Windows Undo still fails with "patch with only garbage at line 4" even after enabling undo=true

Summary

On Windows, Codex Desktop's Undo/Revert action still fails for a simple one-line edit to an existing tracked text file. The dialog reports:

无法还原更改
Git 应用错误: error: patch with only garbage at line 4

This happens even after explicitly enabling the undo feature in both user and project Codex config files and restarting Codex.

Environment

• OS: Windows
• Shell: PowerShell
• Repo: private Git repository
• Codex app: current Windows desktop build
• Git: core.autocrlf=true from global Git config
• Project has no .gitattributes
• .codex/config.toml contains:

``toml
[features]
undo = true
``

• C:\Users\23233\.codex\config.toml also contains:

``toml
[features]
undo = true
``

Repro steps

1. Open a trusted local Codex thread in a Windows Git repo.
2. Ask Codex to add a single ASCII line to an existing tracked file, for example:

``js
console.log('test-data')
``

1. Confirm the file shows only a one-line diff.
2. Click the Undo/Revert button in the Codex UI.

Actual result

The undo flow fails with:

error: patch with only garbage at line 4

The file remains modified.

Expected result

Codex should revert the single-line change cleanly, or show a concrete actionable conflict state.

Notes

• I first reproduced the issue with a Chinese log line, but then repeated it with pure ASCII to rule out encoding problems.
• The failure persisted after restarting Codex, so this does not appear to be a stale-session-only issue.
• The repository itself is clean except for the one Codex edit.
• This looks related to, but is not identical to, existing reports:
• #28506
• #25048
• #15367

If needed, I can provide a minimal diff, screenshots, and the exact local config values from the machine.