Please report security problems privately, not in a public issue: use Report a vulnerability on the repository's Security tab. Say what you found, how to reproduce it, and which version of Lucid and macOS you used. Lucid is maintained by one person: expect a reply as soon as possible, and a fix or a plan after that.

• Lucid has no account, no server and no analytics. Your pages are files in ~/Lucid (or LUCID_HOME).
• The language model is reached at a local address (127.0.0.1 by default); Settings refuses an address that is not on your computer.
• The only network use of Lucid's own code is the one-time download of typesetting files by its PDF engine (Tectonic), and the web pages you open from the Help menu.
• AI agents reach the app through a socket in the library folder (~/Lucid/.lucid/lucid.sock) that only your user can use on macOS and Linux, and through a named pipe on Windows (named after the library folder, with the usual Windows protection for a pipe: other users cannot write to it). An agent can only edit a page it has just read, and every change is one undo step, listed in the history.
• The window loads only the app's own files, under a content security policy.
• Lucid is not notarized by Apple and not signed for Windows. Check the SHA-256 of a download against SHA256SUMS in the release.

Only the latest release gets fixes.