An AI coding agent built on Anthropic’s Claude Fable model deleted approximately 700 GB of data from an independent developer’s home directory while executing a script meant to clean up temporary sandbox files. A variable collision caused the agent to run its destructive delete against the wrong directory, and an automatic safety-triggered downgrade to Opus 4.8 mid-task may have contributed to the error. The developer recovered roughly 90% of the lost work from an older backup drive and from GitHub, with the remainder unrecoverable.