University of Chicago law professor William Baude simply asked Claude to help him change the page numbers in the document.
He went to have lunch. When I came back, I found that the entire year's Constitution class lecture notes and this semester's syllabus were gone.
On November 5, Baude spoke about the incident online and posted screenshots. Claude's reply in the screenshot is to the effect that he mistakenly deleted the 2026 fall semester syllabus and the 2023 class notes in the top-level directory and could not recover them; during the check, he found a page number reference error, but did not change the notebook itself; and then asked him if he could use Dropbox to retrieve it, or if he should try to recover it by itself.
The ending was pretty good, the file had a historical version in Dropbox and was saved.
This type of accident is not new this year, and the process is almost exactly the same: the task is very small (changing page numbers, sorting directories, clearing temporary files), the agent has complete read and write permissions, the person walks away, and when he comes back, there is one more deletion operation that it thinks is reasonable.
A few simple methods are more reliable than expecting the model to make no mistakes:
- The directory that the agent operates must have a version history, either network disk or Git will do.
- For tasks that only change the content, don’t give deletion permission; tools like Claude Code can set the deletion command to confirm every time
- Before leaving the computer, do not leave a task that is running and has write permissions
Lucky for Baude, his files happened to be in Dropbox.