somewhat

I provide job contract and job offer( 13 monthes). I got REF and I was asked to provide new contract(the old one already expired when I got REF). I provided new offer letter(1 year term) with indication of possibility to renew. My case got approved.
I think that you 'd better not provide term contract or job offer unless they require it. The best way is to have letter from your supervisor saying that you will remain in the position for several years.
If you must provide the job offer or contract, you'd better have someting like "with possibility of extention"