fix: 生成任务入队失败时标记为failed，避免pending僵尸任务

根因：任务创建(DB commit)和入队(Celery send_task)是两个独立操作，
send_task失败时任务卡在pending状态永远不会执行。

修复：
- 新增_safe_enqueue_generation_task安全入队函数
- send_task失败时自动标记任务为failed并记录错误
- 覆盖4处入口：批量创建、generation重试、task_center两级重试

apps/api/app/api/routes/generation_tasks.py

@@ -37,6 +37,43 @@ logger = logging.getLogger(__name__)
 router = APIRouter()
 
 
+def _safe_enqueue_generation_task(
+    task: Any,
+    generation_task_repository: Any,
+) -> bool:
+    """安全入队：send_task 失败时自动把任务标记为 failed，避免留下 pending 僵尸任务。
+
+    Returns:
+        True 表示入队成功，False 表示入队失败（已标记为 failed）
+    """
+    try:
+        celery_app.send_task("worker.generate_video", args=[task.id])
+        logger.info(
+            "[生成任务] 入队成功: task_id=%s, status=%s",
+            task.id,
+            task.status,
+        )
+        return True
+    except Exception as e:
+        logger.error(
+            "[生成任务] 入队失败，标记为失败: task_id=%s error=%s",
+            task.id,
+            e,
+            exc_info=True,
+        )
+        try:
+            task.mark_failed(f"任务入队失败: {e}")
+            generation_task_repository.update(task)
+        except Exception as update_err:
+            logger.error(
+                "[生成任务] 入队失败后更新状态也失败: task_id=%s error=%s",
+                task.id,
+                update_err,
+                exc_info=True,
+            )
+        return False
+
+
 def _check_project_access(project_id: str, user_id: str, project_repository) -> None:
     """检查用户是否有项目访问权限"""
     project = project_repository.find_by_id(project_id)
@@ -228,6 +265,7 @@ def create_generation_task(
     use_case = CreateGenerationTaskUseCase(generation_task_repository)
     count = request.count
     created_tasks = []
+    failed_tasks = []
     # 同批次任务共享 batch_id，用于视频查重时批次内比对
     batch_id = uuid.uuid4().hex if count > 1 else ""
 
@@ -249,19 +287,15 @@ def create_generation_task(
                     batch_id=batch_id,
                 )
             )
-            celery_app.send_task("worker.generate_video", args=[task.id])
-            created_tasks.append(task)
-            logger.info(
-                "[生成任务] 入队成功: task_id=%s, status=%s, batch_id=%s",
-                task.id,
-                task.status,
-                batch_id,
-            )
+            if _safe_enqueue_generation_task(task, generation_task_repository):
+                created_tasks.append(task)
+            else:
+                failed_tasks.append(task)
     except Exception as e:
         logger.error("[生成任务] 创建失败: %s", e, exc_info=True)
         raise HTTPException(status_code=500, detail="创建生成任务失败，请稍后重试或查看任务日志")
 
-    items = [_to_generation_task_response(t) for t in created_tasks]
+    items = [_to_generation_task_response(t) for t in created_tasks + failed_tasks]
     return BatchGenerationTaskResponse(items=items, total=len(items))
 
 
@@ -347,5 +381,6 @@ def retry_generation_task(
             asset_select_mode=getattr(task, "asset_select_mode", ""),
         )
     )
-    celery_app.send_task("worker.generate_video", args=[retried.id])
+    if not _safe_enqueue_generation_task(retried, generation_task_repository):
+        logger.warning("[生成任务] 重试入队失败: task_id=%s", retried.id)
     return _to_generation_task_response(retried)

apps/api/app/api/routes/task_center.py

@@ -25,6 +25,35 @@ from packages.application import (
 router = APIRouter()
 
 
+def _safe_enqueue_generation_task(
+    task: Any,
+    generation_task_repository: Any,
+) -> bool:
+    """安全入队：send_task 失败时自动把任务标记为 failed，避免留下 pending 僵尸任务。"""
+    try:
+        celery_app.send_task("worker.generate_video", args=[task.id])
+        logger.info("[任务中心] 生成任务入队成功: task_id=%s", task.id)
+        return True
+    except Exception as e:
+        logger.error(
+            "[任务中心] 生成任务入队失败，标记为失败: task_id=%s error=%s",
+            task.id,
+            e,
+            exc_info=True,
+        )
+        try:
+            task.mark_failed(f"任务入队失败: {e}")
+            generation_task_repository.update(task)
+        except Exception as update_err:
+            logger.error(
+                "[任务中心] 入队失败后更新状态也失败: task_id=%s error=%s",
+                task.id,
+                update_err,
+                exc_info=True,
+            )
+        return False
+
+
 def _humanize_task_error(error_message: str) -> str:
     raw = (error_message or "").strip()
     if not raw:
@@ -153,7 +182,8 @@ def retry_task_by_id(
             created_by_user_id=authenticated_user.user.id,
         )
     )
-    celery_app.send_task("worker.generate_video", args=[retried.id])
+    if not _safe_enqueue_generation_task(retried, generation_task_repository):
+        logger.warning("[任务中心] 用户级重试入队失败: task_id=%s", retried.id)
     return UserTaskResponse(
         id=f"generation:{retried.id}",
         task_type="generation",
@@ -235,7 +265,8 @@ def retry_project_task(
                 created_by_user_id=authenticated_user.user.id,
             )
         )
-        celery_app.send_task("worker.generate_video", args=[retried.id])
+        if not _safe_enqueue_generation_task(retried, generation_task_repository):
+            logger.warning("[任务中心] 项目级重试用队失败: task_id=%s", retried.id)
         return _generation_task_to_project_response(retried)
     if task_type == "ingest":
         job = ingest_job_repository.get(source_id)