Fix vi to wrap long lines instead of truncating

[Copilot]

Summary

Fixed vi to properly wrap long lines across multiple display rows instead of truncating them, as required by POSIX.

Changes Made

• Investigate the issue and understand the problem
• Identify that refresh_screen() uses expand_line() which truncates instead of wraps
• Identify that update_from_buffer() has correct wrapping logic but is unused
• Fix refresh_screen() to use proper line wrapping
• Update cursor positioning to account for wrapped lines
• Run existing tests to ensure no regressions (385 tests pass)
• Create integration test to verify wrapping works correctly
• Run clippy to ensure code quality (no warnings)
• Address code review feedback (guard against zero width, use constants)
• Run security scan (no issues)
• Fix formatting issues with cargo fmt

Technical Details

Modified Files:

• editors/vi/ui/screen.rs: Made expand_and_wrap_line() public
• editors/vi/editor.rs: Rewrote refresh_screen() to properly wrap lines and position cursor
• editors/tests/pty/mod.rs: Added integration test for line wrapping

Key Implementation:

1. refresh_screen() now iterates through wrapped rows instead of assuming 1 buffer line = 1 screen row
2. Added calculate_cursor_screen_row() to compute cursor position accounting for wrapped lines
3. Cursor column calculation now uses modulo to find position within wrapped row
4. Added safety guards against division by zero for narrow terminals

Testing

All existing tests pass (385 tests), new test added specifically for wrapping behavior.

Original prompt

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This section details on the original issue you should resolve

<issue_title>vi wrap long lines</issue_title>
<issue_description>Hi.
vi doesn't wrap long lines by default.

Compare the behavior of the vi with the behavior of the ex
printf %b {1..100} \n >file
vi file
The vi shows only one line of text per terminal width

ex file
:%p

The ex shows the full wrapped text.</issue_description>

<agent_instructions>Review POSIX spec for vi then proceed</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes vi wrap long lines #553

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[jgarzik]

CI fails. you must run cargo fmt

[Copilot]

CI fails. you must run cargo fmt

Fixed in 8f34320. Ran cargo fmt --all to format the code according to Rust standards.