What about if Peer-A splice the first element (0) which results in ['b'] and Peer-B wants to mutate 'a' to 'A' which results in ['A','b'] and they both make the mutation at the same millisecond?
Now rather than not knowing what magic is going to happen, app developers know what to expect in advance.
So atomic would choose one or the other, not a combined result.
Fixed array 2nd item to 1st which nulls 2nd and makes 1st b, simultaneously also makes 1st A. Cause lower case b is lexically larger than A, you'd get [b, null].
Linked list theoretically could handle it as you suggest.
