simonwillison.net·Jul 16, 2026
Simon Willison's weblog discusses a reported bug in GPT-5.6 that led to unexpected file deletions, primarily occurring when full access mode is enabled without proper sandboxing protections. The issue arises when the model mistakenly overrides the $HOME environment variable, resulting in the deletion of critical files.
The key takeaway for you is the identified bug in GPT-5.6 where file deletions occur due to a lack of sandboxing protections when using Codex in full access mode. To prevent this, ensure sandboxing and auto-review are enabled, especially if assigning tasks to AI like Claude, Cursor, or Copilot through Jira or similar platforms.