[Bugs]: Custom agents not showing

**Mood:** 😔
**Category:** General

I have custom agents defined in `.github/agents` and they are not available when i run the `/agent` command.

---
| Field | Value |
| --- | --- |
| App version | 1.0.1 |
| OS | Windows 10.0.26200 |
| Theme | Tokyo Night |
| Path | /chat |
| Tenure | Week 2 |

Start by reproducing the issue in the GitHub Copilot app on the /chat path with a custom agent defined in .github/agents, then trace how the /agent command discovers available agents. Done means custom agents from that location appear and can be selected with /agent.

索引モデルが issue の本文から書いたものです。