A developer says Codex linked a test project to their real Unity assets, and 4,864 files vanished

This is one person's account on GitHub, not independently confirmed. The developer filed it as a bug report with OpenAI's Codex team on 26 October 2026, and it was still open when we read it.

What happened

The developer was using the Codex desktop app on Windows 11 with a Unity 6 game project. The request was small: improve the animation on a shop purchase-confirmation screen. To check its work, Codex set up a separate, temporary Unity project to test the animation in. Instead of copying the game's assets into that test project, it created an NTFS junction, a Windows link that makes one folder point at another. The test project's Assets folder pointed straight at the real project's Assets folder.

There was a second problem with where it put that test project. It sat inside the real project's Temp directory, a folder Unity owns and treats as disposable.

How it went wrong

Codex then launched Unity against the test project. During the import, Unity reported missing files and failed to write metadata. The temporary junction disappeared, and the real Assets folder was found empty. Git reported 4,864 tracked files deleted, including scripts, prefabs, images and .meta files. Uncommitted changes and new scripts that hadn't been added to git yet were hit too.

The developer is careful about what they claim. The junction and the file loss are backed up by recorded tool calls and what they saw on disk, they say, but the exact process that did the deleting hasn't been established. Several chats and Unity processes were using the same workspace at the time, and another chat was said to be doing cleanup or recovery around then. They didn't ask for anything to be deleted.

Getting it back

All 4,864 tracked files were restored from git. Eleven files with uncommitted work were rebuilt from the agent's own recorded tool calls. Three untracked scripts got new internal IDs because the originals couldn't be recovered, some cache data had to be regenerated, and there was no complete byte-for-byte backup from before the incident. The rebuilt project compiled cleanly.

What they asked for

The report asks Codex to use real copies for verification, keep test projects out of folders that apps clean up, spot junctions and other Windows links before any cleanup, refuse recursive operations that could reach the original source, and coordinate file operations across chats that share a workspace. It links two earlier reports that look related, without claiming the same root cause.

Lesson for builders

This is our opinion. A link is not a copy. On Windows, a junction makes two folders the same folder, so anything that cleans up the 'temporary' side can empty the real one. If your agent builds scratch projects, make it copy files, keep scratch space outside folders other tools wipe, commit before any test run, and don't let several agent chats work on the same folder at once.