> Maybe there's a way to execute code on commit that would atomicaly
> update the ID field?
>

No there isn't...
Your client starts the transaction and issues a commit. There is no trigger
at the server "onCommit".
I think you're barking up the wrong tree here. You must come to terms with
multi-generational, multi-user and transaction controlled environments in
your model if you are going to make this work for you.

You may need to talk more about your real task at hand - maybe there are
other solutions for what you are trying to do.
Alan