Compact completion box randomly renders replies in a tiny inner scroll area

首先，在 Windows 11 上的 GitHub Copilot desktop app 的 conversation view 中，按照描述使用较长的结构化回复来复现该问题。完成的标准是：回复始终使用正常的、利用可用高度的 conversation layout，不存在很小的嵌套滚动区域或周围未使用的空间。

Short summary

The app sometimes renders a reply inside a compact completion box. That box is only about 1/5 of the vertical window, so the result has to be scrolled inside the tiny box instead of using the full conversation view.

Affected version or release

1.1.20 (github.exe ProductVersion 1.1.20)

Installation context

Windows 11 Enterprise (build 26200), GitHub Copilot desktop app, conversation view.

What happened?

Intermittently, the app shows the model result in a compact completion box: a small nested, scrollable pane that occupies roughly one fifth of the vertical screen.

Instead of reading the answer in the normal full-height transcript, I have to scroll inside that tiny box. The rest of the window stays empty. This makes long answers and structured results hard to read.

It does not happen on every reply. It appears randomly.

Steps to reproduce

1. Open a conversation in the GitHub Copilot desktop app.
2. Ask for a longer structured reply (lists, explanations, multi-part results).
3. Sometimes the reply renders in a compact completion box instead of the normal full-height transcript.
4. Observe that the box is only a small fraction of the window height and has its own scrollbar.

I do not have a reliable repro every time. The compact completion box appears intermittently.

Expected behavior

Replies should use the normal conversation layout and the available window height. If a compact completion box is used, it should not be a tiny inner scroller that is only about 1/5 of the screen.

Additional context

Redacted screenshot of the compact completion box (content scribbled out; this is only to show the cramped inner scroll area):

The inner pane has its own scrollbar. The surrounding conversation view does not expand to use the rest of the vertical space.