This is, without a doubt, a work in progress. I've been learning React as I go, and there are still sizeable gaps in my understanding.
What you have here is a server that saves to the user's session (in-process only -- better to spend time on a persistent solution, n'est-ce pas?). There is no client-side code that exercises the save yet. I have, however, got some test coverage for the storage model.
The client side demonstrates some of the presentation semantics, both read-write and read-only, but no real
CRUD with the server yet. Also, I could well have done with fetch(), but jQuery was handy, so I went with
it. No tests yet, I've been trying to get basic happy-path functionality going.
I will continue on this as time permits.