[General] Session artifact & todo cleanup?

**Mood:** 😊
**Category:** General

Session artifact & todo cleanup? During a long refactor in one session, plan/scratch files accrued and I had to manually request cleanup. Completed todos also kept piling up (stuck at 27/27 done but still accumulating). Unclear which layer should handle this.

---
| Field | Value |
| --- | --- |
| App version | 0.2.34 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 2 |

没有指定文件、测试或入口点。首先跟踪 /chat 会话的生命周期，并确定 plan/scratch 工件和已完成的 todo 存储或显示在哪里。完成的标准是 issue 定义并验证自动清理，既不删除活动中的工作，也不允许已完成的 todo 不断累积。

由索引模型根据 Issue 内容生成。