William Baude, a professor at the University of Chicago Law School, asked the AI assistant Claude to update the page numbers on an older version of his constitutional law lecture notes. After stepping out for a meal, he came back to discover that Claude had not only failed to complete the task but had accidentally deleted an entire year's worth of class notes along with this semester's course syllabus. Claude proactively notified him of the error but took no corrective action—it merely asked whether to restore the files from cloud storage or whether any further steps were needed. AI agents granted direct local file operation permissions in this manner are highly susceptible to accidentally deleting or overwriting important data once they make a misjudgment or when permissions are improperly configured. In the end, the professor restored all the accidentally deleted key files via cloud storage and publicly shared this experience, urging the public to stay vigilant about AI's local file operation permissions and to back up important data.