Does anyone know of a CA case law that speaks to this?
Why do you think case authority is needed or would be of any benefit whatsoever?
Can't intelligently say more than that without knowing what your (hopefully written) settlement agreement says about what happens in the event of default by the other party.
One option is to file a motion for a default judgment for the amount you originally sued for plus your costs.
Send him a copy. If he doesn't respond you get your default judgment and then your judgement can become a lien on his house. You can garnish wages and levy bank accounts. Execute against non-exempts assets.
A couple problems with this. First, we don't know whether seeking a default judgment is appropriate. The OP told us that the other party didn't pay as agreed, but that doesn't tell us anything about whether the other party has been served or whether a responsive pleading is yet due or whether a responsive pleading has been filed. Second, it's not at all clear what the nature of the lawsuit is. It sounds to me like the OP is a tenant who sued his/her landlord, but we don't know what the basis of the suit is.
I think that one main issue at this point is if he is still obligated to be out by 10/31?
Concur. The OP made it clear that his/her obligation to dismiss the lawsuit is contingent on payment being made, but it's not clear whether the failure to pay also negates the obligation to move out.