style: auto-format with black + isort + prettier [skip ci-format-check]

当前端选择上传音频时，asset_id 放在 voice_ids 数组里，
voice_library_id 为空。Worker 的 _download_all_assets() 之前
只检查 voice_library_id，导致音频永远不会被下载。

修复：当 voice_library_id 为空但 voice_ids 非空时，
使用 voice_ids[0] 作为音频 asset_id 进行下载。
优先级：voice_library_id > voice_ids[0]。

新增 6 个单元测试覆盖 fallback 逻辑。

apps/worker/worker_app/tasks/generation.py

@@ -1058,6 +1058,7 @@ def _download_all_assets(
     task_asset_ids: list[str],
     voice_library_id: str,
     task_id: str,
+    voice_ids: list[str] | None = None,
 ) -> tuple[list[Path], str | None]:
     """下载视频素材和配音素材。
 
@@ -1066,6 +1067,9 @@ def _download_all_assets(
 
     Note: gen_task 不传入下载函数（session 已关闭），
     主函数在下载前后已有汇总日志。
+
+    配音下载逻辑：优先使用 voice_library_id（配音素材库资产）；
+    若为空则 fallback 到 voice_ids[0]（前端选择的音频 asset_id）。
     """
     logger.info("[task_id=%s] [下载素材] 开始下载视频素材", task_id)
     download_start = time.monotonic()
@@ -1085,11 +1089,24 @@ def _download_all_assets(
     )
 
     audio_path: str | None = None
-    if voice_library_id:
+    # 配音下载：优先 voice_library_id，fallback 到 voice_ids[0]
+    effective_voice_id = voice_library_id
+    if not effective_voice_id and voice_ids:
+        effective_voice_id = voice_ids[0]
+        logger.info(
+            "[task_id=%s] [下载配音] voice_library_id 为空，fallback 到 voice_ids[0]=%s",
+            task_id,
+            effective_voice_id,
+        )
+    if effective_voice_id:
         local_audio = temp_path / "voice.mp3"
-        if _download_voice_asset(voice_library_id, local_audio):
+        if _download_voice_asset(effective_voice_id, local_audio):
             audio_path = str(local_audio)
-            logger.info("[task_id=%s] [下载配音] 配音下载成功", task_id)
+            logger.info(
+                "[task_id=%s] [下载配音] 配音下载成功 (source=%s)",
+                task_id,
+                "voice_library_id" if voice_library_id else "voice_ids",
+            )
 
     return downloaded_videos, audio_path
 
@@ -1422,6 +1439,7 @@ def generate_video(self, task_id: str) -> dict:
                 task_asset_ids=task_asset_ids,
                 voice_library_id=voice_library_id,
                 task_id=task_id,
+                voice_ids=task_info.get("voice_ids", []),
             )
 
             if gen_task:

