How do I open a repository from the terminal?

Install the command line tool from Settings. It creates a symlink at ~/.local/bin/innesta, and tells you if that folder is not on your PATH.

Then:

innesta            # the current directory
innesta .          # the same
innesta ~/Projects/kettle

You can point it at a subfolder — the app finds the repository root.

Running it in a repository that is already open brings that window forward rather than opening a second one.

See the command line tool for exit codes, and for what it deliberately does not do.