that's right, isn't it

I say that it is right.

私は「そうだよね」と言います

I listen to my friend's explanation and say that it is right.

私は友達の説明を聞いて「そうだよね」と言います

I listen to my friend's explanation today and say that it is right.

私は友達の説明を聞いて今日「そうだよね」と言います

I listen to my friend's explanation at the coffee shop today and say that it is right.

私は友達の説明を聞いて今日喫茶店で「そうだよね」と言います

I listen to my friend's explanation at the coffee shop today, nodding, and say that it is right.

私は友達の説明を聞いて今日喫茶店でうなずきながら「そうだよね」と言います