We have liftoff!
The babies have all left the nest (they were hanging with Mama in a nearby tree). I managed to get pictures of the last one to go before it joined its siblings, but our front porch is quiet again now, and I am not getting berated by Mama Robin every time I need to water the plants.
(Note: we did have a little adventure with the last one to go – after I took that top picture, it jumped out of its nest without full ability to fly, though it was pretty close. Choppy decided a robin snack might be a good idea when she saw it, but I saved it before Choppy could have her way. I replaced it in the nest, where you can see the baby stayed before joining everyone else.)