Arrow keys at top/bottom of prompt field cause current prompt to be lost

When editing a long prompt in the input field, pressing the up or down arrow keys while the cursor is at the top or bottom of the field causes the entire current prompt to be replaced (likely by command history navigation). This has caused loss of carefully formatted long prompts multiple times.

Expected behavior: Arrow keys at the boundaries of the text field should either stop at the boundary or only navigate history when the field is empty/cursor is on the first or last line.

Actual behavior: The current prompt content is completely lost and replaced by a previous command from history.