/ask and /btw answers go blank while the dialog stays open

Describe the bug

When I use /ask or its /btw alias, answer text appears and then disappears without me pressing Escape or otherwise dismissing the response. The answer box stays open but becomes blank.

This is different from the expected disappearance after explicitly closing the temporary answer panel.

Affected version

1.0.83-5

Steps to reproduce the behavior

1. Run Copilot CLI in the VS Code integrated terminal on Windows.
2. In an existing conversation, submit /ask <a short text-only question> or /btw <a short text-only question>.
3. Allow the answer to render and leave the panel open without dismissing it.
4. Observe that the answer text can disappear while the panel remains open.

This has happened repeatedly in this environment, but a deterministic minimal reproduction has not yet been isolated. It is not established whether a resumed conversation or a concurrently running main task is required.

Expected behavior

Once answer text is displayed, it should remain readable in the open panel until I explicitly dismiss it. Finishing the response should not erase already displayed text.

Additional context

• OS/architecture: Windows, x64.
• Terminal: VS Code integrated terminal.
• Related closed report: github/copilot-cli#3759 describes blank /ask responses on resumed chats in version 1.0.61. Linking as possibly related, not as a confirmed duplicate or regression.

Suspected cause, not confirmed: Completion handling may replace an already streamed answer with an empty value when the final answer payload is empty or missing. A component-level simulation reproduces that failure mode, but the final payload from an actual failing live query has not been captured.

Local workaround status: The symptom was observed before modifying the installation. A temporary local UI workaround was subsequently applied to retain displayed and buffered streamed text when the final answer is empty or missing, while still using a nonempty final answer when provided. Its effectiveness against the original live symptom has not yet been confirmed; it is not an upstream fix or proof of the suspected cause.

首先，在 Windows VS Code 集成终端中复现 /ask 和 /btw；如果可能，还要包括恢复的对话和并发任务。将显示的流式文本和缓冲的流式文本与最终答案 payload 进行比较；当 panel 保持打开时答案仍然可读即表示完成，包括最终 payload 为空或缺失的情况。