Issue Description
模型一定概率返回llm_return_empty，有时候就直接卡顿在那了。
Steps to Reproduce
启动subagent，没有固定手顺。
Expected Behavior
正常返回子agent信息
Actual Behavior
返回"llm_return_empty"
Screenshots / Screen Recordings
Operating System
mac
Current Qoder Version (Menu → About Qoder → Copy)
Version: 1.2.3
VSCode Version: 1.106.3
Commit: 3926492a9efceff1539460705be11b058c0335f4
Date: 2026-05-23T03:21:43.204Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Darwin arm64 23.2.0