**Please add a persistent default agent setting.

**Please add a persistent default agent setting.** Agent choice resets to base Copilot every new chat, so I must re-pick my custom agent each time. The app already remembers my default **model** — please do the same for **agents** (Settings dropdown or a `defaultAgent` key in `settings.json`).

---
| Field | Value |
| --- | --- |
| App version | 1.0.21 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Day 4 (Week 1) |

Start at the /chat flow and the Settings dropdown, then trace how the app persists the existing default model. Check whether settings.json is the relevant configuration location. Done means a selected custom agent remains the default when a new chat starts, with the existing model setting behavior preserved.

索引モデルが issue の本文から書いたものです。