With the mortises cut and the legs mostly shaped it was time to glue the chair up again. This included regluing the back, which had some gaps.
I used hide glue for the first time with this project. It was a little thick, I think, which filled the joints and made them a little gappy. Live and learn.
With the frame glued up I could go ahead and cut off the tops of the legs, as the tenons now wouldn't bust out the endgrain. At least not yet!
Then I could shape the recesses to accept the seat.
I decided to reglue the whole thing, as the gappy joints just didn't look right. Succeeded better this time.
I salvaged this piece of 12mm plywood from a dumpster for the base of the seat, and used the pattern pictured in the previous photo to get the shape right.
With a quick coat of wax and the upholstery draped over the seat, this is what it looks like.