diff --git a/pipeline_service/agent_loop.py b/pipeline_service/agent_loop.py
index 48d2e87..05d896f 100644
--- a/pipeline_service/agent_loop.py
+++ b/pipeline_service/agent_loop.py
@@ -624,6 +624,16 @@ async def _create_next_task(sor, project_id, task, next_role, pm_comment=''):
     return new_task_id, new_title
 
 
+def _task_iteration_name(task):
+    """提取任务的迭代名（params.iteration_id，存的是迭代名称非 id）。"""
+    params_str = getattr(task, 'params', '{}') or '{}'
+    try:
+        params = json.loads(params_str) if isinstance(params_str, str) else params_str
+        return (params.get('iteration_id') or '').strip()
+    except (json.JSONDecodeError, TypeError):
+        return ''
+
+
 # ── Agent 工具执行 ──
 
 def _parse_agent_action(raw):
@@ -1166,6 +1176,17 @@ async def pm_review_run(project_id, agent_id=None, model_name=None):
             await approve_task(task_id, project_id, who="agent.pm", agent_id=agent_id, comment=comment)
             next_role = await _get_next_role(task_role, project_id)
             if next_role:
+                # 迭代边界：任务若归属老迭代（非当前迭代=该项目最新创建的迭代），
+                # 链到此终止，不再自动触发下一角色任务——「新迭代创建后老迭代不再产生新任务」。
+                task_iter = _task_iteration_name(task)
+                if task_iter:
+                    cur = await sor.sqlExe(
+                        "SELECT iteration_name FROM sd_iterations WHERE project_id=${pid}$ ORDER BY created_at DESC LIMIT 1",
+                        {"pid": project_id})
+                    cur_name = getattr(cur[0], 'iteration_name', '') if cur else ''
+                    if cur_name and task_iter != cur_name:
+                        logger.info(f"迭代边界：任务 {task_id} 归属老迭代「{task_iter}」(当前「{cur_name}」)，链终止")
+                        return {"status": "completed", "task_id": task_id, "comment": comment or "迭代已结束，链终止"}
                 next_tid, next_title = await _create_next_task(sor, project_id, task, next_role, comment)
                 return {"status": "approved", "task_id": task_id, "next_task_id": next_tid, "next_role": next_role, "comment": comment}
             else: