[Requests and ideas] Preserve user prompts when session creation fails

**Mood:** 😔
**Category:** Requests and ideas

I spent several minutes crafting a prompt in the GitHub Copilot app and hit Enter, only to receive a "Session creation failed" error. Looking at GitHub Status, I can see there was an active Copilot availability issue, so the failure itself is understandable. See https://www.githubstatus.com/incidents/rfmjwng33vjf.

The frustrating part is that there appears to be no way to recover or even view the prompt that was just submitted. As a result, the entire prompt has to be recreated from scratch.

Feature suggestion: When session creation fails, preserve the user's prompt and allow it to be retried, copied, or recovered. Even a temporary draft recovery mechanism would prevent users from losing potentially lengthy prompts during transient service outages.

---
| Field | Value |
| --- | --- |
| App version | 0.2.29 |
| OS | macOS 26.5.0 |
| Theme | GitHub |
| Path | /chat |
| Tenure | Day 7 (Week 1) |

从 /chat 入口开始，跟踪会话创建失败时 prompt 会发生什么。检查失败期间如何处理 prompt 状态，然后定义一种保留文本并支持重试或复制的恢复行为。完成标准是：会话失败不会丢失已提交的 prompt，用户可以恢复它。

由索引模型根据 Issue 内容生成。