codex - 💡(How to fix) Fix Codex Diff fail to pin down the exact lines that are changed [1 participants]

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openai/codex#17528Fetched 2026-04-12 13:27:00
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Code Example

...
- line a unchanged
- line b unchanged
- line c unchanged
- line d old
- line e unchanged
+ line a unchanged
+ line b unchanged
+ line c unchanged
+ line d new
+ line e unchanged
...

---

...
line a
line b
line c
- line d old
+ line d new
line e
...
RAW_BUFFERClick to expand / collapse

What version of the IDE extension are you using?

26.409.20454

What subscription do you have?

Plus

Which IDE are you using?

VS Code

What platform is your computer?

Microsoft Windows NT 10.0.26200.0 x64

What issue are you seeing?

When codex is used to make some modifications, the Codex Diff is all messed up. Some lines are "changed" into the exact same line, causing the diff to be practically unreadable. Example:

...
- line a unchanged
- line b unchanged
- line c unchanged
- line d old
- line e unchanged
+ line a unchanged
+ line b unchanged
+ line c unchanged
+ line d new
+ line e unchanged
...

What steps can reproduce the bug?

Just make codex edit some files and take a look at the codex diff.

What is the expected behavior?

Only the actual modified lines should appear in the diff view. Running Example

...
line a
line b
line c
- line d old
+ line d new
line e
...

Additional information

No response

extent analysis

TL;DR

The issue with the Codex Diff displaying unchanged lines as modified may be resolved by adjusting the diff generation algorithm or configuration to ignore identical lines.

Guidance

  • Review the Codex Diff generation logic to ensure it correctly identifies and filters out unchanged lines.
  • Verify that the diff view is properly configured to display only modified lines, and check for any settings or options that may be causing the issue.
  • Test the Codex Diff with a minimal example to isolate the problem and determine if it's related to specific file types, sizes, or editing operations.
  • Consider reporting the issue to the IDE extension developers or seeking assistance from their support team, as it may be a bug or limitation in the current version.

Notes

The provided information suggests a potential issue with the diff generation algorithm or configuration, but without further details about the Codex Diff implementation or the specific editing operations being performed, it's difficult to provide a more targeted solution.

Recommendation

Apply workaround: The best course of action would be to report the issue and wait for a fix or apply a temporary workaround, such as manually reviewing the diff output to filter out unchanged lines, as upgrading to a fixed version is not currently an option.

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