Why can't we rename the session from the agent more than once?

Why can't we rename the session from the agent more than once? I want to have the agent update the session display name so I can keep track of status, what I'm working on in that session, etc.

---
| Field | Value |
| --- | --- |
| App version | 1.0.19 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 3 |

Start by reproducing the rename behavior in the /chat experience on the reported app version and observe what happens when the agent updates the session display name a second time. Trace the session naming entry point and existing rename handling, then verify that repeated agent-driven updates change the displayed name and do not break the session.

索引モデルが issue の本文から書いたものです。