view tool rejects a normal 8.6 KB file as too large to read at once

Describe the bug

The built-in view tool (shown as Read in the VS Code UI) reports File too large to read at once (8.6 KB) when asked to read a small, ordinary multiline Markdown file. This appears to be a false-positive size warning and makes normal full-file inspection unnecessarily cumbersome.

This is not the large single-line JSON or custom-tool-output case. The file is a regular Markdown document and is approximately 8.6 KB.

Affected version

Unknown - encountered in the Copilot CLI runtime integrated with VS Code.

Steps to reproduce the behavior

1. Use the Copilot CLI runtime in VS Code on Windows.
2. Ask the agent to read a normal multiline Markdown file of approximately 8.6 KB.
3. Allow the built-in view/Read tool to read the file without specifying a range.
4. Observe the File too large to read at once (8.6 KB) warning instead of the file contents.

Expected behavior

A normal file of this size should be read successfully in full. If a size threshold is required, the threshold should be consistent, documented, and should not report ordinary small files as too large without a clear reason.

Additional context

• OS: Windows 11
• Host: Visual Studio Code
• Tool: built-in view/Read
• File type: regular Markdown, approximately 8.6 KB
• The warning recommends using view_range, even though the file is small enough that a full read would normally be expected.
• This report is about the view tool's full-file size handling, not Azure DevOps or the repository being inspected.

找出內建的 view/Read 實作和完整檔案大小檢查，然後在所述的 Windows 和 VS Code 設定中，使用一個約 8.6 KB 的多行 Markdown 檔案重現問題。追查這個正常檔案為何會被拒絕；完成的標準是檔案能完整讀取且不會出現誤報警告，同時真正過大的輸入或單行輸入仍得到適當處理。