General Chat is silently archived after session resume timeout, with no restore UI

Summary

A long-running General Chat was silently archived when the app failed to resume it within 60 seconds. I did not archive or delete the chat. The app automatically created a replacement chat, while the original disappeared from the sidebar with no UI to view or restore archived chats.

Environment

• GitHub Copilot app: 1.1.8 (0945da4)
• Bundled Copilot CLI: 1.0.79-9
• OS: Windows x86_64

Observed behavior

1. Opened an existing General Chat with substantial history.
2. The UI appeared unresponsive for about a minute.
3. The original chat disappeared and a newly created chat became active.
4. The original chat was absent from the session list.
5. Attempting to navigate to its ID returned: This chat is archived. Restore it before continuing.
6. There is no archived-chat list or Restore action in the app UI.

The local database showed that the original general_chat row received an archived_at value at exactly the same time the replacement session was created. Clearing only that archived_at value restored the original chat and its full history, confirming the data had not been deleted.

Relevant sanitized log timeline

09:36:25 resuming session ... session_type=GeneralChat
09:37:25 session resume timed out; releasing CLI and surfacing error ... timeout_secs=60
09:37:26 Failed to resume session ... the CLI process may be unresponsive, attempting to recreate
09:37:26 Recreating session old_session_id=<original>
09:37:33 CLI session created cli_session_id=<replacement>
09:37:33 SessionManager create_session flow completed session_id=<replacement>

The original row's archived_at timestamp was 09:37:33.779, immediately after the replacement session was created.

Expected behavior

• A resume timeout must not silently archive an existing chat.
• If a replacement process/session is needed, the existing chat identity and history should remain visible and recoverable.
• The app should surface the timeout and offer Retry rather than replacing the chat without consent.
• If chats can be archived, the UI must provide an Archived view and Restore action.

Impact

This looks like data loss to the user and strands important long-running chat history. Recovery currently requires manually editing the app's SQLite database, which is not a safe or reasonable user workflow.

まず60秒のresumeタイムアウトを再現し、ローカルSQLite行のarchived_atの変更と併せてSessionManager create_sessionのフローを調査します。元のチャットが引き続き表示され、復元可能であること、タイムアウトのフィードバックにRetryが提示されること、アーカイブ済みのチャットにビューとRestoreアクションがあることを確認します。