Finder Sync not load when the host APP is command line APP

I'm confuse about the loading condition of Finder Sync Extension.

I want to run the Finder sync as a user agent service, so I use a command line tool project and added a Finder sync extension target in the project.

But when I debug the extension in Xcode, select Finder to run, the init method of Finder sync class never called, I also check the Activity Monitor, there is no the Finder sync extension.

But if I use a Cocoa APP, the Finder sync extension will load as normal.

So what's the condition to run a Finder Sync Extension in Finder?