We believe that freely undertaken works of love are necessary for our finlal justification, but we also know that these works have that effect solely because of the sacrifice of Christ. "Works-based salvation" would imply that we earn our salvation independently of Christ through overall acts of righteousness. This might be what some (pelagian) Christians believe, but it is not the Catholic belief.
But our justification has been finalized. Our justification is complete because it is an act of Christ and not of us. Jesus Christ gave Himself up on the cross and rose from the dead. We have been justified completely and forever by His sacrifice.
I realize this puts certain churches at a loss because then they can't dole out salvation according to their own dictates. But Scripture is clear that all who believe in Jesus Christ have been justified by His atonement, once for all time.
[we]"...are justified freely by his grace through the redemption that came by Christ Jesus. God presented him as a sacrifice of atonement, through faith in his blood... He did it to demonstrate his justice at the present time, so as to be just and the one who justifies those who have faith in Jesus." -- Romans 3:25,26 "He was delivered over to death for our sins and was raised to life for our justification." -- Romans 4:25 "...through Jesus the forgiveness of sins is proclaimed to you. Through him everyone who believes is justified from everything you could not be justified from by the law of Moses." -- Acts 13:38 "those he predestined, he also called; those he called, he also justified; those he justified, he also glorified." -- Romans 8:30"Therefore being justified by faith, we have peace with God through our Lord Jesus Christ" -- Romans 3;20,28
And as a preemptive thank-you, my "Scripture generator" is working just fine. However, it's more aptly called "Open Bible; Read It." 8~)
In any context such as this, the word "based" does not at all imply exclusivity. It implies a main part or a foundation. Since you said the work of Christ was done (I agree here), and that salvation is not yet had by the believer, then the sine qua non of salvation can only remain in the works of men. Do you agree? Therefore, from the man's POV, his salvation, as he experiences it, is based on his works.
I see the Catholic view being that Christ's work made all this possible. IOW, in Catholicism, Christ didn't actually accomplish salvation for any person in particular for all time. Instead, He, by His sacrifice, made it POSSIBLE for men to choose to do their works, and THEN be saved for all time. I still think that with an explanation, that is a fair description of a "works-based" salvation.
Please note that I am not calling you a Nestorian or an Arian or anything like that. Sometimes, things just "sound" bad and need an explanation. LOL! :)