并发模型: spawn派发协助分支 + 转交简化为单线 + 子分支未完成拦截(409)

backend/app/services/task_service.py

@@ -236,6 +236,9 @@ async def end_task(
     """
     task = await _get_task_or_404(db, task_id)
 
+    # 校验：必须等待所有协助分支完成
+    await _check_children_done(db, task_id)
+
     if task.status == TASK_STATUS_COMPLETED:
         raise HTTPException(status_code=409, detail="此分支已经结束")
     if task.status == TASK_STATUS_PENDING:
@@ -253,6 +256,62 @@ async def end_task(
     return _to_response(task)
 
 
+# ============================================================
+# 核心业务 0.5：派发协助分支（不改变父任务状态）
+# ============================================================
+
+async def spawn_subtask(
+    db: AsyncSession, task_id: uuid.UUID, data, operator_id: str | None = None
+) -> TaskResponse:
+    """在当前任务下创建并行子任务，父任务状态保持不变。"""
+    task = await _get_task_or_404(db, task_id)
+
+    if task.status == TASK_STATUS_COMPLETED:
+        raise HTTPException(status_code=409, detail="任务已完成，无法派发协助分支")
+    if task.status == TASK_STATUS_REJECTED:
+        raise HTTPException(status_code=409, detail="任务已驳回，无法派发协助分支")
+
+    child = Task(
+        product_id=task.product_id,
+        parent_task_id=task.id,
+        task_name=data.task_name,
+        assignee_id=data.assignee_id,
+        status=TASK_STATUS_PENDING,
+        notify_parent_on_complete=False,
+        is_rework=False,
+        remark=data.remark or None,
+    )
+    db.add(child)
+    await db.flush()
+
+    await _create_task_log(db, child.id, action_type="create", operator_id=operator_id,
+        remark=f"协助分支（由「{task.task_name}」派发，分配给 {data.assignee_id}）")
+    await db.commit()
+    await db.refresh(child)
+    return _to_response(child)
+
+
+async def _check_children_done(db: AsyncSession, task_id: uuid.UUID):
+    """检查当前任务的所有子任务是否都已完结。未完结则抛出 409。"""
+    result = await db.execute(
+        select(Task).where(Task.parent_task_id == task_id)
+    )
+    children = result.scalars().all()
+    incomplete = [c for c in children if c.status not in (
+        TASK_STATUS_COMPLETED, TASK_STATUS_REJECTED, ARCHIVED_STATUS
+    )]
+    if incomplete:
+        names = "、".join(c.task_name for c in incomplete)
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail=f"当前工序还有未完成的协助分支（{names}），必须等待分支结束才能转交或完工！",
+        )
+    return True
+
+
+ARCHIVED_STATUS = "ARCHIVED"
+
+
 # ============================================================
 # 核心业务 1：确认接收 (PENDING → WIP)
 # ============================================================
@@ -429,6 +488,9 @@ async def transfer_task(
     """
     task = await _get_task_or_404(db, task_id)
 
+    # 校验：必须等待所有协助分支完成
+    await _check_children_done(db, task_id)
+
     # 校验：不能重复完成
     if task.status == TASK_STATUS_COMPLETED:
         raise HTTPException(