Fix display of wrapped lines at file end

[hgwr]

Summary

• ensure window scrolls to show full line when moving to last line
• add regression test for wrapped last line visibility

Testing

• cargo build --verbose
• cargo test --verbose
• pip install -r e2e/requirements.txt
• pytest -n auto e2e --verbose

---

https://chatgpt.com/codex/tasks/task_e_6896f01032fc832f8558a1c7653b997a

[gemini-code-assist]

Summary of Changes

Hello @hgwr, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

I've addressed an issue where wrapped lines, particularly at the end of a file, might not be fully visible when navigating to them. My changes ensure that the terminal window automatically scrolls to accommodate the entire line, providing a better user experience. This includes a core logic update and a new test to confirm the fix.

Highlights

• Enhanced Scrolling for Wrapped Lines: I've implemented a fix in the NextLine command's execution logic to ensure that when the cursor moves to a new line, especially a wrapped one, the entire line is visible on the screen. This is achieved by dynamically adjusting the window's scroll position if the line would otherwise extend beyond the bottom of the terminal.
• New Regression Test for Visibility: To prevent regressions and validate the new scrolling behavior, I've added a new end-to-end test, test_last_line_wrapped_visible. This test specifically verifies that a long line at the end of a file, which wraps across multiple display rows, is fully shown when the cursor navigates to it.

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[gemini-code-assist]

Code Review

This pull request fixes an issue where a long, wrapped line at the end of a file might not be fully visible after navigating to it. The change modifies the NextLine command to ensure the window scrolls sufficiently to display the entire wrapped line. A new end-to-end test is also added to verify this behavior and prevent regressions.

The implementation in src/command/commands/move_cursor.rs correctly adjusts the window position. I have one minor suggestion to improve code quality by removing an unnecessary mutable variable declaration. The new test case in e2e/test_wrapping.py is well-written and covers the scenario effectively. Overall, this is a good fix.

[gemini-code-assist]

The variable next_line_height is declared as mutable but is never reassigned. The mut keyword can be removed to avoid a compiler warning and improve code clarity.

Suggested change

	let mut next_line_height =
	get_line_height(next_line, editor.terminal_size.width) as u16;
	let next_line_height =
	get_line_height(next_line, editor.terminal_size.width) as u16;