Cannot reliably change the Agent

Cannot reliably change the Agent

When trying to change the Agent, it often just no-ops without any feedback. I've also seen it show as though the agent has been changed, but then after the next prompt it reverts to the Default agent.

I have not yet found a reliable pattern or repro.

---
| Field | Value |
| --- | --- |
| App version | 1.0.25 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 3 |

Start in the /chat experience and try changing the Agent on app version 1.0.25 under Windows 10. Investigate the reported no-op and reversion to the Default agent; done means an agent change gives feedback and remains selected after the next prompt.

索引モデルが issue の本文から書いたものです。