effect=Exception("db error"),
+        ):
+            result = _get_task_output_url(task, repo)
+
+        assert result == ""
+
+
+# ── mark_confirmed ───────────────────────────────────────────────────────────
+
+
+class TestMarkConfirmed:
+    def test_sets_is_preview_false(self):
+        task = _make_task(is_preview=True)
+        task.mark_confirmed()
+        assert task.is_preview is False
+
+    def test_sets_cover_url(self):
+        task = _make_task()
+        task.mark_confirmed(cover_url="https://example.com/cover.jpg")
+        assert task.cover_url == "https://example.com/cover.jpg"
+
+    def test_sets_custom_title(self):
+        task = _make_task()
+        task.mark_confirmed(custom_title="My Video")
+        assert task.custom_title == "My Video"
+
+    def test_sets_output_dimensions(self):
+        task = _make_task()
+        task.mark_confirmed(output_width=1080, output_height=1920)
+        assert task.output_width == 1080
+        assert task.output_height == 1920
+
+    def test_zero_dimensions_not_applied(self):
+        task = _make_task(output_width=1920, output_height=1080)
+        task.mark_confirmed(output_width=0, output_height=0)
+        assert task.output_width == 1920
+        assert task.output_height == 1080