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/api/v1/endpoints/tasks.py

@@ -2,6 +2,7 @@
 from __future__ import annotations
 import uuid
 from fastapi import APIRouter, Depends, Query, Body
+from pydantic import BaseModel, Field
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.database import get_db
@@ -120,6 +121,30 @@ async def end_task_endpoint(
     return await task_service.end_task(db, uuid.UUID(task_id), operator_id)
 
 
+# ============================================================
+# 核心业务 0.5：并发派发协助分支 (WIP → 不改变状态，创建子任务)
+# ============================================================
+
+class SpawnRequest(BaseModel):
+    task_name: str = Field(..., max_length=200, description="工序名称")
+    assignee_id: str | None = Field(None, max_length=64, description="负责人ID")
+    remark: str | None = Field(None, max_length=2000, description="派发备注")
+
+
+@router.post("/{task_id}/spawn", response_model=TaskResponse, status_code=201)
+async def spawn_subtask_endpoint(
+    task_id: str,
+    data: SpawnRequest,
+    operator_id: str | None = Query(None),
+    db: AsyncSession = Depends(get_db),
+):
+    """
+    **派发协助分支：在当前任务下创建并行子任务，父任务状态保持不变。**
+    用于 WIP 期间工人需要其他人协助协同的场景。
+    """
+    return await task_service.spawn_subtask(db, uuid.UUID(task_id), data, operator_id)
+
+
 # ============================================================
 # 核心业务 1：确认接收 (PENDING → WIP)
 # ============================================================