App appears unresponsive (no agent reply) while window stays interactive — not frozen

**Mood:** 😞
**Category:** Bug

The Copilot app stopped responding to chat messages for an extended period (several minutes) while the window stayed fully interactive — it was **not** frozen. I could type in the composer, switch between sessions, and click UI controls, but the agent never produced a response to messages I'd sent. Follow-up messages (e.g. "are you there?") also got no reply until a restart of app, with no error, no spinner, and no "working" indicator to signal whether the turn was still in flight or had silently stalled. After restart, those messages disappeared.

**Expected:** when a turn is in flight, the app should show a clear working/streaming indicator; if the turn stalls or errors, it should surface that instead of silently appearing hung while the rest of the window stays responsive.

---
| Field | Value |
| --- | --- |
| App version | 1.0.64-1 |
| OS | Windows 10.0.26200 |
| Theme | Dark |
| Path | /chat |

Beginne am Einstiegspunkt /chat und reproduziere das Problem unter Windows 10 mit der App-Version 1.0.64-1, während du einen Chat-Turn und eine Folgeanfrage sendest. Verfolge den Lebenszyklus des Turns und seine sichtbare Statusbehandlung; als abgeschlossen gilt die Aufgabe, wenn ein laufender Turn einen eindeutigen Arbeits-/Streaming-Status hat und Stillstände oder Fehler angezeigt werden, statt dass er scheinbar lautlos hängen bleibt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.