The app freezes regularly when I want to attach a file to a session.

The app freezes regularly when I want to attach a file to a session. It freezes at the click at the "+" icon

---
| Field | Value |
| --- | --- |
| App version | 1.0.25 |
| OS | macOS 15.7.3 |
| Theme | Mondrian |
| Path | /chat |
| Tenure | Week 3 |

Reproduce the freeze in app version 1.0.25 on macOS 15.7.3 by opening the /chat path and clicking the "+" icon to attach a file. Trace the file-attachment flow from that entry point; done means the app no longer freezes when the attachment control is clicked.

索引モデルが issue の本文から書いたものです。