After an approved plan is implemented by the agent, if I want to add somethin...

After an approved plan is implemented by the agent, if I want to add something more to the plan in the same session, the plan description doesn't get updated, only the to-do list gets updated unless I manually tell it to do so. Please fix this to update the plan description before I can check and approve it again.

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| Field | Value |
| --- | --- |
| App version | 1.1.10 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 11 |

Start in the /chat flow and reproduce the case in which an approved plan receives additional work in the same session. Check how the plan description and to-do list are updated before approval. Done means the description reflects the added work before the user can review and approve the plan again; verify the existing to-do update behavior remains intact.

索引モデルが issue の本文から書いたものです。