Meta Muse launched in the US on mobile and web in early September, and reached the Mac about ten days later. The desktop app is what puts it in this directory: it acts inside native macOS applications rather than only answering questions. Access to the machine is opt-in, full disk access is optional, and Meta says steps like deleting files or sending messages ask for approval first.
One thing we could not settle, and it is not a small one. The reporting conflicts on where the work actually happens: some accounts describe Muse driving applications on your Mac, others say it runs in cloud virtual machines. Those are different products from a security standpoint — one holds your files, the other holds a copy — and the entry says so rather than picking the more flattering reading.
A researcher also reported that a locally running process could change an undocumented Muse configuration setting. We found no response from Meta.