In a settlement agreement silent as to costs and attorney fees, plaintiffs promised to dismiss their action, with prejudice, on substantial performance of defendants' promise to establish four transit systems. Our central question is whether that agreement operates as a merger and bar of all preexisting claims, depriving the trial court of jurisdiction to award costs and statutory attorney fees. (Code Civ. Proc., ยงยง 1032, 1021.5)*fn1