I would compare your prototype with the sellitem-jsf sample, and also review the JSF section of Chapter 5 in the reference manual, along with the "sellitem-jsf" walkthrough in the Practical documentation chapter. You'll read in this literature you are not required to track the _flowExecutionKey parameter--it's tracked for you.
Since you are using SWF with JSF, I would also recommend upgrading to the latest nightly 1.0.4 snapshot. These snapshots are complete and stable--we're simply waiting a bit on releasing 1.0.4 to make sure the remaining known JSF integration issues (mostly issues that occur in exceptional scenarios) are taken care of.
Nightly builds are here: http://static.springframework.org/do...hp?project=SWF
Core Spring Development Team