fix(worker): P0 修复@celery_app.task装饰器错位导致所有生成任务崩溃

装饰器被误放在辅助函数 _sync_task_config_to_plan 上，导致
worker.generate_video 实际执行的是该辅助函数，Celery只传task_id
即抛 TypeError: missing db，staging 所有生成任务崩溃。

修复：
1. 将 @celery_app.task 移到真正的 generate_video 函数上方
2. _sync_task_config_to_plan 恢复为普通函数
3. 同步补回配音临时文件清理（squash合并时丢失）
4. 新增3个防回归单测，断言任务名/签名/辅助函数无装饰器

运行时验证：
- generate_video.name == worker.generate_video
- signature: (task_id: str) -> dict

apps/worker/worker_app/tasks/generation.py

@@ -978,7 +978,7 @@ def _render_video(
 
     Args:
     Returns:
-        (output_path, render_duration, cover_candidates)
+        (output_path, render_duration, cover_candidates, voiceover_path)
     """
     if not downloaded_videos:
         raise RuntimeError(f"素材下载结果为空: task_id={task_id}")
@@ -1206,13 +1206,6 @@ def _upload_and_record(
 # ── Celery Task ──────────────────────────────────────────────────────────────
 
 
-@celery_app.task(
-    bind=True,
-    name="worker.generate_video",
-    max_retries=2,
-    soft_time_limit=600,  # 10 分钟软超时
-    time_limit=660,  # 11 分钟硬超时
-)
 def _sync_task_config_to_plan(source_edit_plan_id: str, task_info: dict, db) -> str | None:
     """将 GenerationTask 的配置同步到 EditPlan.config，返回配音本地路径（如果有）。
 
@@ -1295,7 +1288,7 @@ def _render_from_edit_plan(
     """从 EditPlan 数据库记录直接渲染（不再内存重建clips）。
 
     Returns:
-        (output_path, render_duration, cover_candidates)
+        (output_path, render_duration, cover_candidates, voiceover_path)
     """
     from video_processing.render_adapter import RenderAdapter
     from worker_app.db import SessionLocal
@@ -1335,13 +1328,18 @@ def _render_from_edit_plan(
         output_path = result.output_path
         cover_candidates = getattr(result, "cover_candidates", None)
 
-        return output_path, result.duration, cover_candidates
+        return output_path, result.duration, cover_candidates, voiceover_path
     finally:
         db.close()
-        # 清理临时配音文件
-        # voiceover_path 在外部作用域，这里不直接引用
 
 
+@celery_app.task(
+    bind=True,
+    name="worker.generate_video",
+    max_retries=2,
+    soft_time_limit=600,  # 10 分钟软超时
+    time_limit=660,  # 11 分钟硬超时
+)
 def generate_video(self, task_id: str) -> dict:
     """生成视频任务 — 使用 UnifiedRenderService 统一渲染。
 
@@ -1439,7 +1437,7 @@ def generate_video(self, task_id: str) -> dict:
                 gen_task.append_log("渲染模式", "从草稿数据渲染（与预览一致）")
                 _flush_logs(task_id, gen_task)
 
-            output_path, render_duration, cover_candidates = _render_from_edit_plan(
+            output_path, render_duration, cover_candidates, voiceover_tmp_path = _render_from_edit_plan(
                 task_id=task_id,
                 source_edit_plan_id=source_edit_plan_id,
                 task_info=task_info,
@@ -1587,6 +1585,13 @@ def generate_video(self, task_id: str) -> dict:
                 file_size,
             )
 
+            # 清理临时配音文件
+            if voiceover_tmp_path:
+                try:
+                    Path(voiceover_tmp_path).unlink(missing_ok=True)
+                except OSError:
+                    logger.warning("[task_id=%s] 清理临时配音文件失败: %s", task_id, voiceover_tmp_path)
+
             return {
                 "status": "completed",
                 "task_id": task_id,

tests/unit/test_worker_generate_video_task_binding.py

@@ -0,0 +1,40 @@
+"""Regression test: ensure worker.generate_video Celery task is bound to the
+real generate_video function, not a helper introduced above it.
+
+Context (P0 incident 2026-08-23): a refactor inserted helper function
+_sync_task_config_to_plan directly under the @celery_app.task decorator,
+so Celery registered the helper as "worker.generate_video". Calling the
+task with a single task_id raised TypeError and every generation job
+failed immediately. This test pins the decorator target.
+"""
+
+from __future__ import annotations
+
+import inspect
+
+
+def test_generate_video_task_registered_under_expected_name():
+    from worker_app.tasks.generation import generate_video
+
+    # Celery task object exposes its registered name
+    assert generate_video.name == "worker.generate_video"
+
+
+def test_generate_video_task_signature_has_task_id():
+    from worker_app.tasks.generation import generate_video
+
+    # The underlying callable must accept (self, task_id) for bind=True tasks
+    sig = inspect.signature(generate_video.run)
+    assert "task_id" in sig.parameters
+    # The first positional arg after self must be task_id
+    params = list(sig.parameters)
+    assert params[0] == "task_id"
+
+
+def test_sync_task_config_to_plan_is_plain_function():
+    """Helper must NOT be registered as a Celery task."""
+    from worker_app.tasks.generation import _sync_task_config_to_plan
+
+    assert not hasattr(_sync_task_config_to_plan, "run"), (
+        "_sync_task_config_to_plan must be a plain function, not a Celery task"
+    )