During an argument one person capitulates, not because they agree, but just to irritate the other with phrases like:
Yes, of course you are right etc.
Is there a specific word to describe this person?
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The verb that seems to come closest is humor
Comply with the wishes of (someone) in order to keep them content, however unreasonable such wishes might be: she was always humoring him to prevent trouble
This conveys expression of insincere agreement (or conduct) while actually disagreeing. However, the term is often used to describe a process intended to soothe rather than annoy. If irritation is part of the concept ytou wish to convey, you would probably need an adjective
She snidely humored him, agreeing with his every pronouncement, eventually leading to his storming out of the room.
There is a related concept, yes-man
a person who agrees with everything that is said; especially : one who endorses or supports without criticism every opinion or proposal of an associate or superior
Again, there is often an implication that the process is intended to placate rather than annoy. An adjective could change that
He was a transparent yes-man. His boss found the unbridled enthusiasm annoying, not flattering.