Response interrupted and I cannot work anymore...

### Describe the bug

On Copilot CLI, after a bit, I encounter these errors:

● Response was interrupted due to a server error. Retrying...

● Response was interrupted due to a server error. Retrying...

● Response was interrupted due to a server error. Retrying...

● Response was interrupted due to a server error. Retrying...

● Response was interrupted due to a server error. Retrying...

✗ Execution failed: Error: Failed to get response from the AI model; retried 5 times (total retry wait time: 6.33 seconds) Last error: Unknown error

When this happens, there’s no way to continue working, the flow is blocked and I have to start a new chat.

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_

まず、Copilot CLI で server-error の再試行シーケンスが繰り返される状況を再現し、影響を受けたバージョンを含むエラーコンテキスト全体を取得します。報告されたエラーメッセージを起点に、レスポンスと再試行のフローを追跡します。レスポンスの中断によって現在のチャットが恒久的にブロックされなくなり、復旧パスに対する回帰テストが用意されていれば完了です。

索引モデルが issue の本文から書いたものです。