[Requests and ideas] Add a Tab sytem like a browser.

**Mood:** 😊
**Category:** Requests and ideas

Add a Tab sytem like a browser. I want to have one instance of Github Copilot open, but I want to be able to switch between sessions by going between Tabs. If I close it with three tabs open, then open it next time with those same three tabs. Let me decide when to close a tab.

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| Field | Value |
| --- | --- |
| App version | 1.0.6 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Week 6 |

Start with the app's /chat experience and map how multiple sessions should appear as tabs. Define the expected behavior for switching sessions, explicitly closing tabs, and restoring open tabs after restarting the app. Done means these three workflows are implemented consistently on Windows.

索引モデルが issue の本文から書いたものです。