The great thing about dressing gowns and bath robes is that they sew up fast. In theory I could still insert piping, but sewing together the main body seams gets me this! And I don’t think I need it!
The next step is sew and baste on the lapels and cuffs. To attach them, I need the lining. Linings are not very interesting, but they can save a lot of work. For instance, in this garment I don’t have to wrestle with finishing the inside seams, because they will be invisible, hidden by the lining. To ensure that the garment hangs evenly I will hem the outer and the inner fabrics separately, and then tack them together at the seams. The skirt, which I may well wear hanging open, will be lined in red (because I happen to have a quantity of red taffeta lining) and I could piece it together at the back and through the upper body and sleeves with black. I bought two yards of black fabric for this, plenty.
But the key duty of the lining is to back up the lapels, so that I can attach them. I am using the lining to face the lapels because the dark spriggy fabric is already pretty stiff and heavy. Doubling face fabric is traditional but then they would be very heavy, possibly too much. Also, turning those scallops will be a lot easier if the backing is lighter. I want a neat sharp turn for each of those indentations, which will call for trimming and skill.