Accounts and credentials
The manager only records each instance's version and sign-in check status — never credentials. You complete Google sign-in yourself in each instance's window; the manager is not involved.
Local files
Pre-upgrade backups are kept in ~/Library/Application Support/Antigravity Multiplexer/Backups/ and are deleted only after you confirm.
Software updates
By default the manager checks the update feed over HTTPS once a day (served by aethernative.com on Cloudflare; earlier versions use GitHub) and downloads installers from GitHub. These services may receive ordinary connection information such as IP address and request headers. Automatic updates can be turned off from the gear menu.