Yes! The CLI only updates when you manually run gemshell update. Automatic updates are only available in the window version.
To keep a specific version on your build server, simply install it with npm install -D gemshell@1.2.1. This ensures every build uses the same version. You can also download older CLI versions directly from GitHub.
Pinning GemShell also keeps its Electron version consistent, so the game runtime stays the same.