REPL cursor in big input 'stops' at top visible line

Version

v25.0.0-pre

Subsystem

repl

What steps will reproduce the bug?

When working with multiline inputs that have more lines than the terminal heights (in lines), moving all to the top of the big input causes the current lower part of the input to be rendered at all times. The cursor effectively moves up, the lower lines just stay the same instead of changing.

This happens when pressing up at the top visible line.

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior? Why is that the expected behavior?

The lines are changed.

What do you see instead?

Wrong cursor movement.

REPL のエントリポイントから開始し、ターミナルよりも高さのある複数行入力で問題を再現してから、最上部の表示行で Up を押します。カーソル移動と表示行の描画がどのように更新されるかを追跡します。カーソルが上に移動するにつれて下の行が正しく変化すれば完了です。