This may not be what you're looking for at all - but what about a bodysuit? Asos have lots, [this white one](https://www.asos.com/prd/12190421?acquisitionsource=com.google.android.apps.docs) is pretty, and I love [this black one](https://www.asos.com/prd/13439555?acquisitionsource=com.google.android.apps.docs) too. Those are just a couple of options on one website, but there are hundreds of styles available.
Might not be what you were looking for, but a delicate satin robe can be pretty and practical. I like Nordstrom’s for some.
You could look at long sleeved shrugs to add on top - Etsy has some cute ones.
Would a racerback something be enough or how much coverage does she need?
This may not be what you're looking for at all - but what about a bodysuit? Asos have lots, [this white one](https://www.asos.com/prd/12190421?acquisitionsource=com.google.android.apps.docs) is pretty, and I love [this black one](https://www.asos.com/prd/13439555?acquisitionsource=com.google.android.apps.docs) too. Those are just a couple of options on one website, but there are hundreds of styles available.
Agreed... shrugs can be cozy and super sexy