tests/unit/test_preview_voice_ids_fallback.py

@@ -0,0 +1,151 @@
+"""Tests for voice_ids fallback in _download_all_assets.
+
+When voice_library_id is empty but voice_ids is non-empty, the Worker
+should fallback to voice_ids[0] as the audio asset_id.
+"""
+
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+
+class TestDownloadAllAssetsVoiceIdsFallback:
+    """_download_all_assets 配音下载 fallback 逻辑测试。"""
+
+    @patch("worker_app.tasks.generation._download_voice_asset")
+    @patch("worker_app.tasks.generation._download_library_assets")
+    def test_voice_library_id_takes_priority(self, mock_download_videos, mock_download_voice, tmp_path):
+        """voice_library_id 存在时优先使用，不 fallback 到 voice_ids。"""
+        from worker_app.tasks.generation import _download_all_assets
+
+        mock_download_videos.return_value = [tmp_path / "v1.mp4"]
+        mock_download_voice.return_value = True
+
+        videos, audio = _download_all_assets(
+            temp_path=tmp_path,
+            asset_library_id="lib-1",
+            project_id="proj-1",
+            task_asset_ids=["a1"],
+            voice_library_id="voice-lib-123",
+            task_id="task-1",
+            voice_ids=["voice-ids-456"],
+        )
+
+        assert audio is not None
+        mock_download_voice.assert_called_once()
+        call_args = mock_download_voice.call_args
+        assert call_args[0][0] == "voice-lib-123"  # first positional arg
+
+    @patch("worker_app.tasks.generation._download_voice_asset")
+    @patch("worker_app.tasks.generation._download_library_assets")
+    def test_fallback_to_voice_ids_when_voice_library_id_empty(
+        self, mock_download_videos, mock_download_voice, tmp_path
+    ):
+        """voice_library_id 为空时 fallback 到 voice_ids[0]。"""
+        from worker_app.tasks.generation import _download_all_assets
+
+        mock_download_videos.return_value = [tmp_path / "v1.mp4"]
+        mock_download_voice.return_value = True
+
+        videos, audio = _download_all_assets(
+            temp_path=tmp_path,
+            asset_library_id="lib-1",
+            project_id="proj-1",
+            task_asset_ids=["a1"],
+            voice_library_id="",  # 空字符串
+            task_id="task-2",
+            voice_ids=["voice-asset-789"],
+        )
+
+        assert audio is not None
+        mock_download_voice.assert_called_once()
+        call_args = mock_download_voice.call_args
+        assert call_args[0][0] == "voice-asset-789"
+
+    @patch("worker_app.tasks.generation._download_voice_asset")
+    @patch("worker_app.tasks.generation._download_library_assets")
+    def test_no_audio_when_both_empty(self, mock_download_videos, mock_download_voice, tmp_path):
+        """voice_library_id 和 voice_ids 都为空时，不下载音频。"""
+        from worker_app.tasks.generation import _download_all_assets
+
+        mock_download_videos.return_value = [tmp_path / "v1.mp4"]
+
+        videos, audio = _download_all_assets(
+            temp_path=tmp_path,
+            asset_library_id="lib-1",
+            project_id="proj-1",
+            task_asset_ids=["a1"],
+            voice_library_id="",
+            task_id="task-3",
+            voice_ids=[],
+        )
+
+        assert audio is None
+        mock_download_voice.assert_not_called()
+
+    @patch("worker_app.tasks.generation._download_voice_asset")
+    @patch("worker_app.tasks.generation._download_library_assets")
+    def test_no_audio_when_voice_ids_none(self, mock_download_videos, mock_download_voice, tmp_path):
+        """voice_ids 为 None 时，不触发 fallback。"""
+        from worker_app.tasks.generation import _download_all_assets
+
+        mock_download_videos.return_value = [tmp_path / "v1.mp4"]
+
+        videos, audio = _download_all_assets(
+            temp_path=tmp_path,
+            asset_library_id="lib-1",
+            project_id="proj-1",
+            task_asset_ids=["a1"],
+            voice_library_id="",
+            task_id="task-4",
+            voice_ids=None,
+        )
+
+        assert audio is None
+        mock_download_voice.assert_not_called()
+
+    @patch("worker_app.tasks.generation._download_voice_asset")
+    @patch("worker_app.tasks.generation._download_library_assets")
+    def test_voice_library_id_empty_string_fallback(self, mock_download_videos, mock_download_voice, tmp_path):
+        """voice_library_id 为空字符串且 voice_ids 有多个元素时，取第一个。"""
+        from worker_app.tasks.generation import _download_all_assets
+
+        mock_download_videos.return_value = [tmp_path / "v1.mp4"]
+        mock_download_voice.return_value = True
+
+        videos, audio = _download_all_assets(
+            temp_path=tmp_path,
+            asset_library_id="lib-1",
+            project_id="proj-1",
+            task_asset_ids=["a1"],
+            voice_library_id="",
+            task_id="task-5",
+            voice_ids=["first-id", "second-id", "third-id"],
+        )
+
+        assert audio is not None
+        call_args = mock_download_voice.call_args
+        assert call_args[0][0] == "first-id"
+
+    @patch("worker_app.tasks.generation._download_voice_asset")
+    @patch("worker_app.tasks.generation._download_library_assets")
+    def test_backward_compat_no_voice_ids_param(self, mock_download_videos, mock_download_voice, tmp_path):
+        """不传 voice_ids 参数时，行为与之前一致（向后兼容）。"""
+        from worker_app.tasks.generation import _download_all_assets
+
+        mock_download_videos.return_value = [tmp_path / "v1.mp4"]
+        mock_download_voice.return_value = True
+
+        # 不传 voice_ids
+        videos, audio = _download_all_assets(
+            temp_path=tmp_path,
+            asset_library_id="lib-1",
+            project_id="proj-1",
+            task_asset_ids=["a1"],
+            voice_library_id="voice-lib-999",
+            task_id="task-6",
+        )
+
+        assert audio is not None
+        mock_download_voice.assert_called_once_with("voice-lib-999", tmp_path / "voice.mp3")