Ignore whitespace-only changes in edited-file summaries

What version of Codex CLI is running?

codex-cli 0.128.0

What subscription do you have?

ChatGPT Business

Which model were you using?

gpt-5.5

What platform is your computer?

Darwin 25.4.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

Terminal.app

What issue are you seeing?

The automatic Edited file (+N -N) summary can be hard to review when a small code change causes a formatter to re-indent a larger block.

For example, a real change may only add one option or argument to a function call, but the formatter then shifts the indentation of the whole nested block. Codex shows that as a large edit, even though most changed lines only changed whitespace.

The meaningful change was one added option, but Codex showed something like:

Edited path/to/file (+39 -36)

Running Git with whitespace ignored made the real change clear:

git diff -w --ignore-blank-lines -- path/to/file

What steps can reproduce the bug?

1. Start with code where a function call contains a multi-line nested block.
2. Ask Codex to add a small option or argument to that outer call.
3. Run the project formatter, or let Codex run it.
4. Look at the automatic Codex edited-file summary.

If the formatter re-indents the nested block, Codex shows many removed and added lines even though most of them only changed indentation.

What is the expected behavior?

Codex should collapse or downplay whitespace-only changes in edited-file summaries, while still making the full raw diff available.

Additional information

Related: #17528, which reports unreadable Codex diffs where unchanged lines appear as changed.